Intraguild interactions between two egg parasitoids exploring host patches

Abstract

Intraguild interactions between two egg parasitoids, Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Hymenoptera: Encyrtidae), exploring egg masses of the Southern Green Stink Bug (SGSB) Nezara viridula (Heteroptera: Pentatomidae), were investigated in laboratory conditions by single, simultaneous and sequential host attack experiments. Mortality of N. viridula eggs was higher in simultaneous and sequential releases compared to single species releases. In simultaneous host exploitations, T. basalis females displayed an aggressive behavior against O. telenomicida females. The outcome of multiparasitism showed that interspecific larval competition was dominated by O. telenomicida regardless of the sequence in which oviposition occurred and which parasitoid was or was not simultaneously released in the patch. Finally, O. telenomicida can successfully develop in hosts already parasitized by T. basalis up to seven days earlier, acting as a facultative hyperparasitoid, so that intraguild predation (IGP) also occurred. The ecological factors that allow species coexistence and the role played by competition in biological control\ud programs are discussed

Multiparasitism of stink bug eggs: competitive interactions between Ooencyrtus pityocampae and Trissolcus agriope

“…Trissolcus females use an oviposition pheromone to mark parasitized eggs (Rosi et al 2001), whereas eggs parasitized by Ooencyrtus females have respiratory stalks protruding from the host chorion that can be used for discrimination (Takasu and Hirose 1988 (Buschman and Whitcomb 1980;Corrêa-Ferreira 1986;Corrêa-Ferreira and Moscardi 1995;Ehler 2002;Hoffmann et al 1991;Shepard et al 1994, Cusumano et al 2011. For example, Amarasekare (2000a;2000b) studied competition and coexistence between Trissolcus murgantiae (Ashmead) and Ooencyrtus johnsonii (Howard) and found that both species in combination inflicted substantial mortality on eggs of Murgantia histrionica (Hahn) (Heteroptera: Pentatomidae).…”

Interspecific extrinsic and intrinsic competitive interactions in egg parasitoids

“…On the contrary, there are also studies demonstrating an asymmetrical outcome, i.e. one species is superior intrinsically with respect to another species and wins the contest regardless the order of ovipositions (Subba Rao and Chacko 1961;Lee 1979;Kfir and van Hamburg 1988;Sjaarda 1989;Weber et al 1996;Cusumano et al 2011Cusumano et al , 2012 (Table 2).…”

“…Some Ooencyrtus and Trichogramma species display an advantage thanks to their ability to develop as facultative hyperparasitoids of platygastrid wasps (Strand and Vinson 1984;Strand 1986;Sjaarda 1989;Mizutani 1994;Cusumano et al 2011). Even if intrinsic competition and facultative hyperparasitsm are two distinct ecological interactions, they both critically depend on the time interval between parasitoid ovipositions and they often result in a similar outcome (the death of the host as well as of the competitor).…”

“…On the contrary, O. nezarae emerges when it attacks hosts 3-7 days after either G. japonicum or G. nigricorne suggesting that the encyrtid acts as a facultative hyperparasitoid (Mizutani 1994). In other cases, a parasitoid species can be intrinsically superior both when acting as primary or secondary parasitoid (Sjaarda 1989;Cusumano et al 2011). For example, interspecific larval competition between O. telenomicida and T. basalis was dominated by the former regardless of the sequence in which oviposition occurred and if parasitoids were, or were not, simultaneously released in the patch: O. telenomicida wins even when T. basalis parasitized an egg mass up to seven days before .…”

“…In these circumstances, facultative hyperparasitoids can overcome the gap between ovipositions and develop on those parasitoid species that have totally consumed the host resources. Cusumano et al (2011Cusumano et al ( , 2012 The role of the host age in the outcome of interspecific competition has been investigated between Gonatocerus ashmeadi Girault and Gonatocerus triguttatus Girault, two egg parasitoid of Homalodisca coagulata (Say) (Irvin et al 2006). Even though G. triguttatus often outcompeted G. ashmeadi, the relative success in terms of offspring production is also affected by the order and the time interval between oviposition as well as by the host egg mass age.…”