Chapter V: Foreword (4)

_U.S.A._--Four live and 14 dead specimens from 4 aircraft, Miami (Welch, 1939). One live and 15 dead specimens (adults?) from 16 aircraft; 8 oöthecae from 7 planes; 147 live and 83 dead nymphs from 108 planes, Miami (Denning et al., 1947). Southern U.S. (Hughes, 1949). Five live and 7 dead specimens, Miami (Porter, personal communication, 1958).

IV. CLASSIFICATION OF THE ASSOCIATIONS

Asano (1937) classified the natural enemies of cockroaches into two types as follows:

1. Enemies that feed mainly on cockroaches (certain ripiphorid
beetles and certain chalcid, evaniid, and ampulicid wasps).

2. Organisms which, in their search for food, devour cockroaches
that may be encountered (certain species of scorpions, spiders,
ticks, centipedes, Strepsiptera, ants, birds, rats, and
"parasitic bacteria").

Cameron (1955) arranged the associates of cockroaches in two groups as follows:

Group A. Parasites and predators.

1. Parasites: Hymenoptera (Evaniidae, Eulophidae, Eupelmidae,
Encyrtidae, Pteromalidae, Cleonymidae) and Coleoptera
(Ripiphoridae).

2. Predators: Hymenoptera (Ampulicidae), Hemiptera (Reduviidae),
Coleoptera (Dermestidae), Arachnida (Araneae, Acarina).

Group B. Parasites and symbionts.

1. Protozoa (including examples of both parasites and
commensals).

2. Nematoda (including both primary "parasites" and secondary
parasites).

3. Bacteria (including the mutualistic bacteroids).

4. Algae [_Arthromitis_ (= _Hygrocrocis_) _intestinalis_; see p.
124].

Asano's arrangement, although essentially true, is limited; Cameron's system is divided into arthropods (group A) and lower forms (group B), but does not include higher animals. Both attempts at classification need amplification; this we have endeavored to do below.

In classifying the biotic associates of cockroaches, we were immediately confronted with a problem in semantics. The concepts parasitism, predatism, and symbiosis have all been used with various shades of meaning by different authors. The problem is not solved merely by accepting as authoritative specific definitions, however apt they seem to be, because, unfortunately, these concepts are not mutually exclusive. For example, among the entomophagous insects, as Sweetman (1936) has pointed out, there can be no definite line of separation between parasitism and predatism: the two intergrade, only the extremes being quite distinct. In fact, Andrewartha and Birch (1954) generalized these relationships by calling both categories predatism. These authors divided natural populations of associated organisms into nonpredators and predators. Although this simplifies their presentation of the general principles of ecology, for our purpose more narrowly defined terms have proved useful.

In the main we have followed Sweetman (1936) and Allee et al. (1949) in arriving at the following definitions:

=Symbiosis= is the living together in more or less intimate association of organisms of different species; it includes virtually all relationships between cockroaches and other organisms, such as parasitism, predatism, commensalism, and mutualism. Allee et al. (1949) apparently do not include predatism in symbiosis.

=Mutualism= is symbiosis in which both members benefit by the association. The smaller partner has commonly been called a symbiont or symbiote by authors.

=Commensalism= includes associations in which neither party appears to benefit or be harmed. One partner may live on the surplus food or wastes of the other; shelter and transport may be involved.

=Parasitism= is the state of symbiosis in which one of the members feeds upon the other during the whole of either the immature or mature feeding stage; the host is harmed in some way and may be killed.

=Predatism= is an association in which one member attacks and feeds upon, or stores as food for its progeny, one or more other organisms; the predator spends less than the immature or mature feeding period on the prey. This category includes a few invertebrates and all the vertebrates that capture, kill, and feed on cockroaches. This association may be divided into interspecies predatism, in which the predator preys upon a different species, and intraspecies predatism (cannibalism) in which the predator preys upon its own species.

Although we have attempted to adhere to these definitions throughout this discussion, we realize that in doing so we may have tended to oversimplify complex relations. Some questionable interpretations stem from insufficient knowledge of the basic relationships between cockroaches and their associates. Only further study will clarify these relationships. Some of the problems are discussed below.

Probably many of the so-called parasites (e.g., Protozoa like _Nyctotherus_, and intestinal nematodes of the family Thelastomatidae), which do not invade the host's tissues and seem to have no effect on the activity and vitality of the host, are commensals. Although we consider these forms to be commensals, we realize that they might actually affect the host in some way even though this has not been shown. It is possible that Rothschild and Clay's (1957) statement about bird parasites may well apply to the apparently harmless organisms found in the cockroach. These authors wrote, "It cannot be too strongly emphasized that the effect of all types of parasites on the host is detrimental. If we find that a bird seems little, if at all, inconvenienced by the presence of Protozoa or worms or lice, or a cuckoo in the nest, we can nevertheless assume that it would be better off without them.... Small effects such as lack of vitality, loss of voice, excessive blinking, or perverted habits like dirt eating are extremely difficult to gauge. Nevertheless, it is only a question of degree. Potentially all parasites are harmful." It should also be pointed out that some workers would consider certain of our commensals of cockroaches to be parasites. Thus Faust (1955) stated that "A truly successful parasite is one which has developed a state of equilibrium with its host, so that no detectable damage is produced which endangers the health or life of the host. In a suitable host the parasite may obtain food and shelter without any evidence of trauma or toxicity. The damage produced may be so slight that repair and functional readjustment keep pace with the injury." Faust's successful parasite would be indistinguishable from a commensal, but there is undeniably a difference between an organism causing slight, and undetectable, damage to a host and one causing none. Certain of the organisms we list as commensals may eventually be shown to be parasites.

Certain organisms which live in cockroaches appear to have no effect on the vitality of the host even though the tissues of the host are invaded. Gregarines may penetrate the intestinal wall of the cockroach without seeming to injure the host. Fungi of the genus _Herpomyces_ invade the cuticle of cockroaches producing pathological changes; yet the insects' behavior is apparently unaffected (see p. 129). We consider these organisms to be parasites because the host's tissues are invaded and, as far as we know, no benefit to the host results.

In the literature certain insects have been considered to be either parasites or predators or both. Among these are the ensign wasps (Evaniidae), whose larvae feed on the eggs of cockroaches within the oötheca, and the ampulicid wasps, which capture, paralyze, and store in their nests (as food for their larvae) nymphs and adults of cockroaches. Clausen (1940) claimed that the evaniid _Zeuxevania splendidula_ is a true egg parasite when it destroys the first egg in a cockroach oötheca; but after the wasp larva molts and proceeds to devour the other eggs, he considered it to be a predator. Clausen's definition of an entomophagous parasite is an insect that in its larval stage develops either internally or externally upon a _single_ host which is eventually killed; with few exceptions the adults are free-living and their food is usually different from that of the larvae. A predatory insect, by Clausen's definition, is principally free-living in the larval as well as adult stage, kills the host immediately by direct attack, and requires a number of victims to reach maturity; the predator is of greater size than the prey, and the food sources of the adults and immature stages are frequently the same.

It is apparent, as Clausen and other writers have pointed out, that there are instances of a particular species showing characteristics which fit both the definitions for predator and parasite. Thus, among the evaniids one wasp larva destroys all the eggs in an oötheca, but in spite of this the larva has more of the characteristics of a parasite than of a predator; the adult wasp does not utilize the same food as the larva (adults have been taken on flowers and on honeydew from scale insects). It is questionable whether the evaniid larva kills the cockroach egg outright. The wasp larva, being restricted to the inside of the oötheca, is not free-living. Probably the only criterion by which the evaniid could be judged to be a predator, by Clausen's definition, is that more than a single egg is devoured by the maturing wasp larva.

Among the other wasp parasites (Encyrtidae, Eulophidae, Eupelmidae) of cockroach eggs many individuals develop in a single oötheca. When a hundred or more wasps emerge from an oötheca which contained less than 20 eggs, it is obvious that a single cockroach egg supported more than one wasp, yet it is possible that one particular wasp larva may have fed upon more than one cockroach egg before becoming an adult. We consider all entomophagous wasps that develop in cockroach oöthecae to be parasites rather than predators.

