Journal of Environmental Biology

Comparative toxicity of biopesticides, synthetic insecticides and fungicides to mycophagous predator Illeis cincta F. (Coleoptera: Coccinellidae)

S. Hariharan¹, P. Duraimurugan²*, D. Neethu Roy² and N. Priyanka³     

¹Division of Entomology, ICAR- Indian Agricultural Research Institute, Hyderabad-500 030, India

²Crop Protection Section, ICAR-Indian Institute of Oilseeds Research, Hyderabad-500 030, India

³Department of Entomology, Professor Jayashankar Telangana Agricultural University, Hyderabad-500 030, India

Received: 02 July 2025                   Revised: 21 October 2025                   Accepted: 15 February 2026

*Corresponding Author Email: duraimuruganp@rediffmail.com                  *ORCiD: https://orcid.org/0000-0002-3688-1589

Abstract

Aim: The present investigation was undertaken to evaluate the comparative toxicity of selected insecticides, fungicides, and biopesticides on different life stages of Illeis cincta (Coleoptera: Coccinellidae) a mycophagous predator.

Methodology: Bioassays were conducted under laboratory conditions (27±2^°C, 60-70% RH) using a Completely Randomized Design (CRD) with thirteen treatments, each replicated thrice. Leaf-dip method was employed for 2^nd instar grubs, topical application for pupae and the dry film residue method for adults. Mortality was recorded over five days and categorized according to IOBC/WPRS toxicity classification.

Results: Profenophos 50 EC was classified as harmful (>99% mortality), causing complete mortality in adults and high mortality in 2^nd instar grubs and pupae. Emamectin benzoate 5 SG, chlorantraniliprole 18.5 SC, and copper oxychloride 50 WP were categorized as slightly harmful (30-79% mortality). In contrast, difenoconazole 25 EC, cymoxanil 8 + mancozeb 64 WP, Bacillus thuringiensis var. kurstaki (Bt-127 SC), Beauveria bassiana SC, Metarhizium rileyi (1×108 CFU ml^-1), Bacillus thuringiensis var. kurstaki + Beauveria bassiana SC, Bacillus thuringiensis var. kurstaki + Metarhizium rileyi SC, and azadirachtin 0.03 EC were rated harmless (<30% mortality), with no significant adverse effects at any life stage of I. cincta.

Interpretation: These findings highlight the ecological safety of biopesticides and selective fungicides as viable alternatives for pest management. Their use can contribute to the conservation of beneficial predators like I. cincta and reduce dependence on broad-spectrum chemical pesticides in agroecosystems.

Key words: Bioassay, Biopesticides, Fungicides, Illeis cincta, Insecticides, Toxicity

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