Non-proteinaceous salivary compounds of a predatory bug cause histopathological and cytotoxic effects in prey.

ABSTRACT

N,N-dimethylaniline and 1,2,5-trithiepane, present in the salivary glands of Podisus nigrispinus Dallas (Heteroptera Pentatomidae), are toxic compounds which kill prey. The insecticidal activity and midgut cytotoxicity in Spodoptera frugiperda (J. E. Smith (Lepidoptera Noctuidae) caterpillars fed on a diet with lethal concentrations of N,N-dimethylaniline and 1,2,5-trithiepane were evaluated. Midgut cell damage was evaluated with both light and transmission electron microscopy. The LC50 and LC90 of N,N-dimethylaniline were 0.611 and 0.818 µg L-1, respectively, and for 1,2,5-trithiepane they were 0.671 and 0.885 µg L-1, respectively. Vacuolization in the digestive and goblet cells occurred after 1 h of exposure in the midgut of the insects treated with either N,N-dimethylaniline and 1,2,5-trithiepane. Changes caused by N,N-dimethylaniline and 1,2,5-trithiepane in the midgut of S. frugiperda caterpillars may affect digestion and nutrient absorption with negative impacts on the insect's development and survival. The non-proteinaceous N,N-dimethylaniline and 1,2,5-trithiepane compounds have insecticidal effects, confirming the potential use on S. frugiperda caterpillars through oral administration.