Diabrotica v. virgifera Seems Not Affected by Entomotoxic Protease Inhibitors from Higher Fungi

• Published in: Insects (Basel, Switzerland) Switzerland), 2024-01, Vol.15 (1), p.60
• Main Authors: Toepfer, Stefan, Toth, Szabolcs, Zupan, Tanja, Bogataj, Urban, Žnidaršič, Nada, Ladanyi, Marta, Sabotič, Jerica
• Format: Article
• Language: English
• Subjects: Adaptation; Adults; Artificial diets; Beetles; Bioassays; Chromatography; clitocypin; cocaprin; Coleoptera; Corn; cospin; Cysteine; Cysteine proteinase; Diabrotica virgifera virgifera; Digestion; digestive proteases; Digestive system; Eggs; Enzymes; Fungi; Gastrointestinal tract; Hatching; Insecticide resistance; Insecticides; Insects; Larvae; macrocypin; Microscopic analysis; Mortality; Mushrooms; Neonates; Pest control; Pest resistance; Pesticides; Pests; Potatoes; Protease; Protease inhibitors; Proteinase inhibitors; Proteins; Proteolysis; Serine proteinase; Soil microorganisms; Soils; Toxicity; Vegetables; western corn rootworm
• ISSN: 2075-4450; 2075-4450
• DOI: 10.3390/insects15010060

Certain soil insects, such as the root-damaging larvae of the maize pest (Coleoptera: Chrysomelidae), are increasingly difficult to control because of recent bans of some insecticides. An alternative and safer approach may be the development of biopesticides based on entomotoxic defense proteins of higher fungi. Many of these potentially interesting proteins are protease inhibitors, and some have been shown to adversely affect insects. We examined the effects of the cysteine protease inhibitors macrocypin 1, 3, and 4 from , clitocypin from , and cocaprin 1 and the serine protease inhibitor cospin 1 from on . We confirmed the inhibition by mycocypins of the cysteine catalytic-type proteolytic activities in gut extracts of larvae and adults. The inhibition of Glu-Phe-Leu-hydrolyzing activity was stronger than that of Z-Phe-Arg-hydrolyzing activity. Mycocypins and cospin resisted long-term proteolytic digestion, whereas cocaprin 1 was digested. Bioassays with overlaid artificial diet revealed no effects of proteins on neonatal mortality or stunting, and no effects on adult mortality. Immersion of eggs in protein solutions had little effect on egg hatching or mortality of hatching neonates. Microscopic analysis of the peritrophic matrix and apical surface of the midguts revealed the similarity between larvae of and the chrysomelid , which are sensitive to these inhibitors. The resistance of to fungal protease inhibitors is likely due to effective adaptation of digestive enzyme expression to dietary protease inhibitors. We continue to study unique protein complexes of higher fungi for the development of new approaches to pest control.