Entomofaune associée à la culture de cucurbites oléagineuses africaines (Lagenaria siceraria Molina (Standl. 1930) et Citrullus lanatus Thumb (Matsum & Nakai 1916)) et impact des ravageurs sur la production

The fruit production of African oleaginous cucurbit plants is severely limited by insect pests. Here we conducted an inventory of the entomofauna associated with Lagenaria siceraria Molina (Standl.) and Citrullus lanatus Thumb (Matsum & Nakai), two African cucurbites, in parallel to assessing the damage that insect pests cause to these plants and their impact on fruit yield. We subsequently conducted randomized experiments on treated and control plots of 49m2 of area. Plots were treated with CYPERCAL 50 EC (50 g/l of Cypermetrin) and FURADAN 5G (50 g/kg of Carbofuran). Insects collected from plots were identified and counted. We also assessed the attack rate on plants and fruit yield (number and weight of fruit and seedlings). Seventy-one species belonging to 41 families from 10 insect orders were identified (Coleoptera, Hymenoptera, Diptera, Lepidoptera, Orthoptera, Homoptera, Heteroptera, Dictyoptera, Odonata and Dermaptera). The main pests on cucurbit plants were Chrysomelidae (Lamprocopa occidentalis, Aulacophora foveicolis, Aulacophora africana, Asbecesta cyanipennis, Ootheca mutabilis and Lilioceris livida), Coccinellidae (Henosepilachna elaterii and Henosepilachna reticulata) and Meloidae (Mylabris holosericea). Fifty percent of plants were healthy on treated plots versus 0-33% on control. The number of fruits on treated plots (37.16 ± 2.99 for L. siceraria and 42.33 ± 2.58 for C. lanatus) were significantly (P < 0,001) higher compared to control (29.33 ± 4.67 for L. siceraria and 31.33 ± 3.5 for C. lanatus). The yield on treated plots (222.39 ± 15.78 kg/ha for L. siceraria and 127.4 ± 8.16 kg/ha for C. lanatus) were significantly (P < 0,001) higher compared to control (144.4 ± 14.52 kg/ha for L. siceraria and 88.18 ± 8.09 kg/ha for C. lanatus). In conclusion, this study demonstrated that by reducing pest populations and damages, insecticide treatments improved cucurbit production more than 40%. © 2015 Société entomologique de France.