Réponses électroantennographiques de deux parasitoïdes Ichneumonidés, Diadromus pulchellus et D. collaris, aux odeurs de végétaux, du phytophage‐hôte Acrolepiopsis assectella et du partenaire sexuel

Abstract

Chez Diadromus pulchellus WSM et D. collaris Gr., Hyménoptères Ichneumonidés parasitoïdes spécialistes des nymphes d'A. assectella lépidoptère inféodé aux Allium, des EAG sont enregistrés en réponse à l'odeur du poireau sain ou attaqué par les larves du phytophage, odeurs actives par ailleurs sur leur comportement locomoteur (cinèses). Le thiosulfinate de dipropyle (Ti‐P2) très spécifique et abondant dans les Allium, et instable, est le mieux perçu par les deux parasitoïdes mais n'a aucun effet locomoteur chez D. pulchellus contrairement aux disulfures et thiosulfonates, plus stables et moins spécifiques. Les propriétés de l'acétate d'éthyle, actif sur l'antenne des deux parasitoïdes, et sur la locomotion de D. pulchellus expliqueraient en partie les activités biologiques du poireau attaqué sur ces parasitoïdes. Des EAG sont aussi obtenus chez les deux espèces avec l'odeur du chou et de composés soufrés plus ou moins spécifiques des Crucifères. Le thiocyanate de méthyle (TCN‐M), le plus actif sur l'antenne et seul efficace sur le comportement locomoteur (de D. pulchellus), expliquerait en partie l'installation reconnue de D. collaris sur Plutella maculipennis spécialiste des Crucifères et rend celle de D. pulchelles vraisemblable. L'odeur des larves de dernier stade d'A assectella est seule efficace sur l'antenne et la locomotion des femelles de D. pulchellus. Les mâles de ce dernier réagissent (EAG, locomotion) à des odeurs de cocons de l'hôte et particulièrement à ceux occupés par une femelle de leur espèce. Summary EAG responses of two ichneumonid parasitoids, Diadromus pulchellus and D. collaris, to odours emitted by plants, the phytophagous‐host Acrolepiopsis assectella and the sexual partner Diadromus pulchellus WSM and D. collaris Gr., Hymenoptera Ichneumonidae, are parasitoids of nymphs of A. assectella, Lepidoptera which is a specific feeder on Allium spp. The parasitoid's EAG responses to healthy leek plant odours and to that of plants attacked by A. assectella were recorded. These host‐plant odours are also influenced the parasitoids' locomotor behaviour (kineses). Propyl propane thiosulfinate (Ti‐P2) which is very specific and abundant in Allium, and unstable, was best perceived by the two parasitoids. Unlike the more stable and less specific disulphurs and thiosulphonates it had, however no effect on the locomotor activity of D. pulchellus. The properties of ethyl acetate, which induced strong EAG responses in both parasitoids and influenced D. pulchellus locomotor activity, could partly explain the attacked plant's biological activity. EAG responses were also recorded for both species to cabbage odour and to more Crucifer‐specific sulphur compounds. EAG responses to methyl thiocyanate (TCN‐M) was the best for the two parasitoids. The locomotor activity of D. pulchellus was only affected by this compound and the Crucifer specialist Plutella maculipennis is attacked by D. collaris. Moreover, this phytophage's colonisation by D. pulchellus is also plausible in the light of this evidence. The r...

Response of Trichogramma chilonis to infochemicals: an SEM and electrophysiological investigation

“…Males of the parasitoid Diadromus pulchellus Wesmeal and D. collaris Gravenhorst are known to perceive plant volatiles (Leconte and Pouzat, 1985). The scale extracts at 1 ae/ml elicited higher responses than the leaf extracts at 10 gle/ml and even certain chemicals such as b-myrcene, S-()) limonene and b-pinene in females, besides a-pinene in males, which are part of the complex blend of chemicals released in cotton after herbivore damage.…”

Antennal Electrophysiological Responses of Three Parasitic Wasps to Caterpillar-Induced Volatiles from Maize (Zea mays mays), Cotton (Gossypium herbaceum), and Cowpea (Vigna unguiculata)

“…So far, no data are available on the perception of induced odor by C. marginiventris and M. rufiventris. EAG recordings have also been used to test the sensitivity of antennal perception in some other parasitoids (Lecomte and Pouzat, 1985;Salom et al, 1991;Jyothi et al, 2002). Only a few studies on parasitoids have been done using coupled GC and EAG systems.…”

Electrophysiological investigations of sex pheromone reception and release in Bruchidius atrolineatus

“…No EAG was recorded with the antenna of a female stimulated by the odour of twenty males or twenty females. This was not due to the inability of the antennal receptors of the female to respond to odours: typical EAGs (Kaissling, 1971;Lecomte & Pouzat, 1985;Light ef al., 1988) were recorded with amyl acetate vapours. The same observations were made with male antennae stimulated by the odour of twenty males.…”

“…1957;Pouzat, and insemination. 1974;Lecomte &Pouzat, 1985, except for the following details. The antenna was not separated from the head, and the whole insect was maintained in plasticine after amputating its legs.…”