IT 



proved to support the "best development of the larvae when 

 "bacteria were the only source of food. Sarclna lutea was 

 of little value, while Escherichia coli , Bacillus subtilis . 

 Bacillus mycoides , Aerobacter aerogenes , and Pseudomonas 

 fluorescens were of equal value. In media inoculated with 

 Pseudomonas ( pyocyaneus ) aeruginosa the toxic products of 

 this organism rapidly killed the larvae. Rozeboom's 

 attempts to grow mosquito larvae in the absence of "bacteria 

 were unsuccessful. Trager (l935 a ); "b) obtained normal 

 development of the larvae of Aedes aegypti in the absence 

 of living microorganisms. He used a medium consisting of 

 a standard autoclaved protein-free liver extract with 

 autoclaved yeast. He demonstrated that the la.rvae require 

 two accessory food substances. One is present in yeast 

 and aqueous yeast extracts, egg white, and wheat. It is 

 heat- and alkali -stable and is not adsorbed "by fuller's 

 earth. The other is present in large amounts in purified, 

 liver extracts rich in the anti -pernicious anemia principle. 

 It is heat-stable hut cannot withstand the action of 

 alkalis. In a slightly acid solution it is almost com- 

 pletely adsorbed "by fuller's earth. Interestingly enough, 

 it has "been found (Trager, Miller, and Khoads, 1938) that 

 a substance, possibly flavine or a flavine compound, 

 occurs in extracts prepared from urine of normal persons 

 or patients with aplastic anemia or leukemia which en- 

 hances the growth of larvae of Aedes aegypti . 



A relationship similar to that -of the mosquito larvae 

 in contaiminated water is suggested "by von Wolzogen Kuhr 

 (1932) with the larvae of Chironomus plumosus which fre- 

 quents sandfilters in the summer. This was attributed to 

 the presence in the filters of Pseudomonas fermentans upon 

 which the larvae supposedly fed. A similar situation was 

 described "by Dyson and Lloyd (1933) in sewage "beds. 



One of the first to advance the idea that "bacteria are 

 indispensable to the growth of certain insects was Bogdanow 

 (1906) who found that the larvae -of Calliphora vomitoria 

 fail to develop in the absence of microorganisms. Later 

 (1908) he stated that the larvae require a definite and 

 fairly simple bacterial flora. Sterile larvae on sterile 

 food never developed normally , t although some of them 

 reached the pupal stage. Weinland (1907), however, showed 

 that the larvae of Calliphora are able to digest meat with- 

 out the assistance of bacteria. Bogdanow also found that 

 larvae of the house fly, Musca domes tica , can be bred on 

 starch paste or gelatin, but only in the presence of molds 

 and bacteria. Wollman (1921) reported that microbe-free 

 cultures of flies can be maintained indefinitely, as can 



