Field evaluation of botanicals and entomopathogenic fungi against the mirid bug, Nesidiocoris tenuis (Reuter), on bottle gourd under semi-arid conditions

Abstract

The mirid bug, Nesidiocoris tenuis (Reuter) has emerged as an important sucking pest of bottle gourd, particularly under semi-arid conditions. A field experiment was conducted during Kharif 2024 at Jobner, Rajasthan, India, to evaluate the comparative field efficacy of entomopathogenic fungi and botanical insecticides against N. tenuis and to assess their effects on fruit yield and economic returns. The experiment comprised eight treatments, including Metarhizium anisopliae, Beauveria bassiana, Lecanicillium lecanii, azadirachtin, neem oil, neem seed kernel extract (NSKE), flonicamid 50 WG as a standard check and an untreated control, arranged in a randomized block design with three replications. Flonicamid recorded the highest suppression of N. tenuis, with an overall reduction of 82.25% over the untreated control, followed by azadirachtin (69.84%) and neem oil (66.54%). Among the entomopathogenic fungi, L. lecanii was the most effective, followed by B. bassiana and M. anisopliae. Fruit yield was highest with flonicamid (307.87 q ha⁻¹), followed by azadirachtin (274.70 q ha⁻¹), neem oil (264.30 q ha⁻¹) and NSKE (258.67 q ha⁻¹). A strong positive relationship was observed between mirid bug suppression and fruit yield (R² = 0.992). Flonicamid also recorded the highest incremental cost-benefit ratio (1:29.63), while neem oil showed the highest ICBR (1:29.49) among the eco-friendly treatments. The findings demonstrate that azadirachtin and neem oil have considerable potential as economically viable and eco-friendly options for managing N. tenuis in bottle gourd under semi-arid conditions.