Evaluation of Volatile Compounds in Rice Bugs (Leptocorisa acuta) and Assessing their Behavioral Responses to Different Sri Lankan Rice Varieties

Rice bug (Leptocorisa acuta) is a major pest responsible for significant yield losses in rice. Although conventional chemical insecticides are effective, they pose environmental and health hazards, highlighting need for exploring alternatives such as semiochemicals and bio-insecticides. In Sri Lanka, no prior studies to identify the Volatile Organic Compounds (VOCs) associated with rice bugs. We aimed to characterize VOCs emitted by L. acuta and its behavioral responses over eight Sri Lankan rice varieties (BG 251, BG 257, BG 377, AT 313, BG 360, BG 366, AT 311, AT 362). VOCs were collected from male and female rice bugs (20 individuals per sex, 3 replicates) using dynamic headspace sampling and analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). D-limonene identified as the dominant in females, while 2-octenal was in males. Behavioral assays using a four-choice olfactometer revealed varietal preferences: BG 377 was the most attractive (5.0 ± 0.89, 6.88 ± 2.33, 6.88 ± 1.67), while BG 360 was the least preferred (3.5 ± 0.33, 3.25 ± 0.78, 4.25 ± 0.73). However, statistical significance was only in one instance (p = 0.046), where others non-significant (p = 0.264, p = 0.552). These findings can be used for future development of semiochemical-based pest management.