Rôle de l'intensité lumineuse sur les capacités parasitaires d'Eupelmus orientalis Crawford et d'Eupelmus vuilleti Crawford, parasitoïdes des Bruchidae ravageurs de graines de niébé (Vigna unguiculata Walp.)

Biotechnologie, Agronomie, Société et Environnement

关键词: Bruchidae;    Bruchidae;    Cowpea;    escape;    Eupelmus orientalis;    Eupelmus orientalis;    Eupelmus vuilleti;    Eupelmus vuilleti;    light intensity;    parasitoids;    storage systems;   

DOI  :  

来源: DOAJ

【 摘 要 】

Role of light intensity on parasitic capacities of Eupelmus orientalis Crawford and Eupelmus vuilleti Crawford, parasitoids of Bruchidae pests of cowpea (Vigna unguiculata Walp.) seeds. In tropical Africa, Callosobruchus maculatus Fabricius is a cowpea pest. After the harvest, the disappearance of one of C. maculatus parasitoids (Eupelmus orientalis Crawford) limits the duration of stocks conservation. In this study, we used an experimental model imitating the traditional african granaries taking into account the lack of airtightness and the variability of the internal luminous intensity of the different types of granaries. Three kinds of cages were used: cages with an internal luminous intensity of 380 lux, cages with an internal luminous intensity of 3.5 lux, and some others with an internal luminous intensity of 0.2 lux. Four little holes are pierced on the sides of each cage. Each hole was provided with a trap to catch the insects that escaped. Inside each cage, 20 E. orientalis and Eupelmus vuilleti Crawford nymphs were placed. In adult stage, the insects faced a choice of either to escape, or to stay in the cage and then parasitize available hosts. The trapped individuals as well as those remaining in the cage are sorted out by species. Available hosts in the cage which had parasites are also sorted out. The results show that the E. orientalis females born in the cage hardly parasitize available hosts and escape in majority compared to E. vuilleti which stay in the cages. In 380 lux cages, 19% of E. orientalis females escape compared to 6% of E. vuilleti. This percentage of evasion increases with the darkning of the enclosure. Thus, 62% of E. vuilleti females escape from the cages of 3.5 lux and only 11% escape from the cages of 0.2 lux. The majority of E. orientalis individuals escape right from birth, which therefore explains their disappearance from storage. This escape behaviour constitutes a factor limiting the use of this parasitoid as a biological control agent against bruchids.

【 授权许可】

Unknown