Oni, M. O

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Contact and fumigant bioassay of Terpinolene compound was conducted at five concentration levels of 0.2, 0.4, 0.6, 0.8 and 1.0ml /20 g wheat grains against Rhyzopertha dominica. Parameters assessed were adult mortality at 24, 48, 72 and 96 hours of exposure, adult emergence, percentage inhibition rate and grain weight loss due to infestation by R. dominica. Significantly (P < 0.05), direct toxicity was observed on the insects compared to negative control with 100% mortality at 72 and 96 h at 0.8 and 1.0 ml/20 g grains respectively. Percentage mortality was dosage and exposure time dependent. LD50 of 3.75 and 4.17ml of terpinolene evoked 50% adult mortality. Adult emergence and percentage weight loss decreased with increased dosages, while percentage inhibition rate increased with increased treatment dosages. It was concluded that, Terpinolene compound proved effective biopreservative for the control of R. dominica infesting stored wheat grains suggesting future evaluation of mode of action for crop protection commercialisation.