Heterospecific interference modulates the reproductive traits of a ladybird beetle

Abstract

Reproductive interference between species is vital to understand interspecific interactions along with their ecological and evolutionary patterns in nature. We studied potential reproductive interference between two sympatric species of ladybird beetles Propylea dissecta and Cheilomenes sexmaculata (Coleoptera: Coccinellidae). Our aim was to determine whether heterospecific matings occur between these two species, and if so, how they affect the reproductive output of females of both species. We found that heterospecific mating occurs, with P. dissecta females mating with C. sexmaculata males, but not vice versa. To compare the effect of conspecific and heterospecific males on the reproductive output of P. dissecta females, we used two mixed mating treatments: conspecific mixed (an additional P. dissecta male with conspecific pair of P. dissecta), and heterospecific mixed (a C. sexmaculata male with conspecific pair of P. dissecta). We found that conspecific interference did not affect reproductive parameters. However, the presence of a heterospecific C. sexmaculata male interfered with conspecific matings in P. dissecta through multiple mating attempts, resulting in reduced fitness and reproductive success of P. dissecta. Our results indicate that the presence of heterospecific males significantly affected the reproductive output of P. dissecta, apparently as a result of the greater attempted mating activity of C. sexmaculata males. Our findings may be relevant for effective biocontrol strategies involving these insect species.