Ecological and Biological Study of Two Species of Genus Trissolcus spp. The Egg Parasitoids on Sunn Pest Eggs in Syria

Sultan Sheikhmoss
General Commission for Scientific Agricultural Research-
Kameshli Research Center
Aleppo University, Faculty of Agriculture


Egg pararsitoids of sunn pest are among the most important natural enemies that contribute to the reduction of sunn pest populations, and the most important are those belonging to genus Trissolcus, family Scelionidae, and order Hymenoptera. As the two species Trissolcus vassilievi Mayer and Trissolcus grandis Thomson are the most common species attacking eggs of Eurygaster integriceps Put.(Hemiptera: Scutelleridae) in Syria. This study was conducted in two years 2006-2007. The results of the effects of constant temperatures showed that both species had seen semi-inactive at 15 Cand didnt parasitize on introduced eggs. At temperatures (20, 25 and 30±2 C) female longevity, average development time from egg to pre-pupal, average development time of females and males from egg to adult decreased for both parasitoids species, when temperature increased, the highest fecundity of female was 106.7 and 94.8 eggs recorded at 25 Cfor T. vassilievi and T. grandis respectively. Average percent of females and eggs hatching did not differ significantly among different temperature nor in the same species, while there was some superiority of T. vassilievi over T. grandis because of  its longevity and capability of parasitizining a higher number of sunn pest eggs. On other hand, there was superiority of T. grandis over T. vassilievi because of its short development period. when the effects of host insect were studied, Results showed that percent of parasitism, percent of adult emergence differ significantly when the eggs age was three days old for both parasitoids species, comparative with eggs age less one day and two days old, while the females percent and development time for males and females did not differ among different eggs age and in the same species, some superiority of eggs age less one day and two days comparative with three days old  because of  its  higher parasitism.
The results of impact of the density of sunn pest eggs and parasitoids at levels (10, 20, 30 and 40 egg/female; 50, 100 and 150 egg/5 females; and 100, 200 and 300 egg/10 females) showed that female fertility increased as number of the sunn pest eggs increased. There wasn’t significant differences in percent of hatch and females between the two species at tested densities of sunn pest eggs and parasitoids, the average development time of females and males from egg to adult differed significantly between the two species at tested densities of sunn eggs and parasitoids.