Sex Allocation Decision Under Superparasitism by the Parasitoid Wasp Eupelmus vuilleti

International audienceSuperparasitism is a widespread phenomenon in parasitoids and may be advantageous in some circumstances. In this study, offspring sex ratio was analysed in three superparasitism situations: when the second egg was laid by a random Eupelmus vuilleti (Hymenoptera: Eupelmidae) female from a group, when an isolated female was allowed to lay two eggs on the same host (self-superparasitism) or laid one egg on a host already parasitized by a conspecific (conspecific superparasitism). Females produced a different offspring sex ratio according to the different superparasitism situations tested. These sex ratios are in line with the local mate competition theory. The results further suggest that females can discriminate between hosts parasitized by a conspecific or by themselves and adapt the sex of the eggs they lay accordingly

Reproductive capacity of females Eupelmus vuilleti (Eupelmidae) inseminated by hyperparasitoid males developed upon the primary parasitoid Dinarmus basalis (Pteromalidae).

Eupelmus vuilleti is a primary and solitary ectoparasitoid of the larval stages of Bruchids (Callosobruchus maculatus, Bruchidius atrolineatus). In a context of intense competition for healthy hosts, E. vuilleti displays ovicide and larvicide behaviours towards the Pteromalid D. basalis during its development (kleptoparasitism), and in an extreme expression of kleptoparasitism the E. vuilleti females hyperparasitize the final larval stage (L5 stage) of D. basalis. In this study, we compared the variability of reproductive success in males that had developed in the context of hyperparasitism to that in males that had developed on primary hosts. The adaptation capacity of the males when 24 h old was analysed in terms of their weight, of the quantity of spermatozoids stored in the seminal vesicles, of the quality of insemination determined from the quantity of spermatozoids stored in the spermatheca of the females after the first mating, and of the number of daughters produced. Adults of E. vuilleti, the larvae of which had developed as hyperparasitoids, are smaller than those that have developed on primary hosts, but they keep all the abilities required to parasite a population of primary hosts once the competitive pressure is reduced

LES INSECTES BATISSEURS : Nids de termites, de guêpes et de frelons

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: Le connaître pour mieux le combattre

International audienceLe frelon asiatique Vespa velutina nigrithorax inquiète, interroge, voire même passionne. Venu de Chine, il pose des soucis en Europe : impacts négatifs sur les populations d’insectes, dont l’abeille, sur certaines activités économiques et sur la santé humaine. Face à ces divers problèmes, que pouvons-nous faire ? Quel(s) comportement(s) adopter en sa présence ? Des solutions existent-elles ? Ce livre propose donc, par des textes accessibles au plus grand nombre, et de multiples photographies spectaculaires, un état des lieux de nos connaissances sur ce frelon, des recherches menées sur celui-ci et sur les outils de lutte efficaces et sélectifs bientôt disponibles

Les termites, un monde de castes

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Les insectes sociaux (Editions Quae)

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Disentangling the role of active and human-mediated dispersal in the rapid spread of the invasive yellow-legged hornet, Vespa velutina

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R script for the potential spread of Vespa velutina in Europe. https://zenodo.org/record/1193663

https://zenodo.org/record/1193663R script to simulate the potential spread of the yellow-legged hornet in Europe (notably in some islands) and the data needed to do these simulations. This study was conducted in the frame of the project "FRELON" (2012-2014), which was supported by a French regional grant of Region Centre (France

Could hosts considered as low quality for egg-laying be considered as high quality for host-feeding?

International audienceWhen parasitoid females encounter a host, they can either lay an egg and thus invest in current reproduction or feed on the host and thus invest in future reproduction. However, hosts could have different values according to their parasitized status. Whereas already parasitized hosts represent poor quality for egg-laying, they could have a high nutritive value for feeding. Moreover, the optimal strategy adopted generally depends on the females' physiological state. In this study, the impact of the females' physiological state on their reproductive strategies was investigated in the solitary parasitoid Anisopteromalus calandrae.We analysed how their age and diet influenced (i) the use of hosts (feeding vs. oviposition) and (ii) host selection (previously parasitized vs. unparasitized). Our results show that both age and diet influence the reproductive strategy of A. calandrae females: old females fed with the poorer diet laid fewer eggs and made more host-feeding than others. Females also showed a preference for already parasitized hosts for feeding. This strategy cannot be explained by the nutritive value of haemolymph, as parasitized hosts carry fewer lipids. However, as parasitized hosts are also paralyzed, it could be less costly to feed on them than on unparasitized hosts