Abstract:
Trissolcus grandis (Thomson) (Hymenoptera: Scelionidae) is the most important egg
parasitoid of the common sunn pest, Eurygaster integriceps Puton (Hemiptera:
Scutelleridae) in Iran. Demographic characteristics may be used for preliminary
screening of parasitoid species or populations as well as for predicting their efficiency
under different physical conditions in the field. In this study, the demography of two
northwestern populations of T. grandis was studied under five constant temperatures
including 20, 23, 26, 29, and 32±1°C, at 50±5% RH and 16:8 h (L: D) photoperiod. The
two populations responded differently to the temperatures, thus, many life history
parameters were significantly affected not only by temperature itself but also in
interaction with population. The highest value of intrinsic rate of increase for the Marand
population was 0.344±0.057 females/female/day that occurred at 26°C. The same rate for
the Tabriz population increased regularly with temperature increase and the maximum
value (0.368±0.063) was obtained at 29°C. Further increase in temperature led to a
negligible change in the value of this parameter. As a whole, the Marand population
seemed to be adapted to cooler conditions compared to the Tabriz population
Keywords: Egg parasitoid, Eurygaster integriceps, Intrinsic rate of increase, Life history
