Effect of temperature on the insecticidal potency of Acalypha godseffiana oil against Callosobruchus maculatus (F.)
2018
Olayinka Oni, Mercy | Ogungbite, Olaniyi Charles | Omotayo, Yusuff M.
The effect of temperature on the insecticidal potential of Acalypha godseffiana oil against the cowpea beetle Callosobruchus maculatus was tested in a laboratory. Oil was extracted from the leaves of the plant using ethanol as a solvent. The oil was divided into five portions; the first four portions were exposed to temperatures of 30, 40, 50 and 70°C, respectively, while the fifth portion (control) was only exposed to the laboratory ambient temperature of 28 ± 2°C. The oils were diluted into 2, 4 and 6% concentrations. Adult C. maculatus were exposed to the extracted oil at different concentrations with 3 replicates each. Phytochemical analysis of the oils was also performed. Mortality, oviposition, adult emergence, seed weight-loss and damage were observed. The control oil portion was associated with the highest insect mortality and the lowest oviposition, adult emergence, seed weight-loss and damage. Effectiveness of the oil decreased with increase in temperature. In addition, the quantity of the phytochemicals in the oil decreased with increase in temperature level. We conclude that under moderate temperature, the oil of this plant was effective in the control of the cowpea beetle, but under high temperature, it became ineffective.
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