Laboratory and field studies demonstrating the insecticidal potential of diatomaceous earth against wheat aphids in rice-wheat cropping system of Punjab (India)

Aphids have acquired the status of major pest in North-western plains of India. A complex of five species infests the wheat in this part of the country. The diatomaceous earth (DE) has the potential to substitute the most widely used method of chemical control. Laboratory and field investigations were conducted to evaluate the effectiveness of DE either as soil or foliar application for suppression of wheat aphids during 2013–2014 and 2014–2015. The fecundity, adult longevity and total developmental duration of Rhopalosiphum padi decreased with the increasing dosage of soil application of DE in laboratory evaluation. However in field studies, no significant difference in aphid population was observed among different levels of DE application in soil. Foliar application of DE 150 kg/ha and higher dosages significantly reduced aphid population for initial two days but thereafter it had no effect on aphid prevalence. Wheat plant dusted with different dosages of DE did not show any visible injury but the reduction in chlorophyll content was observed in them. Overall, poor field efficacy coupled with loss of chlorophyll and safety issues relating to foliar application of DE proved against its use for control of sucking insect pests