BIOTIC ASSOCIATIONS OF COCKROACHES — ROTH & WILLIS lOI 



The growth rates of Periplaneta aniericana and Blattella gcrmanica 

 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 synthe- 

 sized 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. How- 

 ever, 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 Peri- 

 planeta americana) by oxygenation at 3.5 atmospheres. The ciliates 

 Nyctotherus and Balantidium, flagellates Lophomonas and Poly- 

 mastix, the amoeba Endamoeba hlattae, and three unidentified pro- 

 tozoa 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, Lopho- 

 monas 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 punctu- 

 latus depends upon certain intestinal protozoa for survival ; these 

 protozoa utilize as food the wood ingested by this cockroach. The 



