ASSESSMENT OF THE IMPACT OF DIFFERENT DEVELOPMENTAL STAGES OF SAHLBERGELLAS INGULARIS HAGL. (HEMIPTERA: MIRIDAE) ON CACAO TREES PRODUCTIVITY AND FRUITS GROWTH UNDER FIELD CONDITIONS IN THE CENTRE REGION OF CAMEROON (CENTRAL AFRICA)

Abstract

Many studies have addressed the impact of mirids,particularlySahlbergellasingularisspecies on cocoa production in WestAfrica. However the effects of different developmental stagesof this insect on host plant remainunknown.This work aimed to evaluate the impact of the different stages of S. singularis on the productivity and growth of the fruits of Amelonado and Trinitariococoa varieties. We counted the number of feeding punctures on fruits as well ascherellesabortion, and measured the size of the surviving specimens then compared these with the control. The observations showed that all the development stages feed on cherelles. The number of feeding punctures upgraded from the larvae L1 stage to L5 irrespective to the cocoa variety, but Amelonado was more infested thanTrinitario. Within each cocoa variety, significant differencesin feeding punctures and aborted cherelles due toS. singularis developmental stages were observed. Trinitariowas relatively more susceptible than Amelonado to all developmental stages of S. singularis and recorded a higher number of abortedcherelles, values ranged from 58%for L1 to 100% for L5.Irrespective of the cocoa variety, these results showed thatolder mirid larval stages(L3, L4 and L5)significantly induced more damage on cocoa productivity, regarding cherelles abortion and size reduction of theinfected fruits. Overall, our findings showed that, compared toyounger larvae (L1 and L2),older ones and adults are more damaging for cocoa production and the economy this data should be incorporated in the IPM programs against S. singularis.