Pectinophora gossypiella (Lepidoptera: Gelechiidae): Susceptibility of F₁ Larvae from Irradiated Parents to Entomopathogenic Nematodes (Rhabditida: Steinernematidae, Heterorhabditidae)

We studied the interactions between F₁ progeny of Pectinophora gossypiella (Saunders) adults irradiated in the pupal stage and entomopathogenic nematodes. Both sexes of pink bollworm pupae were exposed to 4, 8, 12, or 16 krad substerilizing radiation doses irradiated using a ⁶⁰Co source. The F₁ larvae were tested in a sand bioassay for susceptibility to Steinernema riobravis Cabanillas, Poinar & Raulston, S. carpocapsae (Weiser), and 2 strains of Heterorhabditis bacteriophora (Poinar). The numbers of infecting nematodes were counted after 48 h. Increasing parental radiation dose significantly increased F₁ larval susceptibility to S. riobravis and H. bacteriophora, but decreased susceptibility to S. carpocapsae. This difference in susceptibility may be caused by the sedentary nature of larvae from parents receiving higher levels of irradiation, combined with the passive ambush tactics used by S. carpocapsae to acquire an insect host. The need to sustain the F₁ population of pink bollworm for sterility promotion and subsequent population collapse suggests S. carpocapsae to be an ideal entomopathogenic nematode to be used in conjunction with inherited sterility control methods.