On the other hand, even though _Anastatus floridanus_, _A. tenuipes_, and _Tetrastichus hagenowii_ are egg parasites as larvae, the adult females are, in a sense, predators when they sometimes eat part of the cockroach egg that oozes through the oviposition puncture (Roth and Willis, 1954a, 1954b). Williams (1929) has seen the female of _Ampulex canaliculata_ imbibe blood that oozed from the cut ends of the cockroach's antennae after she had clipped them off before leading the prey to her nest. Yet despite this evident predatism on the part of the adult, the larva feeds as a parasite on the stored cockroaches in accordance with Sweetman's (1936) (though not Clausen's 1940) definition of parasitism, which is "that form of symbiosis in which one symbiont lives in or on the host organism and feeds at its expense during the whole of either the immature or mature feeding stage." The ampulicid larva, as the evaniid, is not free-living and does not kill the host immediately by direct attack, even though it may require more than one victim to reach maturity. Thus, within one individual both parasitic and predatory behavior are operant during different stages of its life history.

With the above discussion in mind we have summarized below the various biotic associations of cockroaches. Only a few examples are given for each section, but all organisms with similar habits presumably would be classified in the same categories.

Class A. Associations in which cockroaches serve as hosts, vectors,
or prey for other organisms.

Type I. Obligate associates. Animals and plants that normally
develop only on or in the cockroach; in general, these
organisms depend entirely upon the cockroach for survival.

Group 1. Mutuals (symbiotes or symbionts of authors).

(a) Bacteria-like organisms (bacteroids which are found in the
fat body of all cockroaches that have been examined; p. 96).

(b) Bacteria (wood-digesting forms in _Panesthia_, and possibly
certain bacteria in the intestines, of other cockroaches;
p. 100).

(c) Protozoa (several genera and species found in
_Cryptocercus_; p. 101).

Group 2. Commensals.

(a) Protozoa (_Nyctotherus_, _Herpetomonas_, _Lophomonas_, etc.;
p. 172).

(b) Nematodes (Thelastomatidae; p. 193).

Group 3. Parasites.

(a) Fungi (Laboulbeniales; p. 134).

(b) Protozoa (gregarines, _Plistophora_, etc.; p. 181).

(c) Helminths.

(1) Primary parasites (mermithids and gordian worms;
p. 201).

(2) Secondary parasites (_Gongylonema neoplasticum_,
_Oxyuris mansoni_, _Moniliformis_ spp.; p. 206).

(d) Arthropods.

(1) Mites (_Pimeliaphilus podapolipophagus_; p. 219).

(2) Insects (larvae of ripiphorids, evaniids, and
ampulicids; p. 231).

Type II. Facultative associates. Animals and plants that prey on
cockroaches or are incidentally or accidentally picked up by the
cockroach, but which can survive or propagate readily on some
other host or prey. Steinhaus (1946) emphasized the importance of
the environment in determining the type of microbial flora
associated with the cockroach which may carry one type of flora
in an area which is exposed to filth and a different type in
other areas. Because many of these organisms survive passage
through or on the cockroach, the blattid may act as a vector of
these animals and plants.

Group 1. Commensals.

(a) Viruses (strains of poliomyelitis virus; p. 103).

(b) Bacteria (Enterobacteriaceae, Pseudomonadaceae,
Micrococcaceae, etc.; p. 111).

(c) Fungi (_Aspergillus_; p. 130).

(d) Protozoa (_Iodamoeba_, _Dobellina_, and cysts of
_Entamoeba coli_ and _Entamoeba histolytica_; p. 179).

(e) Helminths (cysts of various helminths parasitic in
vertebrates; p. 208).

(f) Arthropods.

(1) Mites (_Tyrophagus lintneri_; p. 218).

Group 2. Parasites.

(a) Bacteria (_Serratia marcescens_; p. 117).

(b) Helminths (_Protospirura_ spp.; p. 206).

(c) Arthropods.

(1) Mites (_Locustacarus_ sp.; p. 219).

(2) Insects (_Melittobia chalybii_; p. 248).

Group 3. Predators, active.

(a) Arthropods.

(1) Spiders (p. 214).

(2) Scorpions (p. 212).

(3) Centipedes (p. 222).

(4) Mites (_Rhizoglyphus tarsalus_; p. 218).

(5) Insects (dermestids, reduviids, and on occasion adult
females of _Tetrastichus_, _Anastatus_, _Ampulex_;
p. 234).

(b) Vertebrates.

(1) Amphibia (p. 269).

(2) Reptilia (p. 272).

(3) Aves (p. 276).

(4) Mammalia (p. 283).

Group 4. Predators, passive: Pitcher plants (p. 154).

Class B. Associations in which cockroaches serve as commensals or
predators.

Group 1. Commensal cockroaches.

(a) Associates of social insects (_Attaphila_ spp., etc.;
p. 315).

(b) Obscure associates (p. 316).

Group 2. Predatory cockroaches.

(a) Interspecies predators (p. 319).

(b) Intraspecies predators (p. 322).

Class C. Associations of cockroaches with other cockroaches.

Group 1. Intraspecies associations.

(a) Familial associations (p. 325).

(b) Other conspecific associations (aggregations and fighting)
(p. 336).

Group 2. Interspecies associations.

(a) Compatible associations (p. 337).

(b) Antagonistic associations (p. 329).

Class D. Ecological associations of cockroaches with higher
plants.

Group 1. Benign associations (p. 139).

Group 2. Associations detrimental to plants (p. 162).

V. MUTUALISM

BACTEROIDS

Blochmann (1887, 1888) discovered intracellular particles (the bacteroids or symbiotes of authors) that resembled bacteria in the fat body of males and females of _Blatta orientalis_ and _Blattella germanica_ (pl. 26), in the ova of these insects, and in their embryos. Bacteroids have since been found in at least 25 species and 19 genera of cockroaches. Presumably such microorganisms are universally distributed throughout the Blattaria. General reviews of the bacteroids of cockroaches and other insects have been published by Glaser (1930b), Schwartz (1935), Steinhaus (1946, 1949), Buchner (1952, 1953), Brooks (1954), and Richards and Brooks (1958). The reader is referred to these papers, and those of authors cited in the list at the end of this section, for discussions of the morphology of the bacteroids, their distribution within the host, and attempts to culture them in vitro.

It has long been assumed, without proof, that cockroaches and their bacteroids form a mutually beneficial association. As it has not been possible to cultivate bacteroids apart from their cockroach hosts, it may be assumed that the host is essential to the continued existence of the microorganism, which also derives from the association other obvious benefits as well. Experiments to show that the host also benefits from the association have centered around rendering cockroaches bacteroid free. Starvation, parasites, electromagnetic radiation, heat or cold, or chemicals have all been used in attempts to eliminate the bacteroids. Of these, only chemical treatment has provided a satisfactory technique.

Few chemicals other than antibiotics have proved to be useful in the elimination or reduction of bacteroids. Yetwin (1932) injected various dilutions of 22 compounds into _Blattella germanica_. He observed decreases in the bacteroids of the fat body only following injection of methylene blue, but did not pursue this lead further. Gier (_in_ Steinhaus, 1946) observed reduction in the numbers of bacteroids after cockroaches were injected with crystal violet, hexylresorcinol, or metaphen. Bode (1936) reported that injection of irritants such as lithium salts or quinine hydrochloride had no apparent effect on the symbiotes.

Brooks (1957) reared _Blattella germanica_ on diets containing different concentrations of inorganic ions. On a manganese-deficient diet the cockroaches grew poorly and some of their progeny lacked normal bacteroids; about 10 percent of the aposymbiotic generation grew and reproduced on a diet fortified with yeast. Varying the concentrations of other salts in the diets gave results in which the progeny were either aposymbiotic or the fat body was abnormal but the mycetocytes were abundant; all these cockroaches soon died even on fortified diets.

