Investigations on the potentials of Tithonia diversifolia and Tithonia rotundifolia as biological control measures of cowpea weevil (Callosobruchus maculatus)

A laboratory study was carried out in the Laboratory of the Department of Plant Science of Ekiti State University, Ado Ekiti to investigate the potentials of Tithonia diversifolia (Helms) A. Gray and Tithonia rotundifolia (Mill.) S.F. Blake as biological control measures of Cowpea weevil (Callosobruchus maculatus). Collected plants were cleaned, air-dried for four weeks and powdered. The powder materials were extracted using ethanol, cold water, or hot water. An aliquot of 0.1,0.2,0.3 and OAml of either T. diversifolia or T. rotundifolia was pipette into Petri dishes containing 20g of disinfested cowpea grains, thoroughly mixed and air dried for two hours before 20 adult weevils were introduced. Weevil's mortality was observed daily for 96h. The highest mortality of cowpea weevil was observed in the ethanol extract of both the T. diversifolia and T. rotundifolia at OAml after 96h. Cold water extract gave lower cowpea weevil mortality than the hot water extract. Ethanol was observed to have increased the potency of the plant extracts used. It is concluded that either T. diversifolia or T. rotundifolia can be used as bio-insecticide to control cowpea weevil in stored cowpea seeds.