Journal of Environmental Biology

Efficacy of novel insecticides against major insect pests of potato in Assam

P. Mili¹, S. Bhagawati¹*, K. Choudhury¹, K. Sarmah², P. Sutradhar³, U. Phukan¹ and E.B. Devi¹     

¹Department of Entomology, Assam Agricultural University, Jorhat-785 013, India

²Department of Biochemistry, Assam Agricultural University, Jorhat-785 013, India

³Department of Agronomy, Assam Agricultural University, Jorhat-785 013, India

Received: 18 August 2025                   Revised: 05 November 2025                   Accepted: 28 February 2026

*Corresponding Author Email : sudhansubhagawati@gmail.com                          *ORCiD: https://orcid.org/0000-0002-9440-5425

Abstract

Aim: Studying the efficacy of novel insecticides against major insect pests of potato.

Methodology: Two consecutive sprays were performed for six novel insecticides in potato and the per cent reduction of both sucking and foliage feeding insects as well as reduction in tuber damage by subterranean insects was calculated out. Additionally, residue of the most promising insecticide was also estimated using RP-HPLC to determine its safety.

Results: Among the tested insecticides, Fipronil 40% + Imidacloprid 40% WG @ 300g a.i. ha^-1 significantly reduced the incidence of aphids (97.61%), flea beetles (91.37%) and hadda beetles (95.83%) as well as registered lowest tuber damage on both weight and number basis (2.44 and 2.43%, respectively) resulting in a marked increase in marketable tuber yield (148.17 q ha^-1) and economic return (2.33). Residue of imidacloprid and fipronil in potato samples was found to be 0.1828 mg kg^-1 and 0.0093 mg kg^-1, respectively, at the time of harvest, which was recorded below the Codex MRL value.

Interpretation: The insecticidal formulation, i.e., Fipronil 40% + Imidacloprid 40% WG when applied @ 300 g a.i. ha^-1 can effectively manage both aboveground and subterranean insect pests of potato due to its dual mode of action with a residue level below MRL values in tubers at harvest signifying a cost effective and environment friendly management option for the potato growers of Assam.

Key words: Evaluation, Fipronil, Imidacloprid, Insect pests, Insecticide, Potato crop

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