Efficacy of Silicosec, a diatomaceous earth formulation against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae).

Laboratory bioassays were carried out to evaluate the insecticidal efficacy of SilicoSec against 7- 14-days-old adults of Tribolium castaneum; old and young larvae with the mean weight of 3.4 +/- 0.1 and 0.6 +/- 0.1 mg, respectively at 27 degrees C and 55 +/- 5% r.h in the dark. Wheat treated with four dose rates of SilicoSec with three replications. Adult's mortality was measured after 2, 7 and 14 days of exposure. After 14 days mortality count, all adults were removed and samples retained under the same conditions for a further 60 days to assess progeny production. In the case of larvae, mortality was counted after 1, 2 and 7 days. After 2 days of exposure no concentration achieved 11% mortality for adults, however; adult's mortality exceeds 89.65% when exposed for 7 days to SilicoSec. Mortality of old and young larvae at 0.6 g kg(-1) after 2 days were 28.88 and 22.22%, respectively and exceed to 60.71 and 69.04% at longer exposure of 7 days. Results indicated that mortality of T. castaneum was influenced by interval exposed to wheat treated with SilicoSec and over this exposure; the increases in application rate of SilicoSec had significant effect on the mortality. Young larvae of red flour beetle were more sensitive to SilicoSec than old larvae and adults were more tolerant. Reproductive potential of adults in the treated wheat was suppressed when compared with untreated wheat. The high retention level of SilicoSec (78.62%) was noted in wheat kernels.