Parasitism of diapausing pink bollworm Pectinophora gossypiella (Lepidoptera: Gelechiidae) larvae by entomopathogenic nematodes (Nematoda: Steinernematidae, Heterorhabditidae)

Diapausing larvae of Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), were exposed to entomopathogenic nematodes (Nematoda: Steinernematidae; Heterorhabditidae) at a dosage of 100 or 200 infective juveniles (IJ) per larva. No significant differences between infection of Steinernema riobrave (strain 355) Cabanillas, Poinar and Raulston, and Heterorhabditis bacteriophora (strain Cruiser) (Poinar) were observed after either 6-d or 9-d of incubation. No significant difference in infection levels occurred due to increasing dose. Greatest insect mortality occurred due to parasitism by S. riobrave (355). In a second assay, diapausing larvae of P. gossypiella were exposed to S. riobrave (355), Steinernema carpocapsae (strain Kapow) (Weiser), H. bacteriophora (strain Lawn Patrol), or H. bacteriophora (Cruiser) at dosages of 50, 100,200, or 400 IJs per larva. S. carpocapsae and H. bacteriophora (Cruiser) infected larvae at significantly higher rates compared with H. bacteriophora (Lawn Patrol) and S. riobrave. A significant difference in infection levels occurred due to nematode dose. In a third assay cotton bolls infested with diapausing P, gossypiella were exposed to S, riobrave (355), or H. bacteriophora (Cruiser). Boxes were prepared with bolls buried 5 cm below the soil surface or bolls laid on the soil surface. Boxes also were incubated at constant temperature or exposed to ambient seasonal temperatures and light. H. bacteriophora (Cruiser) infected larvae at significantly higher rates compared with S. riobrave (355). Significant differences in infection levels occurred due to the location of the boll placement and the incubation temperature.