Physiological and behavioral interactions of a predator with its prey under indirect exposure to the insect growth regulator lufenuron

Abstract

Growth regulating insecticides, such as lufenuron, are recommended for pest management due to their action on the ecdysis process and low toxicity to non-target species. However, these insecticides affect some non-target insects, such as Podisus nigrispinus Dallas, and can interfere with the control of lepidopteran pests by this predator. This study evaluated the impacts of indirect ingestion of lufenuron on the nutritional and histological characteristics of P. nigrispinus, as well as this predator's consumption rate, prey preference, and the weight and nutritional aspects of the prey, Alabama argillacea Hübner. Fourth and fifth instar P. nigrispinus nymphs preying upon A. argillacea larvae fed on cotton leaves that were either untreated or treated with lufenuron were evaluated. For the prey analysis, third instar A. argillacea larvae that had fed on cotton leaves treated or untreated with lufenuron were used. Exposure of P. nigrispinus to lufenuron resulted in a reduction in lipid, sugar, and glycogen contents in fourth instar nymphs; a greater number of treated than untreated prey was chosen by fourth instar nymphs, in a no-choice test; increased lipid content in fifth instar nymphs; histological alterations, such as cellular disorganization and desquamation, lysis of the epithelium; and decreased survival were observed in both evaluation instars. Prey preference was not affected. Lufenuron-treated A. argillacea larvae exhibited a reduction in glycogen content, while prey weight was not affected. These results provide an important resource for pest management decisions, since lufenuron induced biochemical and histological alterations in the midgut epithelium of P. nigrispinus, affecting its survival and possibly compromising its potential as a biological control agent.