The administration of certain antibiotic drugs has produced cockroaches very nearly free of bacteroids. Brues and Dunn (1945) found that although sulfa drugs had no effect on the bacteroids, penicillin in large doses reduced the number of bacteroids in _Blaberus craniifer_, but the cockroaches died within a few days. Death was attributed to lack of bacteroids rather than effect of the drug; this is perhaps an unwarranted conclusion in view of the survival of aposymbiotic cockroaches that have been produced by other drugs (Brooks, 1954; Brooks and Richards, 1955). Glaser (1946) found that the bacteroids of _Periplaneta americana_ could be adversely affected or destroyed by sulfathiazole, or sodium or calcium penicillin. Fraenkel (1952) questioned the conclusions of Brues and Dunn (1945) and of Glaser (1946) because of the high mortality in their experiments, and he suggested that the described phenomena "were due rather to direct toxic effects on the host than to loss of the symbionts." Noland (_in_ Brooks, 1954; Brooks and Richards, 1955) confirmed Glaser's results with penicillin and extended sulfa treatments to include _Blattella germanica_. Every female whose bacteroids were reduced to the vanishing point resorbed her ovaries and was incapable of reproduction. Brooks (1954; Brooks and Richards, 1955) found that administration of several antibiotics did not eliminate the bacteroids from the fat body of _B. germanica_ unless the dose was so high that it caused excessive mortality. Frank (1955, 1956) was able to eliminate bacteroids from _Blatta orientalis_ by injecting or feeding chlortetracycline, oxytetracycline, or penicillin; survival of treated insects was not good and reproduction was poor; the aposymbiotic individuals were smaller than normal. As Richards and Brooks (1958) have pointed out, it is uncertain how much of this difference was the result of loss of bacteroids and how much the effect of the drug. It is obvious that in all these experiments the action of the drugs on the bacteroids was accompanied by equivocal side effects which confused interpretation of the results. The effect on the cockroach of a loss of bacteroids cannot be separated from a possible toxic effect of the drug.

Fortunately Brooks (1954; Brooks and Richards, 1955) obtained completely aposymbiotic offspring from _Blattella germanica_ that had been reared on aureomycin. These bacteroid-free nymphs were practically incapable of growth on a natural diet that was adequate for nymphs with symbiotes. However, the addition of large amounts of dried yeast to the diet enabled aposymbiotic nymphs to mature in two to three times the period required by normal nymphs. Final proof of the function of the bacteroids was obtained by reestablishing them in aposymbiotic cockroaches. The insects that received implants of normal fat body of _B. germanica_ showed a slow, steady gain in weight over the controls (Brooks, 1954; Brooks and Richards, 1956). Obviously, the intracellular symbiotes subserve the normal nutrition of the cockroach. Whether the bacteroids produce only vitaminlike substances, as suggested by Keller (1950), or function in some other way is still to be determined. Brooks (1954) concluded that the amount of vitamin-containing food required for increased growth by aposymbiotic cockroaches is much greater than the known vitamin requirements; hence the factor(s) needed is unknown and present in low concentration, or it serves as a precursor of a second factor(s) whose synthesis is aided by the bacteroids. Brooks (_in_ Richards and Brooks, 1958) has since found that the bacteroids of _Blattella germanica_ "can supply the insect with B vitamins, amino acids and some larger protein fragment."

Gier (1947) stated that the symbiotes of cockroaches are generically all the same. However, as the symbiotes are presumed to have been associated with cockroaches for over 300,000,000 years (Buchner, 1952) they may be assumed to have developed specific differences that link them inseparably to their respective hosts. Ries (1932) transplanted symbiote-containing fat body from _Blatta orientalis_ into the mealworm and larva of _Ephestia kühniella_, and from _Blattella germanica_ and _Stegobium paniceum_ (=_Sitodrepa panicea_) into _B. orientalis_. The implants did not become established in the new host, although most of the transplantations were successful in that the hosts survived and the implants remained intact for some time before they were encapsulated by host tissue. Brooks (1954; Brooks and Richards, 1956) transplanted fat body of _Periplaneta americana_ and _B. orientalis_ into aposymbiotic _B. germanica_. The growth of the cockroaches injected with foreign tissue was not different from that of aposymbiotic controls. Sections of host insects did not contain mycetocytes and no bacteroids were found. Haller (1955a) injected bacteroids or implanted mycetocytes of _B. germanica_ into gryllids, acridids, and locustids. These implants and innoculations were rapidly destroyed by the hosts. But as Richards and Brooks (1958) have pointed out, none of these experiments provide information about the specificity of the bacteroids themselves.

COCKROACHES IN WHICH BACTEROIDS HAVE BEEN FOUND

_Bantua stigmosa._ Fraenkel (1921)

_Blaberus craniifer._ Brooks (1954); Brues and Dunn (1945); Hoover
(1945).

_Blaberus giganteus._ Blochmann (1892).

_Blatta orientalis._ Blochmann (1887, 1888, 1892); Bode (1936);
Brooks (1954); Buchner (1912); Cuénot (1896); Fraenkel (1921);
Frank (1955, 1956); Gier (1936, 1947); Glaser (1920);
Gropengiesser (1925); Gubler (1948); Heymons (1895); Hollande
and Favre (1931); Hoover (1945); Hovasse (1930); Javelly (1914);
Keller (1950); Koch (1949); Menel (1907)?; Mercier (1906a, 1907,
1907b, 1907c); Ries (1932); Ronzoni (1949); Tacchini (1946); Wolf
(1924, 1924a).

_Blattella germanica._ Blochmann (1887, 1888, 1892); Bode (1936);
Borghese (1946, 1948, 1948a); Brooks (1954); Brooks and Richards
(1954, 1955, 1955a, 1956); Fraenkel (1921); Gier (1936, 1947);
Glaser (1920, 1930a); Gropengiesser (1925); Haller (1955, 1955a);
Heymons (1892, 1895); Hoover (1945); Koch (1949); Lwoff (1923);
Milovidov (1928); Neukomm (1927, 1927a, 1932); Pérez Silva (1954,
1954a); Ries (1932); Rizki (1954); Ronzoni (1949); Tacchini
(1946); Wollman (1926); Yetwin (1932, 1953).

_Cryptocercus punctulatus._ Gier (1936, 1947); Hoover (1945).

_Derocalymma cruralis._ Fraenkel (1921).

_Ectobius lapponicus._ Heymons (1892); Cuénot (1896); Koch (1949).

_Ectobius pallidus._ Heymons (1892, 1895); Cuénot (1896).

_Epilampra grisea._ Fraenkel (1921).

_Eurycotis floridana._ Gier (1936, 1947).

_Loboptera decipiens._ Buchner (1930).

_Nauphoeta cinerea._ Fraenkel (1921).

_Nyctibora noctivaga._ Gier (1947).

_Parcoblatta lata._ Gier (1936, 1947).

_Parcoblatta pensylvanica._ Brooks (1954); Gier (1936, 1947).

_Parcoblatta uhleriana._ Gier (1936, 1947); Hoover (1945).

_Parcoblatta virginica._ Glaser (1920); Gier (1947).

_Periplaneta americana._ Baudisch (1956); Bode (1936); Cuénot
(1896); Gier (1936, 1937, 1947); Glaser (1920, 1930, 1946);
Gubler (1948); Hertig (1921); Hoover (1945); Ketchel and
Williams (1953).

_Periplaneta australasiae._ Gier (1936, 1947); Koch (1949).

_Platyzosteria armata._ Fraenkel (1921).

_Polyphaga aegyptiaca._ Fraenkel (1921).

_Pseudoderopeltis aethiopica._ Fraenkel (1921).

_Pycnoscelus surinamensis._ Bode (1936); Koch (1949).

_Supella supellectilium._ Brooks (1954).

BACTERIA

Evidence showing that intestinal bacteria contribute to the nutrition of cockroaches is meager. Cleveland et al. (1934) isolated a bacterial organism from the foregut of the wood-feeding cockroach _Panesthia angustipennis_. The bacterium digested cellulose rapidly in vitro and these workers believe that this cockroach and other related wood-feeding species are dependent on symbiotic bacteria for the digestion of their food.

Mencl (1907) described cell nuclei in "symbiotic," not closely defined types of bacilli that he found in abundance in the digestive tract of the Küchenschabe, _Periplaneta_ (presumably _Blatta orientalis_). Unfortunately, he was more concerned about the morphology of the bacteria than the stated mutualistic relationship, so nothing is known of their physiology.

