Behavioural plasticity in the stinging act of female ectoparasitoids

Abstract

The plasticity of the stinging behaviour of female Eupelmidae (Eupelmus vuilleti Crawford, E.orientalis Crawford Hymenoptera: Eupelmidae) was analysed through the interrelationships of a parasitic community living on larval stage of Callosobruchus maculatus Fabricius (Coleoptera: Bruchidae). In traditional African grainstores, Eupelmus females have at their disposal all the larval stages of their host. Their exploitation is revealed by the sting observed on the host caused by the ovipositor of parasitoid females. This stinging behaviour begins immediately on the adult female's emergence, and thereafter there is a daily increase in the number of hosts stung. Stinging activity is linked to the age of the available hosts, but not all of the hosts available are exploited by the two species studied. This absence of total exploitation could indicate a threshold of activity in the stinging acts which could be in part linked to the secretion activity of the poison glands of parasitoid female.In females of E.vuilleti and E.orientalis the stinging act is usually associated with egg-laying. The relationship between stinging and egg-laying is stronger in more advanced larval stages of the host.In the presence of parasitized hosts, females of E.orientalis and E.vuilleti can exhibit hyperparasitism. The majority of larvae (i.e. primary parasitoid) that have been hyperparasitized have been stung and a large number of them are completely inactive. However, E.vuilleti females deposited their eggs in the available space of the pupation chamber of the host. The neonatal larvae from these scattered eggs could exploit any available host without the female having 'prepared the ground' at the time of egg-laying.In Eupelmidae, all this happens as if there were a complementary action between the females and the neonate which could, if necessary, reinforce and/or compensate for the deficiencies in the host exploitation by the female.

Facultative Hyperparasitism: Extreme Survival Behaviour of the Primary Solitary Ectoparasitoid,Dinarmus basalis

“…To test this hypothesis that hosts can be rejected due to their immobility after the paralysing sting, the egg-laying behaviour of the ‘conditioned’ virgin females exposed to primary healthy and stung-paralysed C. maculatus hosts is examined. The same experimental method described above were used, since the C. maculatus stungparalysed L4 larvae hosts would be easy to identify due to their immobility and melanized scars ( Rojas-Rousse et al 1995 ).…”

An aphidiine parasitoid Monoctonia vesicarii (Hymenoptera: Braconidae) and three chalcidoid hyperparasitoids of Pemphigus matsumurai (Homoptera: Aphididae) forming leaf galls on Populus maximowiczii in Japan

“…Eupelmus vuilleti Crawford and E. orientalis Crawford can exhibit hyperparasitism, and the females deposit at least one egg on or near a parasitoid larva in the pupation chamber of the primary host bruchid Callosobruchus maculatus Fabricius. In this situation the neonatal larvae must locate and then reach the food target (Rojas‐Rousse et al . 1995).…”

Capacité de reproduction des femelles Eupelmus vuilleti (Eupelmidae), inséminées par des mâles développés en hyperparasitoïdes de Dinarmus basalis (Pteromalidae)

“…Dans un tel environnement, la compétition pour l'hôte conduit les femelles E. vuilleti à développer un comportement de cleptoparasitisme qui consiste à tuer les oeufs, les larves néonates et celles du premier stade larvaire du pteromalidae concurrent D. basalis [4,5]. Ce comportement permet à E. vuilleti de détourner au profit de sa descendance la nourriture représentée par l'hôte phytophage [4][5][6][7][8][9][10]. Chez les femelles E. vuilleti et E. orientalis, le cleptoparasitisme évolue jusqu'à l'hyperparasitisme du dernier stade larvaire de parasites en cours de développement [9,10].…”