Abstract:  【Aim】 This study aims to explore the variation among geographical populations in the olfactory response of male moths of Chilo suppressalis to sex pheromone and the related mechanisms, so as to understand the olfactory adaptation of male adults in field populations of the pest and its characteristics. 【Methods】 The male moths of C. suppressalis were trapped in rice fields in six provinces of China by using seven lures containing 3-component sex pheromone blends of Z11-16∶Ald and Z9-16∶Ald at different ratios (540 μg∶540 μg, 864 μg∶216 μg, 945 μg∶135 μg, 980 μg∶98 μg, 1 003 μg∶77 μg, 1 016 μg∶64 μg and 1 045 μg∶35 μg) and Z13-18∶Ald with the constant content, the behavioral responses of male moths of the overwintering generation and the second generation trapped by the lures containing Z11-16∶Ald and Z9-16∶Ald at the ratios of 864 μg∶216 μg, 980 μg∶98 μg and 1 016 μg∶64 μg in the filed to the lures at these three ratios were determined by laboratory bioassay in the wind tunnel, and the expression levels of 12 genes involved in sex pheromone recognition in the antennae of male moths trapped by the seven lures containing sex pheromone blends at different ratios were detected by RT-qPCR. 【Results】 In the field tests, all sex pheromone lures containing different Z11-16∶Ald and Z9-16∶Ald ratios could attract male moths of C. suppressalis, but the proportions of male moths of C. suppressalis trapped by lures containing different Z11-16∶Ald and Z9-16∶Ald ratios were different. The optimal ratio of Z11-16∶Ald and Z9-16∶Ald was different among the six provinces, and the proportion of male moths of C. suppressalis trapped by lure containing the same Z11-16∶Ald and Z9-16∶Ald ratio was different among the six provinces. The results showed that not only the optimal ratios of sex pheromones of lures in different geographical locations were different, the proportions of moths attracted by sex pheromone blends at different ratios in different geographical locations were also different. In the laboratory wind tunnel bioassay, the behavioral responses of male moths trapped by lures containing Z11-16 Ald and Z9-16∶Ald at the ratios of 864 μg∶216 μg and 1 016 μg∶64 μg in the field to the lures at the ratios of 864 μg∶216 μg and 1 016 μg∶64 μg, respectively, were significantly higher than those to the lures at the other two ratios. However, the male moths trapped by the lure containing Z11-16∶Ald and Z9-16∶Ald at the ratio of 980 μg∶98 μg in the filed did not show significantly different behavioral responses to lures containing Z11-16∶Ald and Z9-16∶Ald at the ratios of 1 016 μg∶64 μg, 980 μg∶98 μg and 864 μg∶216 μg in the wind tunnel. In the RT-qPCR assay, except GOBP1, the expression levels of the other 11 genes involved in sex pheromone recognition in the antennae of the male moths of C. suppressalis trapped by lures containing Z11-16∶Ald and Z9-16∶Ald at different ratios were significantly different. In addition, there were significant linear correlations between the ratio of sex pheromone blends and the expression levels of genes PBP3, PBP4, PR1, PR2, PR4, PR5 and PR6.【Conclusion】 This study identified the variation in sex pheromone recognition of male moths among different geographical populations of C. suppressalis in China. The results not only contribute to the control of C. suppressalis, but also help to understand the mechanisms of its geographical variation in olfaction.

Key words: Chilo suppressalis, sex pheromone, olfaction, population variation, trapping, wind tunnel