Insecticidal and antifeeding activity of several botanicals against Rhyzopertha dominica Fabricius

Abstract: Rhyzopertha dominica (Fabricius) is one of the most important pests of wheat during storage. It leads to reduction in quality, quantity and marketability of this crop. This is why the prevention of food losses during storage is of great economic importance. Recently, there has been a growing interest in the use of plant-based preparations (botanicals), as alternatives to chemical insecticides. The aim of this work was to assess the insectidical and antifeeding activity of Verbascum nigrum, Echium italicum and Erigeron canadensis (0.5, 1, 2%) ethanol extracts and botanical insecticides based on pyrethrin (0.01, 0.02, 0.05%) and azadirachtin (0.75, 1.5, 3%), on R. dominica adults. Insecticidal effects were determined in contact-digestive “No-choice” test on wheat grains, 24, 48, 72 h and 7 days after the treatment. Antifeeding effect was assessed based on the amount of consumed grains after 7 days, and according to AFI values. High mortality of R. dominica was recorded in treatments with pyrethrin (62.5-100%) and azadirachtin (74.5-100%), regardless on exposure periods and applied concentrations. Satisfactory mortality was after 24 h in treatment with 2% V. nigrum (43.7%), 48 h with E. italicum (42.0%) and after 72 h and 7 days in 2% V. nigrum (68.7, 75.5%, respectively), E. italicum (67.5, 88.0%, respectively) and E. canadensis (53.5, 63.5%, respectively). AFI values indicate that only 2% extracts of V. nigrum and E. italicum expressed slight antifeeding activity.