Influence of herbivorous insects on the production of Lagenaria siceraria (Molina) Standley (Cucurbitaceae)

The production of indigenous cucurbits remains very low in tropical zones, mainly due to herbivorous insect damage. This study was conducted in Manfla located in the centre of Cote d’Ivoire at 400 km from Abidjan to evaluate the impact of herbivorous insects on foliar damage and agronomic parameters of Lagenaria siceraria (Molina) Standley (Cucurbitaceae). Our study revealed that nine insect species belonging to four families and three orders were responsible for foliar damage. The leaves were perforated, shredded and eaten away. The extent of foliar damage was estimated for each accession during three consecutive cropping seasons. For the oleaginous gourd accessions NI227, NI219 and NI180, over 75% of the leaf surface was regularly destroyed. For the bottle gourd accessions NI431 and NI432 and the oleaginous gourd accession NI354, leaf surface damage was less than 25%. Thirteen accessions were intermediate between the two groups of accessions cited above. There was no significant difference between fruits weight and seed weight for accessions NI431, NI432, NI354 and NI434, whether or not plants were treated with a broad spectrum cypermethrin based-insecticide (Cypercal 50 EC). However, these parameters differed significantly for accessions NI227, NI219 and NI180.   Key words: Herbivorous insect damage, agronomic parameters, damage on foliar surface, extent of foliar damage.