Inter-geographic hybridization in the corn borer Ostrinia furnacalis reduced the fitness of hybrids

Abstract

It is commonly observed that if the genetic divergences between parental lineages are too marked, the intermixed offspring might not be successful or might present reduced fitness, i.e., hybrid inferiority. In the present study, we performed an intraspecific hybridization using two populations of the Asian corn borer, Ostrinia furnacalis: a southern population (S) from Huizhou city (23.09°N, 114.4°E) and a northern population (N) from Harbin city (44.9°N, 127.2°E). The key life-history traits were compared between the two populations with geographical reproductive isolation and their two hybrid populations (S♀ × N♂ and N♀ × S♂ populations) at 20, 24, 28 and 32 °C. Our results showed that there were significant differences in life-history traits in the two parental populations, with the S population performing better. However, the two hybrid populations exhibited delayed larval development time, relatively reduced body weight, lower growth rate and sex ratio distortion compared with their parents. Our results provided further evidence that intraspecific hybridization between the two geographical populations reduced the fitness of the hybrids. The sexual size dimorphism was also different between the pure populations and the hybrid populations. We also found that the sex ratios in the two hybrid populations were mainly influenced by the genotype of the mothers. The negative effects of intraspecific hybridization on the key life-history traits may provide a genetic means of pest management to suppress pest populations.