Consequences of mixed species infestation on the searching behavior and parasitism success of a larval parasitoid

Abstract

When two herbivore pest species are potential hosts of a single parasitoid species, two questions arise. Firstly, which host is preferable for mass rearing in terms of later parasitoid performance, and secondly, how do parasitoids perform in mixed herbivore situations after colony establishment? We tested Hyssopus pallidus, a gregarious parasitoid of two major pests of apple, Cydia (Grapholita) molesta and Cydia pomonella, before and after landing on apples infested by one of the two Cydia species. Pre-alighting host preference was tested in a Y-tube olfactometer setup, and parasitism success in a contact bioassay. To gain information on parasitoid performance throughout the growing season, different fruit growth stages were used. Irrespective of the host they had developed on, the parasitoids showed similar olfactory preferences when given a dual choice between infested and healthy fruits, and they did not discriminate between fruits infested by C. molesta and C. pomonella. Responsiveness was generally high, especially late in the season close to harvest. Both hosts are parasitized regardless of the host the parasitoid female had developed on, and no differences in parasitism rates or number of offspring were noted for the two hosts offered. Results were consistent for all apple growth stages tested. In conclusion, mass rearing of this parasitoid can be carried out on either host, without limiting the future efficacy of the bio-control agent. Similarly, established colonies are expected to develop further on both hosts without any bias in host preference.

Predation by generalist predators on the codling moth versus a closely‐related emerging pest the oriental fruit moth: a molecular analysis

“…The present study concentrated upon ground‐active predators because their potential as biocontrol agents has been recognized in a broad range of agroecosystems (Symondson et al , 2002). To date, most studies of the regulation of the codling moth by natural enemies have focused on parasitoids (Mills, 2005; Hackermann et al , 2008; Jumean et al , 2009), nematodes (Navaneethan et al , 2010), birds (Solomon & Glen, 1979; Mols & Visser, 2002, 2007; Mols et al , 2005), carabid beetles (Hagley & Allen, 1988; Riddick & Mills, 1994; Epstein et al , 2001), earwigs and predatory bugs (Glen, 1977). To our knowledge, the only comparable work on regulation of the oriental fruit moth has focused on parasitoids (Hackermann et al , 2008; Poltronieri et al , 2008) and nematodes (Riga et al , 2006).…”