PECTINOPHORA-GOSSYPIELLA (LEPIDOPTERA, GELECHIIDAE) - SUSCEPTIBILITY OF F-1 LARVAE FROM IRRADIATED PARENTS TO ENTOMOPATHOGENIC NEMATODES (RHABDITIDA, STEINERNEMATIDAE, HETERORHABDITIDAE)

We studied the interactions between F-1 progeny of Pectinophora gossyp iella (Saunders) adults irradiated in the pupal stage and entomopathog enic nematodes. Both sexes of pink bollworm pupae were exposed to 4, 8 , 12, or 16 krad substerilizing radiation doses irradiated using a Co- 60 source. The F-1 larvae were tested in a sand bioassay for susceptib ility to Steinernema riobravis Cabanillas, Poinar & Raulston, S. carpo capsae (Weiser), and 2 strains of Heterorhabditis bacteriophora (Poina r). The numbers of infecting nematodes were counted after 48 h. Increa sing parental radiation dose significantly increased F-1 larval suscep tibility to S. riobravis and H. bacteriophora, but decreased susceptib ility to S. carpocapsae. This difference in susceptibility may be caus ed by the sedentary nature of larvae from parents receiving higher lev els of irradiation, combined with the passive ambush tactics used by S . carpocapsae to acquire an insect host. The need to sustain the F-1 p opulation of pink bollworm for sterility promotion and subsequent popu lation collapse suggests 8. carpocapsae to be an ideal entomopathogeni c nematode to be used in conjunction with inherited sterility control methods.