Insecticidal Effect of an Enhanced Attapulgite for the Control of Four Stored-Product Beetle Species

Abstract

We examined the insecticidal effect of three different dust formulations, which were attapulgite (W), attapulgite mix with oregano essential oil with 52% carvacrol (D1), and attapulgite mix with oregano essential oil with 75% carvacrol (D2), in four major stored-product beetle species, Sitophilus oryzae (L.), Tribolium confusum Jacquelin du Val, Rhyzopertha dominica (F.), and Trogoderma granarium Everts. Sitophilus oryzae was the most susceptible at all three formulations, followed by T. confusum and R. dominica. In contrast, T. granarium larvae showed the lowest mortality rates even on the 14th day of observation and at the highest concentration (2000 ppm). Progeny production was particularly reduced for all species relative to the controls. Nevertheless, complete suppression of the offspring was observed only in the case of T. confusum and S. oryzae, while R. dominica was less susceptible to all three dust formulations, giving an average of up to 20 individuals per vial at 2000 ppm. To our knowledge, this study is the first that has examined the insecticidal activity of oregano compounds in combination with attapulgite for the control of stored-grain insect species. Additional experimentation is required to indicate the rationale of using these natural resource-based materials under a non-chemical control strategy at the post-harvest stages of agricultural commodities.