The Entomotoxic Fungal Lectin Marasmius oreades Agglutinin Disrupts the Midgut Epithelium of Colorado Potato Beetle Larvae

TL;DR

A fungal lectin called MOA disrupts the gut of Colorado potato beetle larvae, showing potential as a selective bioinsecticide with minimal harm to bees.

Contribution

MOA is identified as a novel bioinsecticide candidate with selective toxicity against CPB larvae.

Findings

MOA caused higher mortality in CPB larvae compared to other lectins.

MOA disrupts midgut epithelium by binding to glycoproteins and causing structural damage.

MOA showed no acute toxicity to honeybees but affected larval development.

Abstract

Fungal lectins, with their specific glycan-binding activity,
represent
promising biopesticide candidates. This study investigates the potential
of six fungal lectins to control Colorado potato beetle (CPB) larvae
(Leptinotarsa decemlineata). In vitro feeding trials with recombinant lectins were performed
to evaluate their individual toxicity. Marasmius oreades agglutinin (MOA) caused significantly higher mortality than the
other lectins, whereas Coprinopsis cinerea lectin 2 (CCL2) and Aleuria aurantia lectin (AAL) completely inhibited weight gain. Functional analysis
of MOA mutants revealed that both carbohydrate-binding and proteolytic
domains are essential for toxicity. MOA binds to midgut glycoproteins
in CPB larvae, disrupting midgut epithelium. Histology and ultramicroscopy
showed that MOA causes loss of apicobasal polarity and detachment
of basal lamina. No acute toxicity of lectins against adult European
honeybees (Apis mellifera) was found;
however, significant sublethal effects on larval development were
observed. MOA shows promise as a selective bioinsecticide for sustainable
CPB control with minimal nontarget effects.

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