Insecticidal efficacy of abamectin against three stored-product insect pests: influence of dose rate, temperature, commodity, and exposure interval.

The insecticidal efficacy of abamectin against adults of Rhyzopertha dominica (F.), Sitophilus oryzae (L.), and Tribolium confusum Jacquelin du Val was assessed under laboratory conditions. The efficacy of abamectin was assessed on two commodities (wheat, Triticum aestivum L. and maize, Zea mays L.) and two temperatures (25 and 30 degrees C). The dose rates used were 0.01, 0.1, 0.5, and 1 ppm. Mortality of the exposed adults in the treated grains was measured after 7, 14 and 21 d (= days), whereas progeny production was assessed 60 d later. Increase of dose rate, exposure interval, and temperature enhanced the efficacy of abamectin. Noticeable mortality was noted for all species after 21 d of exposure, although for S. oryzae, mortality was very high even at 7 d. For dose rates higher than 0.5 ppm, the efficacy of abamectin was higher in maize than in wheat against all species tested. Finally, progeny production was measured for all three species on commodities treated with 0.01 and 0.1 ppm of abamectin.