The growth rates of _Periplaneta americana_ and _Blattella germanica_ were retarded when the insects were reared aseptically, which suggests that microorganisms normally found in the digestive tract supply certain necessary dietary constituents (Gier, 1947a; House, 1949). Noland et al. (1949) suggested that microorganisms in the digestive tract of _B. germanica_ synthesized riboflavin since the nymphs reared on a low riboflavin diet accumulated more of the vitamin than could have been ingested in the diet. However, Metcalf and Patton (1942) found little or no bacterial synthesis of riboflavin in _P. americana_. Noland and Baumann (1951) suggested that methionine, one of the amino acids essential for rapid growth of _B. germanica_, was synthesized by intestinal microorganisms in the insects.

PROTOZOA

It is probable that with few exceptions protozoa found in the digestive tract are not necessary for survival of the cockroach. However, very few experiments have been performed to determine the importance, if any, of these microorganisms to the host. Cleveland (1925) removed the protozoa from the cockroach (possibly _Periplaneta americana_) by oxygenation at 3.5 atmospheres. The ciliates _Nyctotherus_ and _Balantidium_, flagellates _Lophomonas_ and _Polymastix_, the amoeba _Endamoeba blattae_, and three unidentified protozoa were killed by this treatment, yet the insects lived normally after defaunation.

Armer (1944) studied the effects of high-carbohydrate, high-fat, and high-protein diets, as well as starvation, on the intestinal protozoa (_Nyctotherus ovalis_, _Endamoeba blattae_, _Endolimax blattae_, _Lophomonas striata_, and _Lophomonas blattarum_) in _Periplaneta americana_. Starvation of the host lowered the incidence or eliminated most of the protozoa, but a high-carbohydrate diet maintained them at a relatively high level. _Lophomonas blattarum_ was eliminated by a high-protein diet, and practically eliminated by a high-fat diet. _Lophomonas striata_ was eliminated from some hosts that were kept on high-fat and high-protein diets. _Endamoeba blattae_ showed a decrease in infection rate when the cockroaches were maintained on high-fat and high-protein diets. The effects of diets on _Endolimax blattae_ were not uniform.

It has been shown by Cleveland (1930, 1948) and Cleveland et al. (1931, 1934) that the wood-feeding cockroach _Cryptocercus punctulatus_ depends upon certain intestinal protozoa for survival; these protozoa utilize as food the wood ingested by this cockroach. The wood is broken down into compounds the cockroach can utilize by the protozoa which elaborate a cellulase and possibly a cellobiase (Trager, 1932). Only molting nymphs of _Cryptocercus_ can pass the protozoa on to the newly hatched young, so that molting and hatching must happen concurrently each year or the young die.

The sexual cycles in species of protozoa in the genera _Trichonympha_, _Saccinobaculus_, _Oxymonas_, _Monocercomonoides_, _Hexamita_, _Eucomonympha_, _Leptospironympha_, _Urinympha_, _Rhynchonympha_, _Macrospironympha_, and _Barbulanympha_ (fig. 3, B) are induced by hormones produced by _Cryptocercus_ only during its molting period (Cleveland, 1931, 1947, 1947a, 1949-1956a). Perhaps the prothoracic gland hormone of the host may be responsible for initiation of the flagellate sexual cycles (Cleveland and Nutting, 1955). The protozoan sexual cycles may be used as indicators of the onset of molting in _Cryptocercus_; thus different species of protozoa begin their sexual cycles from 35 days before to 2 days after molting of the cockroach (Cleveland and Nutting, 1954). Hollande (1952) and Grassé (1952) have reviewed the roles and the evolution of the flagellates in _Cryptocercus_ and in termites.

The protozoa of cockroaches and termites are clues to the relationship between these two groups of insects. Kirby (1927) pointed out similarities between _Endamoeba blattae_ of _Periplaneta_ and the amoebae of the termite _Mirotermes_, suggesting that these protozoans were probably derived from an amoeba in an ancestor common to both blattid and termite. Kirby (1932, _in_ Kidder, 1937) found a species of _Nyctotherus_ in _Amitermes_ that resembles _Nyctotherus ovalis_ from domestic cockroaches. The belief that the termites and cockroaches had a common origin is also strengthened by the similarities between the hypermastigotes of both _Cryptocercus_ and termites (Cleveland et al., 1934).

The cockroaches _Cryptocercus_ and _Panesthia_ both feed on wood, but the protozoa found in _Panesthia_ resemble more closely the species in domestic cockroaches than those in _Cryptocercus_. The Clevelandellidae (from _Panesthia_) are closely related to _Nyctotherus_ and have probably evolved from common ancestors. However, the separation of the Clevelandellidae from _Nyctotherus_ must have taken place at a later date than the divergence of their hosts, otherwise representatives of that family would probably also be found in _Periplaneta_ and _Blatta_ (Kidder, 1937).

The protozoa of _Cryptocercus_ can be transferred from one individual to another (Nutting and Cleveland, 1954). They can also be transferred to the termite _Zootermopsis_ where they survive only until the host molts; the reverse is also true, _Zootermopsis_ Protozoa can survive in _Cryptocercus_ until the cockroach molts (Nutting and Cleveland, 1954a).

VI. VIRUSES ASSOCIATED WITH COCKROACHES

Annotations on some of the following observations may be found in Roth and Willis (1957a). Use of asterisk is explained in footnote 3, page 4.

POLIOMYELITIS VIRUSES

* =Lansing strain=

_Experimental vectors._--_Blattella germanica_, U.S.A. (Hurlbutt, 1949, 1950).

_Periplaneta americana_, U.S.A. (Hsiang et al., 1952).

* =Brunhilde type, Minnesota and Mahoney strains=

_Experimental vectors._--_Periplaneta americana_, U.S.A. (Fischer and Syverton, 1951; Syverton et al., 1952).

* =Columbia SK virus=

_Experimental vectors._--_Periplaneta americana_, Great Britain? (Findlay and Howard, 1951): Results with _Blattella germanica_ were negative.

* =Four unspecified strains=

_Natural vectors._--_Blattella germanica_ and/or _Blattella vaga_, _Periplaneta americana_ and/or _Periplaneta brunnea_, and _Supella supellectilium_, U.S.A. (Syverton et al., 1952; Dow, 1955; Dow _in_ Roth and Willis, 1957a).

OTHER VIRUSES

* =Coxsackie viruses=

_Experimental vectors._--_Periplaneta americana_, U.S.A. (Fischer and Syverton, 1951a, 1957): Recently Fischer and Syverton (1957) found that after feeding a single meal of Coxsackie virus to _Periplaneta americana_, the gastrointestinal tracts of the insects, which were removed at 5-day intervals up to 20 days, contained sufficient virus to paralyze and kill test mice. Cockroach salivary glands, removed 5 days after the insects had fed, contained the virus which caused paralysis and death in test mice; mice were also infected by virus obtained from salivary glands removed from the insects 10 and 20 days after the cockroaches had fed once on the virus. The virus was also isolated from the cockroaches' feces and rarely from the fat bodies and reproductive organs. Fischer and Syverton concluded that it is possible that cockroaches could acquire the virus, by feeding on mammalian excreta, maintain it for a period of time, and transmit it by contamination of food. The virus could also be transmitted through the feces of wild mice if the mice happened to feed on virus-infected cockroaches.

* =Mouse encephalomyelitis virus=

_Experimental vectors._--_Periplaneta americana_, U.S.A. (Syverton and Fischer, 1950).

* =Yellow-fever virus=

_Experimental vectors._--_Blattella germanica_, Great Britain? (Findlay and MacCallum, 1939).

VII. BACTERIA ASSOCIATED WITH COCKROACHES

Classification of the bacteria follows Breed et al. (1948). Synonymy in most cases was taken from the same source. Names of bacteria preceded by the symbol [cross] are either not listed by Breed et al. or are stated by them to be insufficiently characterized for definite classification. Use of asterisk is explained in footnote 3, page 4.

