Entomotoxic activity of Eragrostis plana Nees extract on the central and peripheral nervous systems of cockroaches Nauphoeta cinerea Olivier

Abstract

Eragrostis plana Nees is a C4 perennial plant that exhibits toxic inhibitory action on other plants and has demonstrated an entomotoxic potential, although poorly elucidated, in cockroaches of the species Nauphoeta cinerea. The objective of the study was to evaluate the mechanisms involved in the entomotoxic activity of the hydroalcoholic extract of E. plana on the nervous system of N. cinerea. Aerial parts of E. plana were crushed to obtain the hydroalcoholic extract (EHEP). The concentrations (0.5; 2.5; 5.0; 12.5; 25.0; 50.0 100.0 μg g^-1 per animal) were prepared and saline solution was used for the control treatment. The effect of EHEP on the behavioral (self-hygiene), electrophysiological and biochemical patterns of N. cinera was tested. Data were expressed as mean ± standard deviation and were analyzed by two-way ANOVA followed by Tukey's test when considered significant at p < 0.05. An increase in leg grooming activity was observed when the animals were treated with EHEP. The quercetin compound observed in the phytochemical profile of E. plana was shown to modulate the leg and antennae grooming activity of N. Cinera.  EHEP also significantly altered locomotion and inhibited the activity of the enzyme acetylcholinesterase (AChE). Thus, this study corroborates our previous studies on the entomotoxic potential of E. plana and suggests a possible biotechnological potential for the species as a bioinsecticide, due to its modulations on the main signaling pathways of invertebrates.