INFECTIVITY OF NEMATODES, NEOAPLECTANA SPECIES, FOR LARVAE OF WEEVIL HYLOBIUS PALES, AFTER REARING IN SPECIES ISOLATION

Three nematode strains (Neoaplectana glaseri, DD-136 Neoaplectana carpocapsae, and Czech Neoaplectana carpocapsae) that are natural parasites of insects but that have been laboratory-reared many generations in species isolation (i.e., axenically) were tested for infectivity. The trial hosts were larval weevils (Hylobius pales) raised from eggs in species isolation (i.e., without symbiotes); 34% became infected with nematodes. Specifically, 35% of weevils exposed to N. glaseri, 31% of weevils exposed to DD-136 N. carpocapsae, and 69% of weevils exposed to Czech N. carpocapsae were parasitized. Since all larval worm stages and reproducing adults were found in some weevils, the clean" insects were judged to be suitable and sufficient hosts for these nematodes. A pathogenic potential of clean nematode infections was suggested but not proved because of the generally short survival of weevils in species isolation cultures. © 1969."