Fumigant activity of Elsholtzia stauntonii extract against Lasioderma serricorne

Abstract

The repeated use of phosphine over decades for the control of the cigarette beetle (Lasioderma serricorne), a significant stored-product insect worldwide, has led to serious negative effects, including strong insecticide resistance, disruption of biological control by natural enemies, and environmental and human health concerns. As an environmentally friendly alternative to synthetic pesticides, plant-derived pesticides have been the focus of much research. We investigated the fumigant activity of whole plant extracts of Elsholtzia stauntonii, a Chinese mint shrub, against the adult, larval, pupal and egg stages of L. serricorne. E. stauntonii extracts exhibited strong fumigant toxicity against L. serricorne; larvae and adults were more susceptible to this toxicity than were eggs and pupae. The toxicity significantly increased with increasing dosage. The corrected mortality of larvae, adults, pupae and eggs reached 99.32%, 97.97%, 44.67% and 33.33%, respectively, at a dosage of 40 µL/L air after 48 h of exposure. The declining order of susceptibility of different developmental stages of L. serricorne to E. stauntonii extracts, as indicated by the concentration at which 50% of the insects died (LC50), was as follows: larvae (LC50= 8.82 µL/L air), adults (LC50= 10.99 µL/L air), pupae (LC50= 45.96 µL/L air) and eggs (LC50= 84.57 µL/L air). The results suggest that E. stauntonii extracts show promise as a fumigant for the control of L. serricorne.