Entomotoxic properties of Dioclea violacea lectin and its effects on digestive enzymes of Anagasta kuehniella (Lepidoptera)

•DVL intake caused decreased larval mass and prolonged larval stage.•DVL is highly resistant to proteolysis by midgut proteases.•DVL decreased in vivo α-amylase, trypsin- and chymotrypsin-like activities.•DVL binds to the peritrophic membrane.

Entomotoxic plant lectins have been extensively studied in the past two decades, yet the exact mechanisms underlying their toxic effects remain unknown. This study investigated the effects of Dioclea violacea lectin (DVL) on larval development in Anagasta kuehniella. Chronic exposure of larvae (from neonates to the fourth instar) demonstrated that DVL interfered with larval growth, retarding development and decreasing larval mass without affecting survival. DVL decreased trypsin-like, chymotrypsin-like, and α-amylase activities and proved resistant to proteolysis by midgut proteases up to 24 h. Shorter exposures to dietary DVL had no effect on midgut enzyme activity. Feeding fourth-instar larvae with fluorescently-labeled DVL revealed lectin binding to the peritrophic membrane.

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