OVIPOSITION BEHAVIOUR AND POD MARKING IN THE CABBAGE SEED WEEVIL, CEUTORHYNCHUS ASSIMILIS

Abstract

Behavioural events underlying observations of uniform egg dispersion in field populations of the cabbage seed weevil, Ceutorhynchus assimilis, among winter rape, Brassica napus, seed pods (siliques) were investigated. We observed that each act of egg deposition into a pod was followed by specific and fixed behaviour in which females brushed the pod surface with a brush‐like structure on the ovipositor. Evidence is provided that chemical marking of the pod surface occurs during brushing, resulting in deterrence of repeated oviposition into the same pod. Ecological implications of pod marking by cabbage seed weevils as well as similarities with the corresponding behaviour of various host marking insects are discussed. RÉSUMÉ Comportement de ponte et marquage des siliques par Ceutorhynchus assimilis L'examen a porté sur les traits comportementaux responsables de l'observation dans la nature d'une distribution uniforme des œufs de Ceutorhynchus assimilis dans les siliques de Brassica napus. Nous avons observé qu'après chaque acte de dépôt d'œufs dans une silique succède un comportement spécifique et fixé pendant lequel la femelle brosse la surface de la silique avec une structure en brosse de l'ovipositeur. Nous avons pu démontrer que pendant ce brossage, la surface de la silique est marquée chimiquement, ce qui dissuade toute ponte répétée dans la même silique. La discussion porte sur les conséquences écologiques du marquage des siliques par C. assimilis et sur les analogies avec les différents comportements de marquage d'hôtes chez les insectes.

Gorse pod susceptibility and oviposition preference to the gorse seed weevil,Apion ulicis(Forster) (Coleoptera: Apionidae)

“…This would lead to a uniformity in egg dispersion among susceptible pods in the field, thereby reducing the number of occasions on which there is a deleterious effect on fitness caused by larval competition (Prokopy et al 1984). This is seen in several of the Curculionoidea: the bean weevil, Callosobruchus maculatus (Mitchell 1975;Messina & Renwick 1985;Wilson 1988), the dry bean weevil, Acanthoscelides obtectus (Szentesi 1981), the boll weevil, Anthonomus grandis grandis (McKibben et al 1982), and the cabbage seed weevil, Ceuto"hynchus assimi.lis (Kozlowski et al 1983). In these weevils, this effect is mediated by substances termed epideictic pheromones.…”

“…They are chemical markers that deter conspecific females from laying eggs into the same substrate provided alternative egg laying sites are available (Szentesi 1981 ). These pheromones may be deposited during egglaying (Kozlowski et al 1983), defecation, or adult walking (Messina & Renwick 1985). It is not known whether epideictic pheromones are used by Apion ulicis.…”

Resistance of canola-quality cultivars of yellow mustard, Sinapis alba L., to the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham)

“…Feeding punctures are made before oviposition (Kozlowski et al 1983) and a reduction in feeding punctures may indicate reduced acceptability. However, not all feeding punctures produced by a female contain an egg, even in a susceptible host (Dmoch 1965).…”

Laboratory and Field Observations of the Behavior of Eustenopus villosus while Feeding and Ovipositing on Yellow Starthistle

“…The excrement on the capitulum could be a deterrent (Kozlowski, 1983), but the three females that were individually placed on a capitulum immediately following oviposition by another weevil were not deterred from using the capitulum. Furthermore, the new weevils spent over 2 h each feeding in the previously used oviposition cavity before laying their own egg within it.…”

“…It may have been marking the capitulum with an oviposition deterring pheromone (Prokopy 1981;Kozlowski et al, 1983). We conducted preliminary studies to assess the presence of a marking pheromone by placing one male and three female weevils individually on capitula immediately after a previous weevil fed and oviposited to see if they would be deterred from the capitulum.…”