Population density of insect pests associated with watermelon (Citrullus lanatus Thumb) in southern guinea savanna zone, Ogbomoso

Identification and determination of insect pests are key components of integrated pest management. This experiment was conducted at Teaching and Research farm, Ladoke Akintola University of Technology (LAUTECH) during early and late planting seasons of 2011 and 2012. The experiment was arranged and demarcated in a randomized complete block design.Eight insects were observed – Phyllotreta cruciferae, Monolepta spp, Zonocerus variegatus, Aulacophora africana, Diabrotica undecimpunctata, Dacus cucurbitae, Copa occidentalis, and Coccinella septempunctata. The studied insects attacked mostly the leaves except D. cucurbitae. D. cucurbitae had highest infestation at flowering and fruiting stages in both planting seasons whereas 52.8% infestation was recorded by P. cruciferae at seedling stage in the early season but D. undecimpunctata had highest population density (50.1%) during the late planting season. Infestation by the observed insects commenced two weeks after planting and peak activity was at 7 week after planting. Therefore, management of these insects should be initiated two weeks after planting