Interspecific competition between Eupelmus vuilleti and Dinarmus basalis, two solitary ectoparasitoids of Bruchidae larvae and pupae
1993
Alebeek, F.A.N. | Rojas-Rousse, D. | Leveque, L.
Coexistence of two solitary ectoparasitoids of bruchids may be the result of counter-balanced competition. Some strategies in interspecific competition at the extrinsic level of female behaviour are identified. Dinarmus basalis (Rondani) (Hymenoptera; Pteromalidae) has adapted an evasion strategy to avoid competition. Females of D. basalis show interspecific discrimination against hosts parasitized by Eupelmus vuilleti Crawford (Hymenoptera; Eupelmidae) and lay fewer eggs in the presence of females or hosts parasitized by the latter. Eupelmus vuilleti has adapted an aggressive strategy. In contrast to D. basalis, E. vuilleti concentrates her ovipositions on hosts already parasitized by D. basalis. Females of E. vuilleti preferably use oviposition holes made by other parasitoids, and are able to kill eggs and larvae of D. basalis selectively by thrusts of their ovipositor (ovicide and larvicide). Furthermore, E. vuilleti can act as a facultative hyperparasitoid on older larvae of D. basalis. The number of E. vuilleti offspring is not affected by the presence of D. basalis on a host. Our study does not provide insight in the process of larval competition.
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