Phylum SCHIZOPHYTA

Class SCHIZOMYCETES

Order EUBACTERIALES

Family PSEUDOMONADACEAE

* =Pseudomonas aeruginosa= (Schroeter) Migula

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, U.S.A. (Olson and Rueger, 1950).

_Blattella germanica_, U.S.A. (Olson and Rueger, 1950; Janssen and Wedberg, 1952).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a; Olson and Rueger, 1950).

_Experimental vectors._--_Blattella germanica_, U.S.A. (Herms and Nelson, 1913).

Cockroaches, U.S.A. (Longfellow, 1913).

* =Pseudomonas eisenbergii= Migula

_Natural and experimental vectors._--_Blatta orientalis_, Italy (Cao, 1906).

* =Pseudomonas fluorescens= Migula

_Natural and experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898, 1906; Spinelli and Reitano, 1932).

_Periplaneta americana_, U.S.A. (Gier, 1947): The organism was pathogenic to the cockroach when injected.

[cross] =Spirillum periplaneticum= Kunstler and Gineste

_Habitat._--_Periplaneta americana_, France? (Kunstler and Gineste, 1906): From intestinal tract.

[cross] =Spirillum α, β, and γ= Dobell

_Habitat._--_Blatta orientalis_, England (Dobell, 1911, 1912): From hind gut.

=Spirillum= sp.

_Habitat._--_Blatta orientalis_, U.S.S.R. (Zasukhin, 1930): From intestinal tract.

Cockroaches, Venezuela (Tejera, 1926): From digestive tract.

* =Vibrio comma= (Schroeter) Winslow et al.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898; Spinelli and Reitano, 1932).

_Blattella germanica_, Orient (Toda, 1923); Germany (Jettmar, 1927).

_Periplaneta americana_, Philippine Islands (Barber, 1914); Netherlands (Akkerman, 1933); Formosa (Morischita and Tsuchimochi, 1926).

_Periplaneta australasiae_, Formosa (Morischita and Tsuchimochi, 1926).

* =Vibrio metschnikovii= Gamaléia

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898, 1906).

=Vibrio tyrogenus= (Flügge) Holland

_Synonymy._--_Vibrio_ of Deneke.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898): The organism passed through the intestinal tract unchanged.

[cross] =Vibrio Types I and II= Heiberg

_Habitat._--Water.

_Natural vectors._--Cockroaches, India (Pasricha et al., 1938): The vibrios were found in 16 or 17 percent of 94 cockroaches and resembled _Vibrio comma_ in their morphology and their main biochemical reactions; however, serum-agglutination reactions differed.

=Vibrio= sp.

_Habitat._--_Blatta orientalis_, U.S.A. (Leidy, 1853): From intestine.

Family RHIZOBIACEAE

=Chromobacterium violaceum= (Schroeter) Bergonzini

_Synonymy._--_B. violaceus._

_Habitat._--Water.

_Experimental vectors._--Cockroach, U.S.A. (Longfellow, 1913): Recovered from outer part of body and intestinal tract.

Family MICROCOCCACEAE

* =Micrococcus aurantiacus= (Schroeter) Cohn

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952).

* =Micrococcus citreus= Migula

_Natural vectors._--Cockroaches, U.S.A. (Longfellow, 1913).

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

* =Micrococcus epidermidis= (Winslow and Winslow) Hucker

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952).

[cross] =Micrococcus nigrofaciens= Northrup

_Source._--Diseased June beetle larvae.

_Experimental infection._--_Periplaneta americana_, U.S.A. (Northrup, 1914): Three of four adults were infected by feeding them bread saturated with a broth culture of the _Micrococcus_. After 11 days the tarsi of the cockroaches became infected, and the hind legs split and broke off. Antennae and setae also were affected and micrococci were recovered from the feces.

* =Micrococcus pyogenes= var. =albus= (Rosenbach) Schroeter

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, U.S.A. (Tauber, 1940; Tauber and Griffiths, 1942).

_Blattella germanica_, U.S.A. (Herms and Nelson, 1913; Herms, 1939; Janssen and Wedberg, 1952).

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898); U.S.A. (Tauber and Griffiths, 1942).

_Micrococcus pyogenes_ var. _albus_ (=_Staphylococcus albus_) and an unidentified short rod form were found by Tauber (1940) in the hemolymph of _B. orientalis_. These microorganisms were never found together in the same insect and caused loss of appetite, sluggishness, irregular respiratory movements, and paralysis in the cockroach; in the final stages of the disease the legs were folded under the body, the head was tucked beneath the forelegs, the whole insect became arched and maintained this position until death. In some cockroaches infected with the rod pathogen, conjunctival folds, particularly those between the dorsal abdominal sclerites, and the joints of the metathoracic legs ruptured liberating thick white hemolymph filled with bacteria. Tauber suggested that the infection might be spread by contact, especially to newly molted individuals or by actual ingestion of the bacteria by the cockroaches feeding on dead or dying individuals. All the roaches died after successful inoculation with the _Micrococcus_. The bacterial infection was associated with high total hemocyte counts and high percentages of mitotically dividing hemolymph cells (Tauber, 1940); these responses of the insect were interpreted as a mechanism whereby the number of hemocytes increases resulting in an increase in the number of phagocytes for combating the bacteria (Tauber and Griffiths, 1942).

* =Micrococcus pyogenes= var. =aureus= (Rosenbach) Zopf

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, Italy (Cao, 1906).

_Blattella germanica_, U.S.A. (Herms, 1939).

Cockroaches, U.S.A. (Longfellow, 1913).

=Micrococcus ureae= Cohn

_Habitat._--Stale urine and soil containing urine.

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952): From intestinal tract and feces.

* =Micrococcus= spp.

These organisms were obtained from pus or were designated as staphylococci [i.e., pathogenic micrococci (Blair _in_ Dubos, 1948)].

_Natural vectors._--_Blatta orientalis_, Italy (Spinelli and Reitano, 1932); Germany (Jettmar, 1935).

_Blattella germanica_, Germany (Jettmar, 1935).

_Experimental vectors._--_Blattella germanica_, on shipboard (Morrell, 1911); Germany (Vollbrechtshausen, 1953).

=Micrococcus= sp.

_Natural vectors._--_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948): From intestinal tract.

[cross] =Sarcina alba= Zimmermann

_Habitat._--Water.

_Natural and experimental vectors._--_Blatta orientalis_, Italy (Cao 1898, 1906): From intestinal contents.

=Sarcina aurantiaca= Flügge

_Habitat._--Air and water.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1906): Intestinal contents.

=Sarcina lutea= Schroeter

_Habitat._--Air, soil, water, skin surfaces.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1906): From intestinal contents.

[cross] =Sarcina symbiotica= Pribram

_Habitat._--Oöthecae of _Blatta orientalis_ and/or _Blattella germanica_, Germany (Gropengiesser, 1925): It was described as "eine gelbe _Sarcina_"; Pribram (1933) named the organism.

=Sarcina ventriculi= Goodsir

_Habitat._--Garden soil, dust, mud; isolated from a diseased stomach.

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): From intestinal tract.

=Sarcina= sp.

_Natural and experimental vectors._--_Periplaneta americana_, U.S.A. (Gier, 1947): Organism not pathogenic to the cockroach when injected.

[cross] =Sarcina= sp.

_Synonymy._--_Sarcina_ "blanche" of Sartory and Clerc.

_Natural vectors._--_Blatta orientalis_, France (Sartory and Clerc, 1908): Isolated from intestinal tract.

*[cross] =Sarcina= sp.

_Synonymy._--_Sarcina alba_ "patogena" of Cao.

_Natural vectors._--_Blatta orientalis_, Italy (Cao, 1898, 1906).

*[cross] =Sarcina= sp.

_Synonymy._--_Sarcina_ "bianca" and "gialla" of Cao.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

Family NEISSERIACEAE

* =Neisseria meningitidis= (Albrecht and Ghon) Holland

_Experimental vectors._--Cockroaches, U.S.A. (Longfellow, 1913).

* =Veillonella parvula= (Veillon and Zuber) Prévot

_Natural vectors._--_Periplaneta americana_, U.S.A. (Hatcher, 1939).

