Plasticity of female mating behavior drives competitive exclusion of whitefly biotypes

Reproductive interference can affect the quality and quantity of mates and offspring production, yet the effects of such competition on mating behavior and population dynamics are largely unknown. Selection could be strong for flexible mating behaviors that allow individuals to maximize their fitness under competition and avoid displacement. Here we show that females of the B biotype of the haplodiploid whitefly Bemisia tabaci respond to reproductive interference by males of the Q biotype by increasing their acceptance of copulation attempts from B males. This flexible mating behavior contributes to the maintenance of a constant sex ratio despite reproductive interference competition. In contrast, Q females have invariant mating behavior and unstable sex ratio in the presence of reproductive interference from B males. Simulation models incorporating behavioral and life-history data indicate that plasticity in mating behavior and sex ratio of B females is a key determinant of the widespread success of this biotype in displacing competing biotypes. As many haplodiploid species are comprised of biotypes, these findings suggest that plasticity in mating behavior and sex ratio could drive competitive exclusion and affect community structure in many species when previously allopatric biotypes are introduced to the same environment.