Difference in diel mating time contributes to assortative mating between host plant-associated populations of Chilo suppressalis

Abstract

Behavioral isolation in animals can be mediated by inherent mating preferences and assortative traits, such as divergence in the diel timing of mating activity. Although divergence in the diel mating time could, in principle, promote the reproductive isolation of sympatric, conspecific populations, there is currently no unequivocal evidence of this. We conducted different mate-choice experiments to investigate the contribution of differences in diel mating activity to the reproductive isolation of the rice and water-oat populations of Chilo suppressalis. The results show that inter-population difference in diel mating activity contributes to assortative mating in these populations. In the rice population, most mating activity occurred during the first half of the scotophase, whereas in the water-oat population virtually all mating activity was confined to the second half of the scotophase. However, when the photoperiod of individuals from the water-oat population was altered to more closely align their mating activity with that of the rice population, mate choice was random. We conclude that inter-population differences in diel mating time contribute to assortative mating, and thereby the partial reproductive isolation, of these host-associated populations of C. suppressalis.

Gene flow across host‐associated populations of the rice stem borer Chilo suppressalis Walker (Lepidoptera: Crambidae): implications for Bt resistance management in rice

“…How do we reconcile these patterns of genetic differentiation with the clear differences in mating time and morphometric traits, such as body size and male genital structure? The divergence between these two host‐associated lineages may be relatively recent and the nuclear gene EF1‐α might still be the same across them because of the slow rate of change of this gene. Similarly, the pattern of shared haplotypes across hosts, despite some signal of host association in the mtDNA, could also represent incomplete lineage sorting (where gene lineages have not had sufficient time to accumulate fixed differences), or female specific behavior (which is more evident in mitochondrial data as it is maternally inherited).…”

“…Cross‐mating can occur between rice and water oats C. suppressalis in the laboratory . In these crosses, the rate of mating was significantly different in crosses between females from rice and males from water oats compared with the opposite direction.…”

Age-related mating rates among ecologically distinct lineages of bedbugs, Cimex lectularius

“…Populations of the same species may differ in many aspects, such as density, presence of predators and pathogens, or other ecological variables (Haddrill et al 2013, Valenzuela Sánchez et al 2021). Intraspeci c variation in reproductive behaviour between populations has been widely documented (e.g., Saarikettu et al 2005;Shuker et al 2006, Quan et al 2017. Differences among populations could in uence mating systems such as intrasexual competition, female choice or resistance, optimal mating rates (Kokko & Rankin, 2006), or even lead to reproductive isolation (Olivero et al 2017).…”