Bioefficacy of eight different plant powders applied as fumigants against the adzuki bean weevil, Callosobruchus chinensis

The adzuki bean weevil, Callosobruchus chinensis (L.), is a highly destructive pest of stored legumes. This study aims to evaluate the bioefficacy of eight plant powders applied as fumigants against C. chinensis. Among the evaluated plant powder fumigants, clove, holy basil, lemongrass, and turmeric powder fumigant elicited high mortality up to 100% of C. chinensis and simultaneously showed high oviposition deterrence and F1 progeny inhibition against the pest, which led to a lower percentage of bean damage and weight loss. The antifeedant activity of the plant powder fumigants is reflected by the high feeding deterrence value of up to 82.92%. Additionally, based on a two-choice test assay, it is revealed that clove, holy basil, lemongrass, and turmeric powder fumigant also have adult repellent activity. Analysis of the volatile organic compounds of those four plant powder fumigants indicated that the major constituents responsible for the anti-pest feature were eugenol and caryophyllene for clove; estragole for holy basil; α-Citral and β-Citral for lemongrass; and α-zingiberene and β-sesquiphellandrene for turmeric. However, clove powder was proved to be the most efficacious fumigant in all parameters observed since it showed high bioefficacy even when applied at the lowest dose. Our findings highlight the potential use of plant powder fumigant as an eco-friendly and cost-effective management method of stored product pests, which could be a valuable option for small-hold farmers in developing countries.