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True bug (Heteroptera) impact on cocoa fruit mortality and productivity

Yédé, Babin R., Cilas C., Dibog L., Mahob R.J., Bilong C.F.B.. 2012. Journal of Economic Entomology, 105 (4) : p. 1285-1292.

The real impact of true bug damage on cocoa pods has never been assessed precisely. We conducted a 2-yr study on 1,080 cocoa trees on 36 farms in Cameroon to assess the contribution of true bugs to fruit mortality and production loss. The cocoa fruiting cycle, fruit mortality, and damage caused by true bugs as well as other pests and diseases were monitored on a weekly basis. True bug damage also was described on 2,500 ripe pods per year. Pod weight, bean number, and bean weight were measured and compared for different degrees and types of damage on the ripe pods. Our results showed that true bugs were the main external cause of young fruit abortion. They reduced the abundance of young fruit by up to 10%. In contrast, although one-third of the ripe pods sampled had true bug lesions, only 4% were moderately to heavily damaged. The mean weight of ripe pods was reduced by 12% when there was medium to heavy damage. While the mean weight of wet beans was reduced signiÞcantly (by 3Ð10%), the number of beans per pod was not changed by damage. Despite the reduction in mean weight, the overall weight of beans for the pods sampled was reduced by_2%. Therefore, our study conÞrmed thecommonassumption that the economic impact of true bug damage on mature pods is negligible on cocoa farms in Cameroon. However, true bugs have a signiÞcant impact on young fruit mortality. (Résumé d'auteur)

Mots-clés : développement biologique; flétrissement; dégât; miridae; fève de cacao; fruit; rendement des cultures; perte à la récolte; sahlbergella; theobroma cacao; cameroun; sahlbergella singularis; chérelle; cabosse

Thématique : Ravageurs des plantes; Troubles divers des plantes; Physiologie végétale : reproduction

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