Mating between species is common, but seldom adaptive. Mate preferences and receptivity
to mating attempts may both contribute to such matings, also called reproductive interference.
Here, we tested the hypothesis that both male mate preference for female body size
and female receptivity contribute to reproductive interference between two secondarily
sympatric insect species. In north-central Florida, the squash bug Anasa tristis co-occurs
with a recently introduced, smaller congener, Anasa andresii. Male A. andresii are
frequently found copulating with larger female A. tristis in the field. We found that
male A. andresii prefer larger heterospecific females over conspecific females, that
female A. tristis accept some mating attempts by heterospecific males, and that female
A. tristis are more promiscuous with conspecifics than are female A. andresii. Our
findings suggest that both male mate choice and female receptivity contribute to mating
between these species.