Mating structure and male production in the giant hornet Vespa mandarinia (Hymenoptera: Vespidae)

Abstract

Queen mating frequency, genetic relatedness between workers and worker reproduction were estimated in Vespa mandarinia by microsatellite DNA markers. Of 20 colonies examined, eighteen contained queens inseminated by a single male and two colonies contained queens inseminated by two males. The estimated effective number of matings was 1.03 ± 0.023 (mean ± SE) with 85% of the offspring of the two multiply-mated queens being sired by one of the two males. The genetic relatedness between workers was 0.738±0.008, which was almost identical to the predicted value of 0.75 under monogyny and monandry. For this low paternity, kin selection theory predicts a potential conflict between queens and workers over male production. To learn whether males are derived from queens or workers, 400 males from 20 colonies were genotyped at four microsatellite loci. We found that queens produced all males. This finding was confirmed by the observation that 4,317 dissected workers had not developed ovaries. There was no relationship between queen mating frequency and the frequency of worker reproduction, and workers did not produce any male offspring. These results strongly suggest that male production dominated by queens in V. mandarinia is possibly due to worker policing.