Toxic Effects of Groundnut Oil on the Rice Weevil Sitophilus Oryzae (L.)
On exposure of maize grains mixed with groundnut oil at a dose of 20 ml/kg, 100% mortality of the rice weevil, Sitophilus oryzae (L.) was observed within 24 hr and 100% at 10 and 5 ml/kg in 2 and 3 days.
Egg-laying and progeny development in the rice weevils were completely prevented at groundnut oil doses other than 1 ml/kg at which the number of eggs laid and progeny developed were 27 and 38% of those in the oil-free control during the same period. When maize treated with oil at 10–20 ml/kg was reinfested after 19 weeks with fresh adult rice weevils, less than 42% of them had died. The total number of progeny that emerged on week 23 from the two higher doses of oil was 38% of that emerging from the control.
Groudnut oil does not affect the viability of maize grains and damage after 25 weeks. Viability of maize grains was only 6–13% after oil treatment at 10–20 ml/kg compared to 100% in the untreated control.
Key WordsRice weevil Sitophilus oryzae groundnut oil toxic effects
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