Interspecific competition between Trissolcus semistriatus Nees and Trissolcus simoni (Mayr.) (Hymenoptera: Scelionidae), egg parasitoids of the sunn pest

Trissolcus semistriatus Nees and T. simoni (Mayr.) (Hymenoptera: Scelionidae) are the most important and common natural enemies of the sunn pest [Eurygaster integriceps Put. (Hemiptera: Scutelleridae)]. This study was conducted to determine whether females of T. semistriatus and T. simoni multiparasitized previously parasitized E. integriceps eggs or not and to evaluate interspesific larval competition and adult competition between T. semistriatus and T. simoni. For this aim, half of host egg mass parasitized by one species and un-parasitized were provided to females of other species in choice tests, and a whole egg mass parasitized by one species were given to other species female in no choice tests. Multiparasitism experiments were applied after one hour, 24 h and 72 h from the first oviposition. To determine adult competition, one each female of T. semistriatus and T. simoni were released on two egg masses at the same time. All experiments were observed under a stereomicroscope. Multiparasitism rates for both T. semistriatus and T. simoni were significantly low in the eggs pre-parasitized by another female species in choice test and these rates decreased with the time from the first parasitism, whereas multiparasitism rates were higher in choice test than those of non-choice test. Emergence from multiparasitized eggs was greater for first parasitoid species than for second species. As a result of adult competition tests, female of T. semistriatus was found as a superior competitor than T. simoni