An evaluation on host discrimination and superparasitism in Trissolcus semistriatus (Nees, 1834) (Hymenoptera: Scelionidae), egg parasitoid of Eurygaster integricepsPut., 1881 (Hemiptera: Scutelleridae)

Abstract

Trissolcus semistriatus (Nees, 1834) (Hymenoptera: Scelionidae) is the most common and important egg parasitoid of Eurygaster integriceps Put., 1881 (Hemiptera: Scutelleridae). This study was conducted to determine discrimination E. integriceps eggs parasitized by either self or a conspecific female of T. semistriatus in choice and no-choice tests, and to establish effect of adult parasitoid density and host density on parasitism in the laboratory in 2016. Female parasitoids did not superparasitize self-parasitized host eggs. However, superparasitism of 18% (significantly lower than the 81% parasitism rate) of the eggs parasitized by another female occurred within 1 h of first parasitism. Superparasitism was significantly lower at 1% in no-choice tests than the 23% recorded in choice tests within 24 h of first parasitism. Parasitism significantly decreased with increasing host egg number, but parasitism did not change with increasing parasitoid density. Therefore, it is concluded that T. semistriatus can discriminate between parasitized and unparasitized host eggs, with superparasitism infrequent when females encounter preparasitized host eggs within 48 h of first parasitism.