Seasonal Fluctuations in Egg Parasitoid Fauna of Sunn-Pest Eurygaster integriceps Puton in Wheat Fields of New Bonab County, East Azerbaijan Province, Iran

Abstract

Regarding strategic importance of wheat and occurrence of sunn pest (Eurygaster integriceps Puton), as an important pest of wheat in Iran, an efficient IPM program against the pest is needed for an acceptable production. Since natural enemies are one of the most important components in IPM programs, their identification is necessary for augmentation as well as conservation and enhancement purposes. Egg parasitoids are the most important biological control agents of sunn pest. Thus, identifying the combination of the species as well as studying their seasonal fluctuations were carried out in summer 2008 in New Bonab county, East Azerbaijan province, northwest of Iran. Egg traps were used for this purpose. Five species of the egg parasitoids belonging to Scelionidae and Encyrtidae were collected. Total parasitism rate was 2.6-22.59% (12.23% at average) in different dates. Trissolcus grandis (Thomson), Ooencyrtus fecundus Ferriere & Voegele and O. telenomicida (Vassiljev)were the most abundant species at different period of the season. This is the first record of O. fecundus from Iran. The other less frequent species were T. semistriatus (Nees), and T. djadetshko (Rjachovsky). T. grandis was the first species that observed in spring with a maximum parasitism rate of 12.76%. The two Ooencyrtus species however, preceded it at summer (Ooencyrtus fecundus, and O. telenomicida with maximum parasitism rates of 13.8 and 13.47%, respectively in different dates in July). There were significant difference of parasitism rates in different geographical parts of the area as the parasitism rate in the eastern fields was found higher than both southern and western ones. It seems that climatic factors are responsible for the observed changes both spatially and temporally and may act directly on the parasitoids or indirectly on hosts