Study on egg parasitoids (T. agriope & Psix sp.) using eggs of four bug species in laboratory conditions

The pistachio green stink bugs are the most important pests in the pistachio growing areas. The egg parasitoids are considerable biocontrol agents. Five species of egg parasitoid of the Scelionid family were collected from pistachio pentatomid bug eggs. Trissolcus agriope and Psix sp. are the dominant species in the pistachio orchards in Kerman province. In order to detect the percentage of parasitism by T. agriope and Psix sp. on the eggs of Brachynema signatum, Acrosternum heegeri, Croantha ornatula and Graphosoma lineatum, parasitic eggs were collected from nature. Then, for detection of daily parasitism, 100 eggs of different host bugs for 24 hours, were offered to one of each egg parasitoid species. In order to detect the host preference, 50 eggs of each wasp species for 24 hours, were offered to one of the each parasitoid. For detection of the male copulation capability, first male emergences of each egg parasitoids wasp were exposed to 30 female and then this female released on the one newly egg mass. In order to detect the most suitable age of bug eggs for parasitism, 50 eggs with different ages were offered to one of each parasitoid species. For detection of sex ratio, individual and 10, 15, 20, 25 and 30 egg mass of each bugs were offered to one pair of each parasitoid species. The experiments were carried out under controlled conditions (28 ± 1ºC, 65 ± 5% and 16 h L: 8 h D). The results show that, highest egg parasitism by the Psix sp. and T. agriope belonging to C. ornatula and B. signatum egg mass with 216.51 and 209.11 egg with 18 day longevity, respectively. The results of host preference experiments indicate that, percentage parasitism each of egg parasitoids on the B. signatum, A. heegeri and C. ornatula no significant differences, but on the C. ornatula have significant differences. Highest percentage of parasitism in the all of bugs occurred in 24 h old eggs and after 36 hours the percentage of parasitism decreases extremely. Highest copulation of T. agriope and Psix sp. obtained on the C. ornatula eggs with 25.5 and 27.25 female respectively. Sex ratio increases with number of eggs in egg mass. Data obtained show that T. agriope population on the B. signatum eggs with higher growth and reproduction rates and lower growth time were a more efficient host than the other bugs.