FACTORS RESPONSIBLE FOR OUTBREAK OF THE RICE HISPA DICLADISPA ARMIGERA (OLIVIER) (COLEOPTERA: CHRYSOMELIDAE) IN RICE FIELD

Abstract

The rice hispa Dicladispa armigera (Olivier) is an occasional pest of rice, but when outbreaks occur, they often cause widespread damage. Reports of rice hispa outbreaks are increasing across Thailand's provinces, with climate change potentially contributing to outbreak frequency in many areas. This research investigated factors influencing current rice hispa outbreaks by analyzing agricultural disaster reports from the Ministry of Agriculture and Cooperatives (July 2010-January 2023) and urgent situation reports (SST. 101) from the Rice Department. A total of 15 documented outbreak events across five central provinces were analyzed for correlations with meteorological factors. Results showed rice hispa outbreaks were significantly associated with wind direction (r = 0.261, p = 0.044, 95% CI: 0.008-0.484), explaining 6.8% of outbreak variance. Southwest and southeast monsoon winds coincided with 73% of recorded outbreaks, supporting atmospheric transport mechanisms for hispa dispersal. Temporal analysis revealed 80% of outbreaks occurred during June-November, with peak activity in 2018 and 2022 accounting for 73% of total events. Artificial neural network modeling using weather factors achieved 61.54% prediction accuracy with cross-validation stability (59.3% ± 4.7%). The study provides the first quantitative evidence for climate-outbreak relationships in Thai rice hispa populations, establishing baseline data for surveillance systems and early warning protocols for integrated pest management in climate-variable environments.