SEASONAL OCCURRENCE AND HOST SPECTRUM OF EGG PARASITOIDS ASSOCIATED WITH SOYBEAN STINK BUGS

In surveys conducted in soybean fields of Northern Parana State, Brazil, 20 species of microhymenopterous parasitoids were observed as egg parasitoids of stink bugs, mainly represented by the families Scelionidae, Encyrtidae, Eurytomidae, and Pteromalidae. When total parasitized eggs were considered for each host species, Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead were the most frequent and prevalent species, with Tr. basalis being preferentially associated with Nezara viridula (Linnaeus) (98%) and Piezodorus guildinii (Westwood) (44%), while Te. podisi was more prevalent on eggs of Euschistus heros (Fabricius) (73%), Podisus connexivus Bergroth (61%), and Dichelops melacanthus (Dallas) (50%). The parasitoids Gryon obesum Masner from eggs of N. viridula and Eu. heros and Trissolcus urichi (Crawford) from eggs of Edessa meditabunda (Fabricius), Eu. heros, and Thyanta perditor (Fabricius) mere recovered for the first time in Brazil, In the surveyed soybean areas, the natural parasitism was very high, reaching maximum values of 62% on N. viridula eggs, and 60 and 57% on Eu. heros and Pi. guildinii eggs, respectively. The parasitoids maintained reproductive activity on these hosts practically all year long, with higher populational densities from October to December and at the end of the soybean season (March-April). (C) 1995 Academic Press, Inc.