The joint action effects of bioprotective agents on life table indices of Trogoderma granarium Everts (Coleoptera: Dermestidae)

Abstract

Using nature-based substances (diatomaceous earth) and entomopathogenic fungi as grain bioprotective factors in a mixed mode is imperative to manage stored product pests in terms of preserving food safety. Trogoderma granariumEverts (Coleoptera: Dermestidae) biological traits and life table indices of parent and progeny were assessed after exposure toBeauveria bassiana(strain DE) (Hypocreales) dry conidia (LD50 = 295.3 mg conidia kg-1 grain), low lethal dose (mg dust kg-1 grain) of diatomaceous earth formulations including Sayan® (LD25 = 4439.5), and Celite® 610 (LD25 = 992) and their binary mixtures. According to the lethal dose ratio test (LD50), the insecticidal activity of Celite® 610 has 4.47 times more than Sayan®. Nearly all binary mixes exhibited synergistic effects, excluding the last dose of the fungus (LD90), which additively interacted. However, totalpre-adults (days), adults' longevity, and reproductive performance of the beetle were decreased drastically, particularly in a combination of LD50B. bassiana + LD25Celite®610. Besides, the vital progeny population's indices, such as intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and gross reproduction rate (GRR), all were decreased similarly. The lowest r (-0.0004 day −1) and R0 (0.968 offspring per individual) were found in the B. bassiana mixture with a low-lethal dose of Celite® 610. The male-biased sex ratio was notably established after adults' exposure to binary mixtures. Our results demonstrated that both parent and offspring generation of T. granarium incur fitness costs through exposure tobioprotectivesubstancesand especially their mixed modes, resulting in effective suppressing of the adult populations.