Temperature has a profound effect on performance and behavior of egg parasitoids. Egg parasitoids are a well-known alternative for the control of lepidopterous pests. Selected life history parameters of Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae), an established egg parasitoid species in Khuzestan- Southwest Iran, were appraised at eight constant temperatures (22.5, 25, 27.5, 30, 32.5, 35, 37.5, and 40°C) using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as the host. We found significant effects of temperature on the number of parasitized eggs, development time, sex ratio, progeny’s longevity, and fecundity. T. euproctidis developed on E. kuehniella eggs at all temperatures tested, but performed best at 32.5°C. At this temperature, they parasitized the most eggs, produced the most female progeny, and had high rates of survival. Our findings revealed that temperature significantly affected the longevity of female progeny and fecundity of T. euproctidis. A life table analysis confirmed that temperature resulted in optimal effects on T. euproctidis life history. Net reproductive rate (R₀) of T. euproctidis was different among the temperatures tested. The intrinsic rate of increase (r) was positively correlated with temperature from 22.5 to 32.5°C and then decreased from 35 to 40°C. Generation time (T) and doubling time (DT) decreased as temperature increased from 22.5 to 37.5°C and then increased at 40°C. These data suggest that this strain of T. euproctidis is adapted to high temperatures and harsh environmental conditions and has the potential to be used in integrated management programs in Southwest Iran.

Trichogramma euproctidis (Girault) is an egg parasitoid under consideration for mass production and augmentative biological control of major lepidopteran pests in Iran and other countries. The main objective of this research was to determine the effects of T. euproctidis female age and Ephestia kuehniella Zeller egg age on life history parameters of T. euproctidis. Experimental design involved exposing 1-, 2-, 3-, or 4-d-old E. kuehniella eggs to 1-, 2-, 3-, or 4-d-old T. euproctidis females in glass test tubes. Results indicated that host egg age and parasitoid female age interacted significantly to improve parasitism rate, progeny emergence rate, sex ratio, longevity, and fecundity of T. euproctidis. The age of T. euproctidis females affected parasitism rate; 1-d-old females, rather than the other ages, parasitised more E. kuehniella eggs. The highest mean total fecundity (81.62 eggs) was recorded from adult progeny produced by 1-d-old T. euproctidis females reared from 1-d-old E. kuehniella eggs. Trichogramma euproctidis development time increased as the age of E. kuehniella eggs increased, but the parasitoid female age and host egg age interaction was not significant. A life table analysis confirmed the results that 1-d-old T. euproctidis females and 1-d-old E. kuehniella eggs resulted in optimal effects on T. euproctidis life history. This study implies that mass rearing systems designed to expose young-aged T. euproctidis females to young-aged E. kuehniella eggs would maximise T. euproctidis progeny production.

The successful mass-rearing of potential biological control agents is a prerequisite for sustainable pest control. In this study, the performance of 3 Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae) populations collected from different locations in Khuzestan (Southwest Iran) were evaluated to optimize the egg parasitoid mass-rearing for augmentative biological control of lepidopteran pests. We aimed to investigate the effects of both population origin and host quality on biological traits of ovipositing females (number of parasitized eggs) and of their progeny (development time, survival rate, sex ratio, longevity, and fecundity). The effect of host quality was assessed by allowing the parasitoid to oviposit into 1, 2, 3, or 4-day-old Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. The 3 T. euproctidis populations developed successfully regardless the age of the host eggs. However, we found significant variation among populations and a strong influence of host quality on the traits investigated. Progeny performance in all populations decreased with increasing host age. The best-performing population (collected in Mollasani) showed the highest parasitization rate, highest survival rate, and progeny sex ratio with the greatest percentage of females. A life table corroborated these findings with superior estimates of the net reproductive rate (R₀), intrinsic rate of increase (r), and reduced generation time (T) for the Mollasani population on 1-day-old host eggs. We conclude that ample variation exists among T. euproctidis populations and that rearing the Mollasani population on young rather than old eggs of E. kuehniella would be recommended to implement the biological control programs to target lepidopteran pests in Southwestern Iran.