Get access

Mating structure and male production in Vespa analis and Vespa simillima (Hymenoptera: Vespidae)

Authors

  • Jun-ichi TAKAHASHI,

    Corresponding author
    1. Laboratory of Systematic Entomology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo,
    2. Honeybee Science Research Center, Tamagawa University, Tokyo,
    Search for more papers by this author
  • Yutaka INOMATA,

    1. Tokachi Subprefectural Office, Hokkaido Government, Obihiro, Japan; and
    Search for more papers by this author
  • Stephen J. MARTIN

    1. Laboratory of Apiculture and Social Insects, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
    Search for more papers by this author

Dr Jun-ichi Takahashi, Center for Ecological Research, Kyoto University, Otsu, Shiga, 520-2113 Japan. Email: jit@ecology.kyoto-u.ac.jp

Abstract

We estimated queen mating frequency, genetic relatedness between workers and worker reproduction in the hornets Vespa analis and Vespa simillima using microsatellite DNA genotyping. The 20 V. analis colonies studied each contained a queen inseminated by a single male. Of the 15 V. simillima colonies studied, nine had a queen inseminated by a single male, four had a queen inseminated by two males, and two had a queen inseminated by three males. The estimated effective number of matings was 1.33 ± 0.74 (mean ± SD), with 75–85% of the offspring of the six multiply mated queens sired by single males. The values for genetic relatedness between the workers of V. analis and V. simillima were 0.739 ± 0.004 and 0.698 ± 0.013 (mean ± SD), respectively. We conclude that V. analis and V. simillima colonies are genetically monogynous and monandrous. When high relatedness between the workers occurs within colonies, kin selection theory predicts a potential conflict between queens and workers over male production. To determine whether males were derived from queens or workers, males from V. analis and V. simillima colonies were genotyped at four microsatellite loci and the level of ovary activation in workers was determined. None of the 787 V. analis workers and only 15 of 3520 V. simillima workers had developed ovaries. Furthermore, the genotyping identified no worker-produced males in any colony. The presence of reproductive workers correlated positively with the number of workers within the colony. These results suggest that eusocial colonies with an annual life cycle tend to break down socially when they become large and are close to dying.

Ancillary