اثرات کشندگی سه حشره‌کش شیمیایی روی زنبور پارازیتویید تخم سن گندم (Thomson) Trissolcus grandis

Trissolcus grandis (Thomson) (Hym.: Platygastridae) is one of the most important egg parasitoid of Sunn pest Eurygaster integriceps Puton. This study evaluated lethal effects of recommended field doses of three synthetic compounds included: (deltamethrin+thiacloprid (Proteus® OD 11%) 1000 ml/ha, lambda-cyhalothrin (Karate-zeon® CS 10%) 75 ml/ha and deltamethrin (Decis® EC 2.5%) 300 ml/ha on the adult and different immature stages of T. grandis under the laboratory conditions. Data were analyzed by SAS software and mean of treatments were compared by SNK test at 5% probability level. Results indicated that all insecticides caused 100% mortality on the adult wasps. Among the studied insecticides, the highest and the lowest mean percentage emergence of T. grandis female were observed in eggs treated with lambda-cyhalothrin and deltamethrin+thiacloprid insecticides, respectively, at all immature stages (first and second instars and pupa). In our study, deltamethrin+thiacloprid, deltamethrin and lambda-cyhalothrin were categorized in groups 3, 2, and 2 based on )IOBC( categorization with the decreased percentage emergence of adult by 91.16, 76.10 and 34.77%, respectively. Also in assessing parasitism activity, the adult wasps emerged from the eggs which had been dipped in lambda-cyhalothrin insecticide at various immature stages, showed the highest mean percentage of parasitism. Therefore, according to our results utilization of deltamethrin+thiacloprid and deltamethrin would be not recommended in chemical control of overwintered adult pest. These insecticides will probably reduce the populations and diversity of T. grandis in the sprayed area due to their higher stability and repellency for parasitoid wasps. Lambda-cyhalothrin (Karate-zeon®) may be selective insecticide to the control of pest, because in addition to being effective on overwintered adults, it also did show less negative effect on the emergence of adults after egg treatment and on the parasitism activity of the emerged parasitoid wasps as compared with the other two studied insecticides.