Evaluation of biocontrol potential of Euphlyctis adolfi and Duttaphrynus melanosticus (Anura: Bufonidae) against rice insect pests under field conditions

Aim: This study investigated the potential of two anuran species, Euphlyctis adolfi (frog) and Duttaphrynus stomaticus (toad), as biological control agents under the agricultural ecosystem of rice fields, using the varieties PR 121 and PR 122 during 2023. Methodology: Frogs were introduced at four densities (4, 8, 12, and 16 frogs 24 m-2) into selected rice plots, along with pesticide-treated and untreated control plots, each replicated thrice. Pest populations and crop damage were monitored weekly using standardized visual inspection and sweep net methods. Results: Arthropod community in rice crop fields comprised of 22 species across six orders and 16 families, orthoptera being predominant. Results demonstrated an inverse relationship between anuran density and arthropod populations, where E. adolfi showed higher efficacy than D. stomaticus. At 16 frogs 24m-2 density, E. adolfi reduced insect population by 15.8% and predator populations by 6.7% as compared to controls, while D. stomaticus achieved 8.3% and 5.2% reductions, respectively. E. adolfi was particularly effective against white-backed planthoppers (35.6% reduction) and grasshoppers (15.4% reduction in crop damage) as compared to controls. Both anuran species had limited impact on rice stem borers due to it's endophytic lifecycle. Pesticide treatments, being more effective provide 70.7% reduction in pest populations, caused substantial decrease in predator populations (32% reduction). Interpretation: The study revealed that anurans, especially E. adolfi, offer balanced approach to pest management as compared to pesticides potentially contributing to sustainable rice cultivation. Findings suggest that anuran integration into pest management strategies could maintain ecological balance while providing effective biological pest control in rice ecosystem. Key words: Anurans, Biological control, Frog, Rice crop, Toad