Bruno Michel

Potential of threshold-based interventions for cotton pest control by small farmers in West Africa

Abstract Two types of threshold-based pest control schemes for cotton have been introduced by CIRAD, in collaboration with national research institutions in West Africa, to escape the traditional calendar-based spraying programme. In the first type (in Benin, Cameroon and Guinea), insecticides are still applied according to a calendar (5 or 6 sprayings at fortnightly intervals), but formulations and dosages depend on the pests observed on the day before spraying. In the second type (Faso, Mali, Senegal and Togo), insecticide is applied at a lower dosage than in the usual calendar-based programme and scouting is performed 6 days after spraying. Further spraying is performed on the next day if the threshold has been attained. Specific procedures depend on the country (sampling plan, insects considered as key-pests): spraying thresholds and active ingredients may vary according to these features. The main benefits of this approach are ecological and economic. A 40–50% reduction in pesticide consumption reduces the protection cost from US

Description of the sperm and spermatheca of Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) for the differentiation of mated and unmated females

50/ha to less than US

Procedures, advantages and constraints of staggered targeted control programmes on cotton in West Africa

30/ha. Accurate timing of spraying results in a 100–200xa0kg/ha increase in seed-cotton yield. Many constraints remain, the main one being the training of farmers in insect scouting and identification. They may account for the small acreage currently sprayed within the context of threshold-based pest control in cotton.

Manual de identificaçao das pragas e seus danos no algodoeiro

Abstract The coffee berry borer, Hypothenemus hampei (Ferrari), is a major insect pest of coffee crops worldwide. As part of a program of studies aimed at efficient and sustainable pest control, a study was conducted to determine the mating status of adult females in the broader context of studying pest dispersal behavior. To that end, it was deemed important to determine the morphology of the H. hampei female reproductive tract. This study focused on direct observation of the spermatheca of unmated, and colonizing adult females obtained from natural field populations with a high probability of having mated, and the description of all organs of the reproductive tract using established standard staining and microscopy techniques. Spermathecae were extracted from the samples and sorted according to their origin (unmated or colonizing females). The morphology of sperm present in the female spermathecae was compared with that of sperm taken directly from male testes. Two staining techniques using Giemsa and chlorazol black allowed spermatheca and sperm to be distinguished from other tissues. Under these conditions, a more precise description of the spermatheca was achieved, including the spermathecal duct and spermathecal muscles, spermathecal gland, and, for the first time, sperm when present. These techniques permitted the accurate and rapid determination of the presence or absence of sperm in the spermathecae of H. hampei females, thereby establishing their mating status.