Non-random mating between Boophilus microplus and hybrids of B. microplus females and B. annulatus males, and its possible effect on sterile male hybrid control releases.

When Boophilus microplus and Type-II hybrids (B. microplus females X B. annulatus males) were released simultaneously onto bovine hosts, mating between the two forms appeared not to be at random. There were more contypic and fewer intertypic matings than predicted under an assumption of panmixia. An examination of the patterns of matings revealed that more of the matings on the first two days of detachment were between the two sexes of B. microplus. Engorged females dropping on the last four days of maximum female detachment were predominantly hybrids mated to both B. microplus and hybrid males. The non-random mating pattern does not appear to be caused by assortative mating between B. microplus and Type-II hybrids, but because the B. microplus were competent to mate two days before the hybrids and the B. microplus males compete for males of both types better than the Type-II males.