محمد علی میر حسینی

Habrobracon hebetor (Say) is a parasitoid of vari ous Lepid optera including Helicoverpa armige ra(Hübne r), a key pest of different crops and vegetables. The devel-opment of both H. armige ra and H. hebetorwere simultane ously evaluated against a wide range of constant temperatures (10, 15, 17.5, 20, 25, 27.5, 30, 35, 37.5 and 40 °C). Helicoverpa armige ra comple ted its de velop ment from egg to adult within a temp era-ture range of 17.5 –37.5 °C andH. hebe torcomple ted its life cycle from egg to adult within a temperature range of 15– 40 °C. Based on the Ikemoto and Takai model the develop mental thresho ld (T o ) and thermal constant (K ) to com plete the immature stages, of H. armige ra were calculated as 11.6 °C and 513.6 DD, respectively, and 13 °C and 148 DD, respectively, for H. hebet or. Analyti s/Briere-2 and Ana lytis/Br iere-1 were adjudged the best non-linear models for prediction of pheno logy ofH. armige ra and H. hebetor, respectively and enab led estimation of the optimum (T opt ) and max-imum temp erature ( T max ) for develop ment with values of 34.8, 38.7, 36.3, and 43 °C for host and the parasitoid, respectively. Parasitisation by H. hebetorwas maximal at 25 °C but occu rred even at 40 °C. This study sugge sts altho ugh high temperature is limiting to insects, our estim ates of the upper therm al limits for both species are high-er than previously estimated. Some biological control of H. armigera byH. hebetormay persist in tropical areas, even with increasing temperatures due to climate chang e.