The Effects of Gamma Radiation on the Biology and Behavior of Adult Ips confusus (LeConte) (Coleoptera: Scolytidae)

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Abstract
Sterilization of male and female Ips confusus (Coleoptera: Scolytidae) exposed to gamma radiation (Co60) as newly emerged adults was almost complete at levels exceeding 7500 r and 10,000 r, respectively. Mating behavior of males as expressed by sperm transfer was unaffected by dosages up to 60,000 r. The capacity of beetles of either sex to establish galleries was not affected significantly below this dosage, but female gallery pattern was altered above 15,000 r. Longevity was reduced at levels greater than 5000 r. LD50 for males occurred at 11.5 days at 7500 r and 29 days in the controls. Mortality of progeny resulting from males irradiated at substerilization levels was higher than in the controls. The dosage to achieve significant population reduction with minimum effect on longevity and other biological activity is estimated to lie between 6000 and 7500 r.These studies indicate that this sterilization technique may have promise in the control of bark beetles. The necessity for rearing large numbers on artificial media could be circumvented by mass trapping utilizing their natural sex attractant and by mass rearing in cut host material in the laboratory.