Identification of compounds from the eggs of Ostrinia nubilalis and Mamestra brassicae having kairomone activity on Trichogramma brassicae

Abstract

In the presence of an extract of Ostrinia nubilalis or Mamestra brassicae eggs, female Trichogramma brassicae exhibited increased rates of upwind locomotion in the tubes of a linear olfactometer. GC and GC‐MS analyses of O. nubilalis and M. brassicae egg extracts revealed the presence of fatty acids, their ethyl esters, and various hydrocarbons. Exposing the wasps to a mixture of the five main saturated hydrocarbons (heneicosane, tricosane, pentacosane, heptacosane and nonacosane) increased the upwind progression in the olfactometer. Single hydrocarbons elicited reduced or no activity. Ethyl palmitate and palmitic acid were also effective in increasing upwind locomotion. Z11‐14: Ac, the main component of the female sex pheromone of O. nubilalis was inactive, regardless of its concentration. It is concluded that various compounds present on the surface of the O. nubilalis egg masses may play a role in the orientation of T. brassicae to its host. Résumé En présence d'un extrait superficiel d'oeufs d'Ostrinia nubilalis, ou de Mamestra brassicae, les femelles du parasitoïde Trichogramma brassicae présentent une tendance accrue à la remontée du tube dans un olfactomètre linéaire. L'analyse des extraits d'oeufs par chromatographie en phase gazeuse couplée à la spectrométrie de masse révèle la présence d'acides gras, de leurs esters éthyliques, et de divers hydrocarbures. Un mélange des principaux hydrocarbures saturés (hénéicosane, tricosane, pentacosane, heptacosane et nonacosane) déclenche également une remontée plus rapide et plus importante du tube. Chacun de ces hydrocarbures pris isolément présente une activité nulle ou réduite. D'autres constituants des extraits, l'acide palmitique et son ester éthylique, présentent également une certaine activité. En revanche, le Z11‐14: Ac, constituant majoritaire de la phéromone sexuelle d'O. nubilalis, est inactif, quelle que soit la dose utilisée. En conclusion, divers constituants présents à la surface des oeufs de la pyrale du maïs modifient le comportement locomoteur de femelles de T. maïdis et pourraient done jouer un rôle dans l'orientation de ce parasitoïde vers son hôte.

A survey of identified kairomones and synomones used by insect parasitoids to locate and accept their hosts

“…Several studies have shown that it is difficult to reconstitute mixtures that are as attractive as the original mixture (Turlings et al 1990b;Renou et al 1992). In many cases, several of the mixture's components may evoke strong reactions, but these reactions are not equal to the reaction to the natural mix (Elzen et al 1984;Turlings 1990b;Renou et al 1992).…”

Trichogramma Brassicae and SLAM®, an Integrated Approach to Managing European Corn Borer and Corn Rootworms

“…use egg mass kairomones as ques in locating eggs (Frenoy et al, 1992;Renou et al, 1992). One-to 2-d-old egg masses are preferred for oviposition compared with older egg masses (Renou et al, 1992). In treatment 3, ECB eggs were laid after the application of SLAM Ò .…”

Host Searching by Egg Parasitoids: Exploitation of Host Chemical Cues

“…Females responded most readily to a mixture of five synthetic saturated hydrocarbons, although when tested isolated, they had a very low response only to pentacosane. Females of T. brassicae were also found to be responsive to palmitic acid and ethyl palmitate, indicating that different compounds on the host egg may be used for host location (Renou et al 1992). Females of T. ostriniae were shown to respond to accessory glands from mated females besides the extracts and egg masses of the host Ostrinia furnacalis (Guenée) (Bai et al 2004;Yong et al 2007).…”