Biological effects of two eco-friendly novel formulations of a pyrethroid insecticide lambda-cyhalothrin on the parasitoid wasp Trissolcus grandis (Thomson)

Eurygaster integriceps Puton is an important pest of wheat and barley in Iran and the Middle East. Chemical control of the pest should be carried out by selective insecticides to conserve its natural enemies such as Trissolcus grandis (Thomson). In this research, the lethal effects of field recommended doses of two new formulations from lambda-cyhalothrin including Karate-zeon® (CS 10%) and Hef-lambda® (SC 5%) were studied on the mature and different immature stages of T. grandis under the laboratory conditions. Contact of the adult wasps with sprayed areas by both insecticides caused 100% mortality. Parasitized eggs containing first instar (at the third day of parasitism), second instar (at the fifth day of parasitism) and pupa stage (at the eighth day of parasitism) were dipped into insecticide solutions. At all immature stages and for both insecticides, the highest mean percent emergence of T. grandis female was observed in SC 5% treated eggs. Treatment of eggs with both insecticides at different immature stages of parasitoid did not show any negative effect on the parasitism activity. However, Hef-lambda®, was proved to be more selective insecticide, because it showed less negative effect on the number of adults that emerged after egg treatment. According to the results of present study, Hef-lambda® can be considered as a less hazardous selective and eco-friendly insecticide in the Sunn pest management.