Family LACTOBACTERIACEAE

* =Diplococcus pneumoniae= Weichselbaum

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

Cockroaches, U.S.A. (Longfellow, 1913).

[cross] =Enterococcus= sp.

_Natural vectors._--_Blatta orientalis_, Italy (Spinelli and Reitano, 1932): From intestinal tract.

=Lactobacillus fermenti= Beijerinck

_Habitat._--Fermenting plant or animal products.

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): From intestinal canal.

[cross] =Pneumococcus Type I, No. 1231=

_Experimental vectors._--_Blattella germanica_, Germany (Vollbrechtshausen, 1953).

* =Streptococcus faecalis= Andrewes and Horder

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946).

_Blattella germanica_, U.S.A. (Steinhaus, 1941).

_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948).

Cockroaches [presumably any or all of the above three species], Egypt (El-Kholy and Gohar, 1945).

* =Streptococcus liquefaciens= Sternberg emend. Orla-Jensen

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946).

*[cross] =Streptococcus microapoika= Cooper, Keller, and Johnson

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946).

*[cross] =Streptococcus non-hemolyticus II= Holman

_Natural vectors._--_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948).

* =Streptococcus pyogenes= Rosenbach

_Natural vectors._--_Blatta orientalis_, Italy (Cao, 1906).

_Experimental vectors._--Cockroaches, U.S.A. (Longfellow, 1913).

* =Streptococcus= sp. (pyogenic group)

_Experimental vectors._--_Blatta orientalis_, Germany (Jettmar, 1935).

* =Streptococcus= sp. (_viridans_ group)

_Experimental vectors._--_Blatta orientalis_, Germany (Jettmar, 1935).

* =Streptococcus= spp.

_Natural vectors._--_Blatta orientalis_, Germany (Jettmar, 1935).

_Blattella germanica_, Germany (Jettmar, 1935); U.S.A. (Janssen and Wedberg, 1952).

Cockroaches, U.S.A. (Longfellow, 1913).

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

Family CORYNEBACTERIACEAE

* =Corynebacterium diphtheriae= (Flügge) Lehmann and Neumann

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

Cockroaches, U.S.A. (Longfellow, 1913).

Family ACHROMOBACTERIACEAE

[cross] =Achromobacter hyalinum= (Jordan) Bergey et al.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Hatcher, 1939): Isolated from feces.

=Achromobacter= sp.

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952).

=Alcaligenes faecalis= Castellani and Chalmers

_Synonymy._--_Bacillus faecalis alkaligenes_; _Bacillus alcaligenes faecalis_; _B. alcaligenes faecalis_.

_Habitat._--Intestinal canal of man. Has been isolated from feces, abscesses related to intestinal canal, and occasionally in the bloodstream. However, it is generally considered nonpathogenic.

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): Isolated from feces.

_Blatta orientalis_, Poland (Nicewicz et al., 1946): Isolated from intestinal tract.

_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952): From intestinal tract and feces.

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): Isolated from intestinal tract.

Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_ and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945): From suspensions of macerated whole insects.

=Alcaligenes recti= (Ford) Bergey et al.

_Synonymy._--_B. alcaligenes recti._

_Habitat._--Intestinal canal.

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): Isolated from intestinal tract.

=Alcaligenes viscosus= (Weldin and Levine) Weldin

_Habitat._--Water, dairy utensils; produces ropiness in milk.

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952): Isolated from intestine and feces.

Family ENTEROBACTERIACEAE

=Aerobacter aerogenes= (Kruse) Beijerinck

_Synonymy._--_Bacillus lactis aerogenes._

_Habitat._--Grains, plants, intestinal tract of man and other animals.

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): Isolated from feces.

_Blatta orientalis_, Poland (Nicewicz et al., 1946): Isolated from intestinal tract.

_Blattella germanica_, on shipboard (Morrell, 1911): Isolated from feces.

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): Isolated from intestinal tract.

Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_ and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945): Isolated from outer surface of body, intestinal tract, and suspensions of macerated whole insects.

=Aerobacter cloacae= (Jordan) Bergey et al.

_Synonymy._--_Bacillus cloacae._

_Habitat._--Sewage, soil, water, human and other animal feces.

_Natural vectors._--_Blattella germanica_, on shipboard (Morrell, 1911): From feces. U.S.A. (Janssen and Wedberg, 1952; Steinhaus, 1941): From intestinal tract, feces, and oötheca.

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): From intestinal tract.

=Aerobacter= sp.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): Isolated from intestines.

[cross] =Eberthella oedematiens= Assis

_Habitat._--Intestinal canal.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): Intestinal tract.

* =Escherichia coli= (Migula) Castellani and Chalmers

_Natural vectors._--_Blatta orientalis_, Italy (Cao 1898, 1906; Spinelli and Reitano, 1932); France (Sartory and Clerc, 1908); Europe (Jettmar, 1935); Poland (Nicewicz et al., 1946).

_Blattella germanica_, U.S.A. (Steinhaus, 1941).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

Cockroaches [presumably one or all of the above three species], Egypt (El-Kholy and Gohar, 1945).

Cockroaches, U.S.A. (Longfellow, 1913).

_Experimental vectors._--_Blattella germanica_, Germany (Vollbrechtshausen, 1953): When injected anally or orally the bacteria invaded the intestinal cells and in heavy infections killed the cockroaches.

=Escherichia coli= var. =acidilactici= (Topley and Wilson) Yale

_Synonymy._--_Bacillus acidi lactici._

_Source._--Diseased nun moth larvae.

_Experimental vectors._--_Blatta orientalis_, Europe (Filatoff, 1904): Organism pathogenic to cockroach when injected but not when fed.

=Escherichia coli= var. =communior= (Topley and Wilson) Yale

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): From feces.

=Escherichia freundii= (Braak) Yale

_Habitat._--Soil, water, intestinal canal of man and other animals.

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): From feces.

_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952): From intestinal canal and feces.

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): From intestinal tract.

=Escherichia intermedium= (Werkman and Gillen) Vaughn and Levine

_Habitat._--Soil, water, intestinal canal of man and other animals.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949): From intestinal canal.

* =Klebsiella pneumoniae= (Schroeter) Trevisan

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

* =Paracolobactrum aerogenoides= Borman, Stuart and Wheeler

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949).

* =Paracolobactrum coliforme= Borman, Stuart and Wheeler

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949).

* =Paracolobactrum= spp.

_Natural vectors._--_Blatta orientalis_, U.S.A. (Olson and Rueger, 1950).

_Blattella germanica_, U.S.A. (Olson and Rueger, 1950).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949; Olson and Rueger, 1950).

* =Paracolon bacilli=

_Natural vectors._--Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_ and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945).

* =Proteus mirabilis= Hauser

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

* =Proteus morganii= (Winslow et al.) Rauss

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_, and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945).

* =Proteus rettgeri= (Hadley et al.) Rustigian and Stuart

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949).

* =Proteus vulgaris= Hauser

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, Italy (Spinelli and Reitano, 1932).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

Cockroaches, U.S.A. (Longfellow, 1913).

* =Proteus= spp.

_Natural vectors._--_Blatta orientalis_, U.S.A. (Olson and Rueger, 1950).

_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949; Olson and Rueger, 1950).

* =Salmonella anatis= (Rettger and Scoville) Bergey et al.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella choleraesuis= (Smith) Weldin

_Experimental vectors._--_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Salmonella enteritidis= (Gaertner) Castellani and Chalmers

_Experimental vectors._--_Blatta orientalis_, U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Blattella germanica_, U.S.A. (Olson and Rueger, 1950); U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Salmonella morbificans= (Migula) Haupt

_Natural vectors._--_Periplaneta americana_, Australia (Mackerras and Mackerras, 1948, 1949).

_Experimental vectors._--_Nauphoeta cinerea_, _Periplaneta australasiae_, _Periplaneta ignota_, and _Supella supellectilium_, Australia (Mackerras and Pope, 1948).

