Effect of various plant powders on rice weevil ( Linn.) in stored wheat

Now-a-days usage of chemical insecticides has become more restricted and creating many environmental problems. Therefore, objective of the present study was to evaluate the alternative control measures in form of botanicals against rice weevil (Sitophilus oryzae L.) on stored wheat. Six botanicals in powder form viz., neem leaf powder (NLP), neem kernel powder (NKP), dharek leaf powder (DLP), dharek kernel powder (DKP), castor leaf powder (CLP) and castor kernel powder (CKP) each at the rate of 1.0, 1.5 and 2.0 % (w/w) were tested by directly mixing into wheat grains against S. oryzae. An aliquot of 100g wheat sample was used in each treatment for maximum of 3 replications. Three jars were also kept for untreated control. Three jars of Deltamethrin 2.8 EC were also kept as standard check. Five pairs of 1-2 week old adult insects (1:1 female to male ratio) were released into each jar. The open tops of all the jars were covered with muslin and kept inside BOD incubator at 27±1 °C and 70±5% R.H. Deltamethrin 2.8 EC was highly effective as all the adult insects were died within 24 hours after their release. Among various powders, NKP at 2% was found best as it showed minimum grain damage (3.84%), weight loss (1.15%) and adult emergence (16.17), while maximum inhibition rate (92.58%) over the untreated control with maximum grain damage (21.16%), weight loss (13.83%) and adult emergence (157.58 adults). The NKP was followed by DKP, NLP, DLP, CKP and CLP. Seed viability was not adversely affected by any of the plant powders used in the studies. This study showed that 2% NKP the most effective compound over the other compounds and untreated control, and it can be used as botanical against S. oryzae in stored wheat.