Abstract
The present study was conducted to evaluate the insecticidal activity of three diatomaceous earth (DE) products, SilicoSec (Biofa GmbH, Munsingen, Germany), Protect-It (Hedley Technologies Inc., Canada), and Mamaghan. The silica aerogel was mixed to enhance the efficacy of Mamaghan DE with 10, 15, and 20% rates. The DE products were applied at treatment rates of 100, 200, and 400 ppm against adults of Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). In the second experiment, 0.1 and 0.5% deltamethrin was added to Mamaghan DE–10% silica aerogel to enhance the activity of the DE. Adult mortality was recorded 2, 5, 7, 10, and 14 d after exposure. Parental adults were removed after 14-d exposure time and progeny developed was evaluated after 65 d. Mamaghan–15 and 20% silica aerogel caused the highest mortality (>97%) against T. confusum after 10 d of exposure at the highest dose of 400 ppm which exceeded to 100% mortality after 14 d. However, the toxicity of Mamaghan DE against R. dominica was lower than that of the two commercial formulations at all dose rates. The presence of 0.1% deltamethrin increased the insecticidal activity of Mamaghan DE and significantly suppressed progeny production of both species. Even at the lowest dose of Mamaghan–10% + 0.1% deltamethrin, progeny production of both species was very low (four or less individuals per vial). However, no progeny was recorded in Mamaghan–10% + 0.5% deltamethrin. Thus, adding low rates of silica aerogel and deltamethrin considerably enhanced the efficacy of Mamaghan DE in controlling T. confusum and R. dominica.
Evaluation of Insecticidal Activity of Plant Extracts against Three Insect Pests
