Determination of the most appropriate time for interrupting diapause of sunn pest using the juvenile hormone mimic admiral (Pyriproxyfen) to collect eggs for Trissolcus grandis

The Sunn Pest (Eurygaster integriceps Put.) is the most important pest of wheat and barley fields in Iran. For mass rearing of egg parasitoids, an appropriate host is necessary. One of the hosts is the egg of sunn pest. Diapause of sunn pest is one of the limitations for egg production. The aim of this study was to inhibit the diapose of sunn pest with the use of juvenilhormon mimic (admiral) and to determine the procentae parasitism of the egg by Trissolcusgrandis Thomson. Collected Eurygasterintegriceps adults from overwintering sites in July, August, September and, October, were maintained on dry wheat grains and water was provided with a piece of wet cotton in laboratory conditions at 25± 3 C^o, 50- 60% RH, and 16:8 (L:D). This experiment included 4 treatments (July, August, September and October) with 4 replications. Ten males and ten females of Eurygasterintegriceps were released in each replication in a ventilated cage (20*30*15cm). Admiral 10% (at the concentration of 0.002) was applied topically on the ventral abdomen of Sunn pest. Furthermore, a control treatment without admiral was considered. The data were analyzed using SPSS and the means were compared by Duncans multiple range test. Results indicated that admiral interrupted the diapose of sunn pest in the above mentioned months, and induced mating and oviposition. When different months were compared the highest percentage of ovipsition (39.6%), the lowest percentage of unhatched eggs (17.25%), the lowest percentage of dead adults (10%) and the highest percentage of egg parasitism (60%) were observed in July . It could be concluded that July is the most appropriate time for interrupting diapause of Eurygasterintegriceps which can be used for the mass reerying of Trissolcusgrandis. In adation, no parasitoid adults emerged from the parasitized Eurygasterintegriceps eggs.