Opuntia ficus-indica cladode extract is a phagostimulant agent that impairs the morphophysiology of midgut of Spodoptera frugiperda (Lepidoptera: Noctuidae) caterpillars

Abstract

The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous insect whose control mainly involves the use of synthetic insecticides that can be highly toxic to non-target organisms and lead to the selection of resistant populations. This work reports the effects of the saline extract of Opuntia ficus-indica cladodes (CE) on the feeding survival and midgut morphophysiology of S. frugiperda third instar caterpillars. CE exerted a phagostimulant effect to the caterpillars but was not able to kill them. Despite of this, the midguts of caterpillars treated with CE (12.8 mg/g) showed intense disorganization of epithelium, vacuolation of the cytoplasm of columnar cells and increased size of goblet cells, as well as absence of the peritrophic membrane. The caterpillars treated with CE showed a reduction in the amount of neutral polysaccharides and protein content at the midgut epithelial cells. Together these data may indicate that the ingestion of CE in higher concentrations or by a longer period would lead the caterpillars to death or to damage in development. In conclusion, CE ingestion resulted in damage to the midgut morphology of caterpillars, with a reduction in carbohydrate and protein content.