Discrimination by Ganaspis pelleranoi of Ceratitis capitata larvae previously parasitised by Diachasmimorpha longicaudata

Abstract

Heterospecific and conspecific host discrimination, and super- and multiparasitism by the neotropical figitid Ganaspis pelleranoi were determined using 6-d-old Ceratitis capitata larvae in choice trials, where alternatives such as hosts previously parasitised by the exotic braconid Diachasmimorpha longicaudata, or by conspecific G. pelleranoi, and/or unparasitised hosts were available. Choice assays involved both experienced and naïve figitid females, previously host-exposed and non-host-exposed, respectively. Multiparasitism was mainly avoided if the G. pelleranoi female had a choice between unparasitised and parasitised larvae. Heterospecific host discrimination was highly improved by ovipositional experience. A very limited number of experienced G. pelleranoi females visited, probed, or oviposited host larvae previously parasitised by D. longicaudata. Only 2% of figitid adults were recovered from puparia resulting from larvae previously parasitised by D. longicaudata and exposed to naïve females. No figitid adults were recovered in those treatments involving experienced females. Latency and host examination data, number of visits, probing and oviposition’s activities showed that experienced G. pelleranoi female has a higher propensity to forage unparasitised host larvae rather than larvae previously parasitised by conspecific females. Self-superparasitism was greater than conspecific superparasitism when figited females had to choose between unparasitised and conspecific parasitised larvae. The ability of G. pelleranoi females to discriminate previously parasitised medfly larvae suggests low levels of both heterospecific and conspecific competition. Combined releases of D. longicaudata and G. pelleranoi in Argentinean fruit-growing regions could be a more advantageous alternative than individual species releases.