Insecticidal activity of Capsicum annuum L. leaf proteins on cowpea weevil Callosobruchus maculatus (Coleoptera: Bruchidae) development

[Display omitted] •Callosobruchus maculatus is the main pest of Vigna unguiculata seeds.•Proteins of Capsicum annuum leaf interfered with the C. maculatus post-hatching development.•Capsicum annuum proteins decreased insect oviposition and larval mass.•C. annuum protease inhibitor was toxic to C. maculatus larvae.•Larvae fed Capsicum annuum proteins showed changes in energy reserves and digestive enzymes activities. Several antimicrobial peptides (AMPs) from plants of the genus Capsicum have been isolated and characterized, showing biocidal activity. Some of these compounds exhibit insecticidal activity. In this study, we obtained a fraction containing a Pin-II protease inhibitor from the supernatant of the leaf extract of C. annuum and compared the toxicity of this extract supernatant (ExS) with that of the total extract, named Ex, against Callosobruchus maculatus development. Ex and ExS were incorporated into artificial seeds containing cotyledon flour from Vigna unguiculata, which reduced oviposition and interfered with the post-hatching larval development of C. maculatus, causing a reduction in larval mass. A decrease in oviposition of up to 72.6% was observed in artificial seeds containing 15% (m/m) Ex and 2% (m/m) ExS. Decreases up to 60% and 55% were observed in the larval mass at 20 days after oviposition (DAO) for larvae raised on diets containing Ex and ExS, respectively. Alterations in glucose, protein, triglyceride, and cholesterol levels and the activities of α-amylases, cysteine proteases, and lipases were also detected in these larvae. Our data show that Ex and ExS have deleterious effects on C. maculatus, with the potential for developing methods to control this insect, such as products for fumigating grain during postharvest management.