Abstract

Cucumeropsis mannii Naudin, (Cucurbitaceae) is cultivated in Africa for its important seeds used as food and in the traditional medicine. This work carried out in Yaoundé (Cameroon) focuses on the study of the entomofauna of C.mannii, on the impact of insects on plant yield; we studied also some aspects of the biology of Dacus bivitattus, main pest of this plant. Insect captured, breeding and identification were conducted from March to August 2001. The results permitted us to note that on C. mannii the entomofauna included 36 families. Within this fauna, there were various pests, predators, pollinators and nectarivorous. Among the 36 families recorded, 30 were collected on the leaves, 6 on the stems, 6 on the flowers and 2 on the fruits. The total number of fruits and their diameter were higher in unprotected plots than in protected one. The fruit ofC. mannii was a feeding and egg laying site for D. bivitattus. The total number of laying spots on a single fruit can reach the number of 20. Larval development took place inside the fruit; before pupation period, the last larval stage changed its coloration to milky white aspect and measured 9 to 10.5 mm in length. These larvae at this stage were mobile. The average time for pupation was 8.3 days. The youngest fruits were more attacked by flies than the older ones. These results constitute an important asset in the research of the protective strategy against natural pest of C. mannii.

Key words: Entomofauna, pests, Dacus bivitattus, yield, Cucumeropsis mannii,pollination.