* =Salmonella paratyphi= (Kayser) Castellani and Chalmers

_Experimental vectors._--_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Salmonella schottmuelleri= (Winslow et al.) Bergey et al.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

_Experimental vectors._--_Periplaneta americana_, Gold Coast Colony (Macfie, 1922).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Salmonella= sp. (=Type Adelaidae=)

_Experimental vectors._--_Nauphoeta cinerea_, _Periplaneta australasiae_, _Periplaneta ignota_, and _Supella supellectilium_, Australia (Mackerras and Pope, 1948).

* =Salmonella= sp. (=Type Bareilly=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Bredeny=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

* =Salmonella= sp. (=Type Derby=)

_Experimental vectors._--_Nauphoeta cinerea_, _Periplaneta australasiae_, and _Supella supellectilium_, Australia (Mackerras and Pope, 1948).

* =Salmonella= sp. (=Type Kentucky=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Kottbus=)

_Experimental vectors._--_Periplaneta australasiae_, Australia (Mackerras and Pope, 1948).

* =Salmonella= sp. (=Type Meleagris=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Montevideo=)

_Experimental vectors._--_Periplaneta americana_, U.S.A. (Jung and Shaffer, 1952).

* =Salmonella= sp. (=Type Newport=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Oranienburg=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a; Eads et al., 1954).

_Experimental vectors._--_Blatta orientalis_, _Blattella germanica_, and _Periplaneta americana_, U.S.A. (Olson and Rueger, 1950).

* =Salmonella= sp. (=Type Panama=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Rubislaw=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella= sp. (=Type Tennessee=)

_Natural vectors._--_Periplaneta americana_, U.S.A. (Eads et al., 1954).

* =Salmonella typhimurium= (Loeffler) Castellani and Chalmers

_Natural vectors._--_Blattella germanica_, Belgium (Graffar and Mertens, 1950).

_Nauphoeta cinerea_, Australia (Mackerras and Mackerras, 1948).

_Experimental vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Blattella germanica_, Belgium (Graffar and Mertens, 1950); U.S.A. (Olson and Rueger, 1950; Janssen and Wedberg, 1952; Beck and Coffee, 1943); U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Nauphoeta cinerea_, Australia (Mackerras and Pope, 1948).

_Periplaneta americana_, U.S.A. (Beck and Coffee, 1943; Jung and Shaffer, 1952).

_Periplaneta australasiae_ and _Supella supellectilium_, Australia (Mackerras and Pope, 1948).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Salmonella typhosa= (Zopf) White

_Natural vectors._--_Blatta orientalis_, Italy (Antonelli, 1930, 1943).

_Experimental vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, Italy (Spinelli and Reitano, 1932); U.S.A. (McBurney and Davis, 1930); U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952); Germany (Jettmar, 1927); U.S.S.R. (Rozengolts and Ȋȗdina _in_ Pavlovskii, 1948).

_Periplaneta americana_, Gold Coast Colony (Macfie, 1922); Netherlands (Akkerman, 1933); Formosa (Morischita and Tsuchimochi, 1926); U.S.A. (Olson _in_ Roth and Willis, 1957a).

_Periplaneta australasiae_, Formosa (Morischita and Tsuchimochi, 1926).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_, and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945).

=Serratia marcescens= Bizio

_Synonymy._--_Bacillus prodigiosus_, _Bacterium prodigiosum_.

_Habitat._--Water, soil, milk, foods, and various insects.

_Natural hosts._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): From intestinal tract. Italy (Spinelli and Reitano, 1932).

_Blattella germanica_, Canada (Heimpel and West, 1959).

_Diploptera punctata_, _Nauphoeta cinerea_, _Neostylopyga rhombifolia_, _Panchlora nivea_, _Pycnoscelus surinamensis_, and _Supella supellectilium_, U.S.A. (Roth and Willis, unpublished data, 1958): The organism was isolated and identified by Dr. Hillel Levinson, Quartermaster bacteriologist, from dead specimens found in our laboratory colonies which showed the red coloration characteristic of insects that have died with infections of _S. marcescens_ (pl. 16, A, B).

_Leucophaea maderae_, U.S.A. (Levinson, personal communication, 1958): The organism was isolated from the hemolymph of living insects while attempting to determine the cause of unexplained mortality in our laboratory colony of this insect.

_Leucophaea maderae_ or _Periplaneta americana_, Philippine Islands (Barber, 1912): From hemolymph.

_Periplaneta americana_, U.S.A. (Gier, 1947; Steinhaus, 1959).

_Periplaneta australasiae_ and _Periplaneta brunnea_ (Roth and Willis, unpublished data [1954]): In laboratory colonies. Isolated from suspensions of ground insects. In 1954 we received a culture of _Periplaneta brunnea_ from the Department of Public Health, University of Minnesota. These insects began to die off rapidly and the normally lightly pigmented parts of the body became red. Dr. Hillel Levinson, Quartermaster bacteriologist, cultured _Serratia marcescens_ from several moribund individuals. The Department of Public Health of Minnesota had at times in the past cultured _S. marcescens_ but had discarded the cultures and was unaware that it might be surviving in the cockroach colonies (Richards, personal communication, 1954).

_Periplaneta_ sp., U.S.A. (Olson _in_ Roth and Willis, 1957a): Isolated from an undetermined species of _Periplaneta_, received in a shipment from the South, a strain of _S. marcescens_ which was toxic to mice when administered intraperitoneally.

_Experimental hosts._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): When fed in small numbers, _S. marcescens_ increased to such an extent that the insect's extremities and upper halves of their bodies turned deep red. The insects died after this color appeared and practically pure cultures of _Serratia_ were recovered from the reddened areas.

_Blatta orientalis_, Italy (Cao, 1898): Isolated from intestinal contents. Passed unchanged through the gut.

_Blattella germanica_, Canada (Heimpel and West, 1959): Not normally pathogenic per os; LD_{50} by injection, is approximately 38,000 bacteria per insect.

_Periplaneta americana_, U.S.A. (Gier, 1947): Organism toxic to the cockroach when injected.

Cockroaches, U.S.A. (Longfellow, 1913): Isolated from legs and viscera after feeding experiments.

* =Shigella alkalescens= (Andrewes) Weldin

_Natural vectors._--_Periplaneta americana_, U.S.A. (Bitter and Williams, 1949, 1949a).

* =Shigella dysenteriae= (Shiga) Castellani and Chalmers

_Experimental vectors._--_Blatta orientalis_, Italy (Spinelli and Reitano, 1932).

_Periplaneta americana_, Formosa (Morischita and Tsuchimochi, 1926).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

* =Shigella paradysenteriae= (Collins) Weldin

_Natural vectors._--_Blatta lateralis_, Tadzhikistan (Zmeev, 1940).

_Experimental vectors._--_Periplaneta americana_, Gold Coast Colony (Macfie, 1922).

_Polyphaga saussurei_, U.S.S.R. (Zmeev _in_ Pavlovskii, 1948).

Cockroaches, Venezuela (Tejera, 1926).

Family PARVOBACTERIACEAE

=Bacteroides uncatus= Eggerth and Gagnon

_Habitat._--Probably intestinal canal of mammals; from human feces.

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): From intestinal canal.

* =Brucella abortus= (Schmidt and Weis) Meyer and Shaw

_Experimental vectors._--_Periplaneta americana_, U.S.A. (Ruhland and Huddleson, 1941).

=Fusiformis lophomonadis= Grassé

_Habitat._--Surface of a flagellate (_Lophomonas striata_) which lives in the intestine of cockroaches (Breed et al., 1948; Grassé 1926, 1926a).

* =Malleomyces mallei= (Zopf) Pribram

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

* =Pasteurella multocida= (Lehmann and Neumann) Rosenbusch and Merchant

_Experimental vectors._--_Blatta orientalis_, Germany (Küster, 1902, 1903); Italy (Cao, 1906).

* =Pasteurella pestis= (Lehmann and Neumann) Holland

_Natural vectors._--_Blatta orientalis_, Hongkong (Hunter, 1906).

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898); Germany (Küster, 1903).

_Blattella germanica_, Germany (Jettmar, 1927).

_Leucophaea maderae_ and _Periplaneta americana_, Philippine Islands (Barber, 1912).

Family BACTERIACEAE

[cross] =Bacterium alkaligenes= Nyberg

_Natural vectors._--_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948): From intestinal tract.

