Response of Ooencyrtus fecundus (Hym., Encyrtidae) to deprivation of host Eurygaster integriceps (Hem., Scutelleridae) eggs

The common sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), is a major pest of wheat and barley in Iran. Egg parasitoids (Hymenoptera: Scelionidae and Encyrtidae) represent the most promising natural enemies of this pest. However, these parasitoids often experience host absence early in the season. This study evaluated the effects of different host-deprivation intervals on Ooencyrtus fecundus Ferrière and Voegele (Hymenoptera: Encyrtidae), a widespread egg parasitoid of E. integriceps. Experiments were conducted under constant environmental conditions (۲۵ ± ۱ °C, ۵۰ ± ۱۰% RH, and a ۱۶L:۸D h photoperiod) with five host-access regimes: continuous access (control), access every other day, every third day, once per week, and full access following a seven-day deprivation period. Parasitism rate decreased as the deprivation interval increased, with the strongest negative effects observed in the once-per-week treatment. Partial compensation occurred during host-access days across all treatments. Females showed substantial recovery when given unlimited access following a long deprivation. Thus, early-season host delays are unlikely to threaten the biological control of the common sunn pest, as O. fecundus can compensate for lost opportunities during subsequent access. Nonetheless, intermittent host availability may negatively affect parasitoid performance.

کلیدواژه ها:

Compensation ، parasitism ، Enhancement ، Environmental constraints ، Encyrtidae ، Hymenoptera