Selectivity of Botanical and Synthetic Insecticides on Doru luteipes: There Is No Simple Answer.

Abstract

To achieve sustainability in agricultural pest management, it is essential to integrate chemical and biological control by using selective insecticides. In this study, we evaluated the lethal and sublethal effects of both botanical and synthetic insecticides used for controlling the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), on its natural enemy Doru luteipes (Scudder) (Dermaptera: Forficulidae). For this purpose, bioassays of mortality, behavior, and transgenerational effects were conducted. Botanical insecticides rich in acetogenins and limonoids caused less than 30% mortality in D. luteipes nymphs (2nd, 3rd, and 4th instars). In contrast, chlorantraniliprole-based insecticide (Premio®) was highly toxic, presenting mortality above 80% at all nymphal stages and reducing predation capacity by 55.9% and walking velocity by 28.4% compared to the control. Aqueous emulsion of the ethanolic extract from Annona mucosa seeds (ESAM) reduced the longevity of the adults by 32.72 days compared to the control. Chlorantraniliprole resulted in the shortest pre-oviposition period (9.4 days), followed by a limonoids-based botanical insecticide (Azamax®) (11.0 days). Fourth-instar nymphs of the F₁ generation showed lower viability (54.5%) in the treatment with aqueous emulsion of the methanolic fraction from Annona montana leaves (EFAMON). The annonin-based commercial botanical insecticide (Anosom®) affected life table parameters, reducing the intrinsic growth rate (r_m = 0.039) and finite rate of increase (λ = 1.04). These findings indicate that, under the specific exposure conditions used in this study, botanical insecticides are less hazardous to the natural enemy D. luteipes than synthetic insecticide. The data obtained highlight the selectivity of botanical insecticides and one synthetic insecticide for improving pest control while preserving natural enemies.