Work

Enhanced toxicity of diallyl disulfide and carvone nanoemulsions against a stored bean pest and their nontarget effects on its parasitoid and seed viability

Year: 2026

Type: article

Abstract: Botanical essential oils and their volatile constituents are increasingly recognized as environmentally safer alternatives to synthetic insecticides for managing stored-product pests. The adzuki bean beetle, Callosobruchus chinensis , is a cosmopolitan pest that causes substantial postharvest losses in legumes. In this study, nanoemulsions (NEs) of diallyl disulfide (a garlic-derived organosulfur compound), (R)-carvone (a spearmint-derived monoterpenoid), and their binary mixtures (1:1 and 2:1) were formulated using ultrasonication. The nanoemulsions consisted of spherical droplets (54–62 nm) and moderately high zeta potentials (−9.6 to −16.9 mV). Among treatments, diallyl disulfide NE exhibited the highest fumigant toxicity to C. chinensis , with an LC 50 of 0.79 µL active compound/L air at 24 h. Nanoemulsification enhanced efficacy by 30.5% for diallyl disulfide and 8.19% for carvone. Binary mixtures showed additive toxicity. Male beetles were generally more susceptible than females, except at a low concentration of the 1:1 mixture. At the 24 h LC 50 estimated for the host beetle, diallyl disulfide NE and the 2:1 mixture were less toxic (<50% mortality) to the parasitoid Anisopteromalus calandrae adults. These treatments, particularly the 2:1 mixture, increased root length and seedling vigor index, with no measurable phytochemical residues on bean surfaces. Exposure of host larvae to diallyl disulfide NE increased total host mortality and parasitoid emergence. Overall, diallyl disulfide NE, alone or in a 2:1 mixture with carvone, showed strong potential as a plant-based fumigant against C. chinensis , with comparatively low adverse effects on the parasitoid longevity, positive diallyl disulfide NE effects on parasitism, and neutral or positive effects on seedling growth.

Source: Ecotoxicology and Environmental Safety

DOI: 10.1016/j.ecoenv.2026.120374

Authors: Urvashi Sahu, Eman Ahmed Mohamed Helmy, Midori Tuda

Institutions: Kyushu University, Al-Azhar University

Language: English

Topic: Insect Pest Control Strategies

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: gold

Estimated APC paid: $3,650