Opuntia ficus-indica cladode extract is an embryotoxic, larvicidal, and oviposition-deterrent agent for the diamondback moth, Plutella xylostella

Abstract

The search for new compounds to control Plutella xylostella, the main pest of Brassica crops, has been stimulated by the environmental impact of the insecticides currently used and reports of resistant populations. This work evaluated the effects of a cladode extract from Opuntia ficus-indica (CE) on the survival and development of P. xylostella, as well as on its oviposition behavior. Additionally, the effects on the histological organization of the larval midgut, as well as digestive enzyme activities, were evaluated. CE contained flavonoids, cinnamic derivatives, terpenes, steroids, and reducing sugars. High-performance liquid chromatography analysis confirmed the presence of rutin and compounds containing aliphatic chains and aromatic rings in their structures. CE reduced the viability of eggs with an EC50 (concentration that reduces egg viability by 50%) at 5.37% (w/v) and killed larvae with an LC50 (concentration that kills 50% of larvae) at 7.75% (w/v). Histological analysis revealed several alterations in the midgut of larvae exposed to the extract, including the presence of spherites, cell nuclei expulsion, the disappearance of the peritrophic membrane, and an increase in the number of goblet cells. CE inhibited the in vitro activity of proteases from larvae midgut extracts. The extract also presented oviposition-deterrent activity. In conclusion, cladodes of O. ficus-indica are a source of compounds toxic to eggs and larvae of P. xylostella and are able to interfere with oviposition site choice. The results suggest potential of CE as a botanical insecticide, though field trials are needed to confirm activity.