Biological parameters of the predator Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae) exposed to deltamethrin

Abstract

Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) is a biological control agent whose efficacy may be affected by insecticides. The effects of Decis 25 EC® (deltamethrin) were evaluated through the provision of treated pupae of Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) on the mortality, longevity, and reproduction of the predator. Individuals were exposed to three treatments: control, commercial dose, and double the dose. No mortality was observed in the first 24 hours, suggesting initial avoidance of contaminated prey. After 48 hours, mortality reached 20% in the insecticide treatments. Female longevity was not affected (30.4-41.2 days), whereas male longevity was reduced at higher doses. The number of egg masses decreased in exposed females. Although the total number of eggs was higher at the double dose, than at the lower insecticide doses, embryonic viability was reduced to 33.78%, compared to 90.69% in the control. The incubation and reproductive period were not altered. The results indicate that, despite some tolerance in adults, deltamethrin affects reproduction and offspring viability, requiring caution in integrated pest management programs that combine this insecticide with P. nigrispinus.