GAMMA-RADIATION SUSCEPTIBILITY OF STRAINS OF TRIBOLIUM-CASTANEUM (HERBST) RESISTANT AND SUSCEPTIBLE TO FENVALERATE

Gamma radiation susceptibility of adults of the fenvalerate-resistant strain of Tribolium castaneum (Herbst) (Coleoptera:Tenebrionidae) was studied under laboratory conditions. Selection for resistance to fenva lerate in adult beetles was carried out up to the sixth generation. In each generation of selection, adults of the fenvalerate-resistant str ain were evaluated for susceptibility to gamma radiation and compared with their fenvalerate-susceptible counterparts. Susceptibility to Co- 60 gamma radiation was evaluated on the basis of dosage-mortality (LD5 0) and time-mortality (LT50) responses. We found the LD50 values for t he fenvalerate-resistant and -susceptible strains to be 89.16 and 97.4 6 Gy respectively, showing no significant difference in susceptibility to gamma radiation. LT50 values were 7.58 and 17.20 days for the fenv alerate-resistant and -susceptible strains respectively, showing that mortality in the resistant strain occurred markedly earlier than in th e susceptible strain.