Rice earhead bug (REHB), Leptocorisa oratorius (Fabricius), is a serious pest in spring rice, for which sustainable management options are limited. This study evaluated the efficacy of six pesticides, two biorational chemicals: imidacloprid and thiamethoxam, and four biopesticides: azadirachtin, Acorus calamus oil, Jholmal, and Metarhizium anisopliae in addition to control, against REHB in Nepal. The study employed a randomized complete block design with three replications, where treatments were applied twice: (i) when the infestation reached the economic threshold, and (ii) on day-15 of the first application. Data on bug population were recorded at 1, 3, 6, 9, 12, and 15 days after treatment, while crop yield, panicle weight, and grain characteristics were recorded after harvest. Imidacloprid reduced the highest REHB population relative to the control, i.e., 79.11% and 76.42% in the first and second spray, respectively, while thiamethoxam reduced 73.56% (first spray) and 69.10% (second spray). Imidacloprid resulted in the highest yield (3.42 t/ha), followed by thiamethoxam (3.32 t/ha). Notably, Jholmal demonstrated a population reduction of 62.44% and 61.79% relative to control in the first and second spray, respectively, and gave a 3.04 t/ha yield. Therefore, Jholmal is recommended as a strong substitute to chemical pesticides in sustainable pest management interventions of REHB.
Aryal et al. (Thu,) studied this question.