Laboratory bioassays were conducted to evaluate the insecticidal effect of diatomaceous earth （DE）, SilicoSec against Callosobruchus maculatus （F.）, Rhyzopertha dominica （F.）, Sitophilus zeamais （Motschulsky）,...Laboratory bioassays were conducted to evaluate the insecticidal effect of diatomaceous earth （DE）, SilicoSec against Callosobruchus maculatus （F.）, Rhyzopertha dominica （F.）, Sitophilus zeamais （Motschulsky）, and Tribolium castaneum （Herbst） in cowpea, maize and wheat, at 25-32 ℃ and 54-68% relative humidity （r.h.）. SilicoSec was applied at rates： 0 （untreated control） 250, 500, 750 and 1,000 mg/kg of commodity. Adult mortality was measured after 3 to14 days of exposure. Progeny production was assessed after 40 or 56 days. The tested species varied in sensitivity to SilicoSec, with S. zeamais being most susceptible, but no significant differences in mortality levels observed between R. dominica, C. maculatus or T, castaneum after three days of exposure. After 5 days of exposure, all C. maculates adults died on cowpea treated at 1,000 mg/kg. Similarly, after 14 days of exposure all adults of the other species died on grains treated at 1,000 mg/kg, and were ranked in decreasing order of susceptibility S. zeamais 〉T castaneurn 〉 R. dominica. SilicoSec treatments suppressed progeny production （30 to 100%） in all the tested species. The implications of these findings to DE-based control strategy are discussed.展开更多
A wide range of insect pests attacks stored sorghum grains and the significant damage in grain weight loss and negative impact on the nutritional values of sorghum are caused with the activities of these pests. The in...A wide range of insect pests attacks stored sorghum grains and the significant damage in grain weight loss and negative impact on the nutritional values of sorghum are caused with the activities of these pests. The insecticides, especially from organophosphate group （OP）, are still used to prevent damage of sorghum grains during storage period. One of the possible replacements for OP and other synthetic insecticides is a natural and safe diatomaceous earth （DE）. The primary objectives of this study was conducting the laboratory experiments with enhanced DE Protect-lt on Sitophilus oryzae （L.）, Rhyzopertha dominica （Fab.） and Tribolium castaneum （Herbst.） to find out the effective concentrations and to determine the effect of applicable concentration of DE on bulk density （test weight） of sorghum grains. The effect of Protect-it on bulk density was measured at 1,000 ppm. After the exposure of S. oryzae, R. dominica and T castaneum to treated grains during 13 days, lethal dosis that causes 90% mortality （LD90） were 811 ppm, 1,102 ppm and 1,244 ppm, respectively. After exposure of 8 days the concentration of 1,000 ppm generated the mortality ofS. oryzae 100% and for R. dominica and T.castaneum for over 99%. The same concentration had a minimal effect on the reduction of sorghum bulk density （for 1.95% only）.展开更多
文摘Laboratory bioassays were conducted to evaluate the insecticidal effect of diatomaceous earth （DE）, SilicoSec against Callosobruchus maculatus （F.）, Rhyzopertha dominica （F.）, Sitophilus zeamais （Motschulsky）, and Tribolium castaneum （Herbst） in cowpea, maize and wheat, at 25-32 ℃ and 54-68% relative humidity （r.h.）. SilicoSec was applied at rates： 0 （untreated control） 250, 500, 750 and 1,000 mg/kg of commodity. Adult mortality was measured after 3 to14 days of exposure. Progeny production was assessed after 40 or 56 days. The tested species varied in sensitivity to SilicoSec, with S. zeamais being most susceptible, but no significant differences in mortality levels observed between R. dominica, C. maculatus or T, castaneum after three days of exposure. After 5 days of exposure, all C. maculates adults died on cowpea treated at 1,000 mg/kg. Similarly, after 14 days of exposure all adults of the other species died on grains treated at 1,000 mg/kg, and were ranked in decreasing order of susceptibility S. zeamais 〉T castaneurn 〉 R. dominica. SilicoSec treatments suppressed progeny production （30 to 100%） in all the tested species. The implications of these findings to DE-based control strategy are discussed.
文摘A wide range of insect pests attacks stored sorghum grains and the significant damage in grain weight loss and negative impact on the nutritional values of sorghum are caused with the activities of these pests. The insecticides, especially from organophosphate group （OP）, are still used to prevent damage of sorghum grains during storage period. One of the possible replacements for OP and other synthetic insecticides is a natural and safe diatomaceous earth （DE）. The primary objectives of this study was conducting the laboratory experiments with enhanced DE Protect-lt on Sitophilus oryzae （L.）, Rhyzopertha dominica （Fab.） and Tribolium castaneum （Herbst.） to find out the effective concentrations and to determine the effect of applicable concentration of DE on bulk density （test weight） of sorghum grains. The effect of Protect-it on bulk density was measured at 1,000 ppm. After the exposure of S. oryzae, R. dominica and T castaneum to treated grains during 13 days, lethal dosis that causes 90% mortality （LD90） were 811 ppm, 1,102 ppm and 1,244 ppm, respectively. After exposure of 8 days the concentration of 1,000 ppm generated the mortality ofS. oryzae 100% and for R. dominica and T.castaneum for over 99%. The same concentration had a minimal effect on the reduction of sorghum bulk density （for 1.95% only）.
