Biologie, éco-éthologieet dynamique des populations du scolyte des grains de café, Hypothenemus hampei Ferr. (Coleoptera, scolytidae), en Nouvelle-Calédonie / Philippe Giordanengo.

Tese (doutor) - Universite de Rennes 1 1992

Hypothenemus hampei Ferr. (Coleoptera, Scolytidae), a strictly monophagous seed eater, is the major pest of coffee farming in New Caledonia. Mating which takes pIace into the emergence seed is faciIitated by the intervention of signals, probabIy of olfactive nature, emitted by the females. About twelve days from their emergence, females leave their hatching berry c10se of the inversion of their phototropic and thigmotactic behavior. The dispersal which is generally made by flight, is the only period of their life cyc1e during which beetles are outside coffee seeds. During the colonization flight, females are guided in their search by volatile compounds (kairomones) emitted by the berries. The males which are unable to fly and to pierce seed husks da not directIy take part in the colanies extend. At the beginning of the fructification cycle, at the time of the setting up of the ncw calonies, the only criterion of trophic availability is at the origin of the spatiotemporal distribution of the infestations. Then, the ability of the colonizing females to select ripe berries, the probable intervention of aggregative pheromones and the reduced extent of the flights due to the abundance of fruits favour the roundup of the populations on certain coffee trees. It's the same within these trees where colonies are distributed in aggregate form. Microclimatic conditions induced by the vegetable cover are partIy responsible for the reduction of the expansion ability of the phytophagous. The lenghtening of the development cycle and the important mortality of eggs and larvae are at the origin of the contrast between the seasonal gradation of the beetle populations in the traditional coffee plantations and the observable swarms in the open plantations. These works lead to suggestions regarding the development of integrated methods of monitoring this pest and some farming recommendations which appear urgent to implement in view af a so deteriorate situation.