[cross] =Bacterium delendae-muscae= Roubaud and Descazeaux

_Source._--Diseased fly larvae.

_Experimental infection._--Cockroach, France (Roubaud and Descazeaux, 1923): Organism pathogenic to cockroach when injected.

=Bacterium haemophosphoreum= Pfeiffer and Stammer

_Habitat._--Diseased larvae of _Mamestra oleracea_.

_Experimental infection._--_Blatta orientalis_ and _Blattella germanica_, Germany (Pfeiffer and Stammer, 1931): Organism pathogenic, when injected, to eight _B. orientalis_ and two _B. germanica_.

=Coccobacillus cajae= Picard and Blanc

_Experimental host._--_Blatta orientalis_, France (Picard and Blanc, 1913): The organism was pathogenic to _B. orientalis_ when injected.

Family BACILLACEAE

* =Bacillus anthracis= Cohen emend. Koch

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898, 1906); Germany (Küster, 1903).

[cross] =Bacillus bütschlii= Schaudinn

_Habitat._--_Blatta orientalis_, Germany (Schaudinn, 1902): Isolated from intestinal tract. Three percent of the cockroaches from Berlin bakeries were infected.

=Bacillus cereus= Frankland and Frankland

_Synonymy._--_Bacillus albolactis._

_Habitat._--Soil, dust, milk, plants.

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949): From feces.

_Periplaneta americana_, U.S.A. (Hatcher, 1939): In feces.

_Experimental host._--_Periplaneta americana_, U.S.A. (Babers, 1938): The cockroaches died within 96 hours after being injected with 10^{-3} ml. of a 24-hour broth culture.

=Bacillus circulans= Jordan

_Habitat._--Soil, water, dust.

_Natural vectors._--_Blattella germanica_, U.S.A. (Janssen and Wedberg, 1952): From intestine and feces.

[cross] =Bacillus flacheriae= (Hoffman)

_Source._--Diseased nun moth larvae.

_Experimental infection._--_Blatta orientalis_, Europe (Filatoff, 1904): The organism was not pathogenic when fed to the cockroach, but killed the insects when injected into the body cavity; after the insects died Filatoff reisolated this pathogen together with another bacillus from the cadavers. He succeeded in culturing the new microorganism and found it to be pathogenic when injected into, but not when fed to, the cockroaches. The diseased insects became sluggish, failed to eat or drink, turned over on their backs, their extremities became totally paralyzed, and they finally died.

=Bacillus megaterium= De Bary

_Habitat._--Soil, water, decomposing materials.

_Natural vectors._--_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948): From intestinal tract.

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898): Organism recovered, apparently unchanged, from intestinal contents.

[cross] =Bacillus monachae= (von Tubeuf) Eckstein

_Synonymy._--_Bacterium monache._

_Source._--Diseased larvae of nun moth, _Lymantria monacha_.

_Experimental infection._--_Blatta orientalis_, Europe (Filatoff, 1904): Organism pathogenic to the cockroach when injected but not when fed.

[cross] =Bacillus periplanetae= Tichomiroff

_Habitat._--_Blatta orientalis_, U.S.S.R.? (Tichomiroff, 1870[?], _in_ Filatoff, 1904): The infected insects suffered from a diarrhea and the liquid feces were yellow-brown.

[cross] =Bacillus stellatus= Hollande

_Natural infection._--_Blatta orientalis_, France (Hollande, 1934): Organism observed regularly in the intestine (especially rectum). Extensive description given.

[cross] =Bacillus radiciformis=

_Experimental vectors._--_Blatta orientalis_, Italy (Cao 1898): Organism recovered, apparently unchanged, from intestinal contents.

* =Bacillus subtilis= Cohn emend. Prazmowski

_Natural vectors._--_Blaberus craniifer_, U.S.A. (Wedberg et al., 1949).

_Blatta orientalis_, Italy (Cao, 1898, 1906; Spinelli and Reitano, 1932); France (Sartory and Clerc, 1908); Poland (Nicewicz et al., 1946).

_Cryptocercus punctulatus_, U.S.A. (Hatcher, 1939).

_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948).

Cockroaches, U.S.A. (Longfellow, 1913).

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898, 1906).

"=Bacillus subtilis= group"

_Natural infection._--_Blatta orientalis_, Italy (Ronzoni, 1949): Isolated from oöthecae.

[cross] =Bacillus tritus= Batchelor

_Habitat._--Isolated from feces (man?).

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): Isolated from intestinal tract.

* =Clostridium feseri= Trevisan

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

=Clostridium lentoputrescens= Hartsell and Rettger

_Habitat._--Soil, intestinal tract of man.

_Natural vectors._--_Blatta orientalis_, Poland (Nicewicz et al., 1946): Isolated from intestinal tract.

* =Clostridium novyi= (Migula) Bergey et al. or

* =Clostridium sporogenes= (Metchnikoff) Bergey et al.

_Natural and experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

* =Clostridium perfringens= (Veillon and Zuber) Holland

_Natural vectors._--Cockroaches [presumably _Blatta orientalis_, _Blattella germanica_, and/or _Periplaneta americana_], Egypt (El-Kholy and Gohar, 1945).

* =Clostridium tetani= (Flügge) Holland

_Experimental vectors._--_Blatta orientalis_, Italy (Cao, 1898).

* =Clostridium= spp.

_Natural vectors._--_Periplaneta americana?_ ("_Blatella americana_"), England (Shrewsbury and Barson, 1948).

Order ACTINOMYCETALES

Family MYCOBACTERIACEAE

* =Mycobacterium avium= Chester

_Experimental vectors._--_Blatta orientalis_, U.S.S.R. (Ekzempliarskaia _in_ Pavlovskii, 1948).

=Mycobacterium friedmannii= Holland

_Habitat._--Parasitic in turtles and possibly sparingly distributed in soils.

_Natural vectors._--_Periplaneta americana_, U.S.A., Texas (Micks, in Roth and Willis, 1957a): Organism isolated from batches of intestinal tracts of cockroaches collected at random.

* =Mycobacterium lacticola= Lehmann and Neumann?

_Natural vectors._--_Periplaneta americana_, U.S.A. (Leibovitz, 1951).

* =Mycobacterium leprae= (Armauer-Hansen) Lehmann and Neumann

_Natural vectors._--_Blattella germanica_, Southern Rhodesia and Kenya (Moiser, 1945, 1946, 1946a; Anonymous, 1946).

_Periplaneta americana_ and _Periplaneta australasiae_, Formosa (Arizumi, 1934, 1934a).

Cockroaches, Venezuela (Tejera, 1926); Belgian Congo (Radna, 1939).

_Experimental vectors._--_Blatta orientalis_, Europe (Paldrock _in_ Klingmüller, 1930); Nyasaland (Lamborn, 1940).

_Blattella germanica_, Europe (Paldrock _in_ Klingmüller, 1930); Southern Rhodesia and Kenya (Moiser, 1945, 1946, 1946a, 1947; Anonymous, 1946).

_Nauphoeta cinerea_, Nyasaland (Lamborn, 1940).

_Periplaneta americana_, Gold Coast Colony (Macfie, 1922); Formosa (Arizumi, 1934, 1934a).

_Periplaneta australasiae_, Formosa (Arizumi, 1934, 1934a).

Cockroaches, Belgian Congo (Radna, 1939); Venezuela (Tejera, 1926).

* =Mycobacterium lepraemurium= Marchoux and Sorel

_Experimental vectors._--Cockroaches, Belgian Congo (Radna, 1939).

* =Mycobacterium phlei= Lehmann and Neumann

_Natural vectors._--_Periplaneta americana_, U.S.A. (Leibovitz, 1951; Micks _in_ Roth and Willis, 1957a).

* =Mycobacterium piscium= Bergey et al.

_Natural vectors._--_Periplaneta americana_, U.S.A. (Leibovitz, 1951).

_Experimental vectors._--_Blatta orientalis_, U.S.S.R. (Ekzempliarskaia _in_ Pavlovskii, 1948).

* =Mycobacterium tuberculosis= (Schroeter) Lehmann and Neumann