Post-ingestive effects of flavonoids in the midgut epithelium of Anticarsia gemmatalis (Hübner 1818) (Lepidoptera: Erebidae) larvae

Abstract

An alternative control to soybean caterpillar has been the use of insect resistant plants that present phenolic flavonoids. The midgut is the main access pathway of food and chemical substances ingested. The present study examined morphological alterations in the midgut epithelium of the soybean caterpillar, after the ingestion of soybean genotypes containing the flavonoids rutin and genistin. The caterpillars and genotypes (BRS 257 - control, BR 16, Dowling, PI 229358, IAC 100 and PI 227687) were obtained from the insect rearing facility at the Embrapa Soja. The midguts were collected, fixed in Karnovsky, processed and analyzed under a light microscope. All treatments caused alterations in the midgut epithelial cells. These alterations in the columnar cells were more assiduous than the on other cell types, showing an increase of cytoplasmic protrusions and vacuoles. The goblet cells showed few changes for all genotypes tested, while the regenerative cells presented alterations mainly for the Dowling and PI 227687 treatments. The peritrophic membrane was absent for genotypes IAC100 and PI 227687. We conclude that the Dowling and PI 227687 genotypes were effective and promoted great morphological alterations in the midgut of the soybean caterpillars, being able to be very effective for the control of this plague.