Host plant resistance against Mexican rice borer in rice: Effectiveness, economic benefits and compatibility with other IPM tactics

The Mexican rice borer (Eoreuma loftini) is an invasive Lepidopteran pest affecting rice in Louisiana and Texas, with an expanding range to other states. The current management strategy relies solely on Dermacor X-100 (chlorantraniliprole) seed treatment, which effectively control Mexican rice borer and rice water weevil (Lissorhoptrus oryzophilus). However, single management tactic over a long period of time is unsustainable due to the potential for resistance development. To address this situation and to adopt more sustainable practices, and mitigate resistance development, a field study was conducted at the H. Rouse Caffey Rice Research Station in Louisiana. Four commercially available rice varieties—Cheniere, Jazzman, Mermentau, and PVL03—were planted in April 2024. Seed treatments included Dermacor X-100 for controlling both rice water weevil and Mexican rice borer, and Cruiser (thiamethoxam) and Fortenza (cyantraniliprole) specifically for rice weevil control, along with an untreated control group. Results indicated that yield losses from E. loftini were lower in the resistant varieties Jazzman and Cheniere compared to the susceptible varieties Mermentau and PVL03. Economic returns, calculated using prevailing market prices, showed that resistant varieties with chemical control yielded higher returns than susceptible ones. Therefore, integrating host plant resistance with chemical control can enhance the management of the Mexican rice borer.