Field evaluation of two aqueous plant extracts on water melon Citrullus lanatus (Thumb) insect pests in Northern Guinea savannah of Nigeria

Leaf beetles and fruitfly infestation greatly limits water melon (Citrullus lanatus) production throughout the tropics. The efficacy of aqueous plant extracts applied at 5 % w/v concentration of two botanicals (neems seed oil and garlic bulb) and 1.5 melt of one synthetic insecticide (karate 2.5 EC) against their infestation were evaluated. The effects of these treatments including control on the number of the insects, number of leaves, vines, length of vines, number of fruits, fruit weight, fruit damaged and undamaged were assessed during 2012 and 2013 cropping seasons in Lawanti, Gombe state, Northern Guinea Savannah region of Nigeria. Result of the study showed that neem seed oil and garlic bulb treatments at 5 % w/v were effective against the leaf beetles and water melon fruitfly as the synthetic insecticide karate 2.5 EC in managing the water melon insect pests. Karate 2.5 EC significantly reduced the infestation of the insect pests of water melon and increased number of leaves, vines, length of vines, number of fruits, fruit weight and number of undamaged fruits/plot followed closely by neem seed oil (A. indica) and garlic bulb (A. sativum) extracts. Water melon a growth and fruit yields were appreciably improved in these treatment while untreated control water melon crops had more leafs beetles and fruitfly infestations, poor plant growth and lower fruit yields. Both botanicals can thus serve as alternatives to synthetic insecticides for managing water melon leaf beetles and fruitfly attack.