Studies on the Nematode Parasites of the American Cockroach, Periplaneta Americana

Abstract

The American cockroach, Per planeta americana, serves as the host for at least three species of parasitic nematodes. Two of these parasites, Hammerschmidtiella diesingi (Hammerschmidt, 1838) Chitwoou, 1932, and Leidynema appendiculata (Leidy, 1850) Chitwood, 1932, are common inhabitants of the intestinal tracts of 85 per cent of the cockroaches which were collected on the Kansas State College campus. In some of these insects over 30 mature worms, each about 3 mm. in length. were found. Because the worms are very transparent the process of egg laying can readily be observed under a microscope. At the time of extrusion the eggs are undeveloped or in the very earliest stages of cleavage. Embryonic development is very rapid and under optimum conditions a motile tadpole-like stage is reached in 36 hours. A few days later a quiescent, non-motile embryo is formed in the egg. Experiments show that the latter is the infective stage and that transmission is direct. All the attempts to make the egg hatch in artificial media were negative, however material for studying the development and growth was obtained from experimentally Infested cockroaches. From our present data it appears that the nematodes attain sexual maturity in 20 or 30 days after artificial infestation.