Joint action of spinetoram and clove powder mixture against the rice weevil, Sitophilus oryzae (L.)

To ascertain the combined effect of spinetoram and clove powder in contrast to the Sitophilus oryzae adults (Coleoptera, Curculionidae), bioassay tests were executed, at 65 ±5% relative humidity and 28 ±2°C for a duration of 21 days. The examinations were conducted at various concentrations: six for spinetoram, five for clove powder, and two regarding their blends. In addition, the repellent activity of the examined substances, both individually and in combination, was evaluated. The findings showed that as the concentration increased, so did the tested insect's mortality rate and the duration of exposure. Information showed that, the spinetoram was extremely harmful to the insect being treated, LC50 for S. oryzae adults was 7.7×10-4 % (w/w) after a seven-day exposure period. Information also revealed that, LC50 of clove powder was 4.5% (w/w) at the same exposure period. The two examined substances' combined effectiveness at the employed doses showed that Mixture B (spinetoram at LC50 + clove powder at LC20) was more effective compared with Mixture A (spinetoram at LC20 + clove powder at LC50) in opposition to S. oryzae due to co-toxicity factor and the time to reach the complete mortality of tested insect. Repellent activity varied with concentration and exposure time, generally decreasing over time. Mixture A was most effective, followed by clove powder at LC50.