MORTALITY OF MAIZE PESTS (SITOPHILUS ZEAMAIZE) AND BEAN PESTS (COLOSOBROCUS MACULATUS) EXPOSED TO EXTRACTS OF NEEM (AZADIRACHTA INDICA) BARK, ROOT AND ONION BULB.
This study was carried out to evaluate Mortality of maize pests (sitophilus zeamaize) and bean pests (colosobrocus maculatus) exposed to extracts of neem (azadirachta indica) bark, root and onion bulb against. S. zeamais and C. maculatus were cultured and maintained at a temperature of 26-27°C and relative humidity of 65-70%. There were fourteen (14) treatments in the first experiment which was replicated three times and arranged in completely randomized design (CRD). Mortality of Pest, Number of holes/ punctures and Weight loss were assayed for four weeks. The results showed that at 4 weeks of treatment, there was a significant difference (P>0.005) between the neem onion bulb powder, neem leaf and bark treatments and the control. The highest mortality rate was recorded in neem bark powder (3.59%) followed by the neem root powder (2.71%). During 8 weeks of the experiment, neem bark powder recorded the highest mean mortality (10.8%) against C. maculatus and C. zeamais. Followed by neem root powder (8.33%) while the biopesticidal effects was recorded from onion bulb powder (3.22%); Similarly, at 12 weeks, neem bark powder had the highest mortality against the weevils with a value of 26.2% followed by the neem root powder (10.7%) while the control treatment recorded no mortality against the weevils. At 20 and 24 weeks of the experiment, there was a marked increase in mortality rates for both weevils used for the study. The 50% lethal dosage of neem leaf powder, neem bark powder and onion bulb powder on mortality of insect species of maize and bean were: Neem bark powder (100g) 1.94(1.49-2.00); Neem root powder (100g) 2.73(2.68-2.84); and Onion bulb powder (100g) 3.27(3.12-3.40) respectively. The study revealed that some of the plant materials (onion bulb) despite not giving very high mortality of Sitophilus zeamais and Colosobrocus maculatus, were effective in performance than the untreated control.
Keywords: mortality, maize pests (Sitophilus zeamaize), bean pests (Colosobrocus maculatus) neem (Azadirachta indica) bark, root, and onion bulb.
