Study mission in Indonesia for improvement of Oryctes rhinoceros trapping (27/11 to 18/12/1998) : EU-INCO Project N° IC18CT970199

Oryctes rhinoceros trapping is already possible with the synthetic pheromone ethyl 4-methyloctanoate as the attractant. A trial is under way to determine the optimum dose with the trap currently used at Marihat. The role of this pheromone (when and how it intervenes in the life of the insect) is unknown. It needs to be determined, so that trapping efficacy can be improved. An inspection of young palms showed that there is no aggregation on young palms and that they are colonized as much by males as females. In old stems, initial observations did not reveal under what conditions the insects frequented such materials to reproduce. Observations need to be continued under better conditions and, in particular, they need to cover sites that have not been examined in the past. Old, dead palms left standing, if possible, would enable highly instructive examinations. The trial designed to study any synergy between the pheromone and compost has been rendered unexploitable by the theft of several traps. However, in two complete replicates, captures were greater (2.5 times) in traps containing both pheromone and compost. That result needs to be checked in another trial, in which steps are taken to prevent thefts. A long-duration trial has been set up to determine the stage and age of empty bunches that are most attractive, so that studies can be undertaken to identify volatile compounds and any synergy with the pheromone. At the same time as these field studies, laboratory tests were carried out. Olfactometry using a two-choice pitfall olfactometer can provide useful information for achieving the objectives of this work. The first tests have been encouraging. They should be continued in accordance with the proposed programme. The studies carried out on O. rhinoceros require close collaboration between IOPRI partners in the field, and CIRAD and INRA partners at the INRA chemical mediators laboratory in Versailles. It is essential to strengthen it by a more frequent exchange of correspondence, in order to overcome the problems encountered in the field more rapidly and benefit mutually from each other's experience. (Résumé d'auteur)