Kinship and density in Vespula germanica (Hymenoptera: Vespidae) drone aggregations

CORLEY JUAN CARLOS; MASCIOCCHI MAITÉ; MARTINEZ ANDRES S.; ANGELETTI, BÁRBARA

Congreso; Animal Behaviour Live: Annual Online Conference; 2020

University of Toronto, York (UK) and Queen Mary University of London (UK)

In social insects, whose reproductive individuals generally leave the nest for copulation, mechanisms deployed to minimize inbreeding, such as dispersal and avoidance of relatives, are important for the success of the population. At the time of leaving the nest, the density of related individuals is high, thus favoring inbreeding and, given their sexual determination system (single-locus complementary sex determination), the number of infertile triploid males increases. Vespula germanica is an eusocial and polyandry wasp that has successfully established in different parts of the world, including the Patagonia Argentina. In this study, we ask whether male wasps display specific aggregation behavior that promotes genetic diversity. High levels of genetic diversity in male aggregations could be important to reduce inbreeding, because the high numbers of individuals in aggregations could decrease the probabilities of mating with relatives. Our aim was to establish under laboratory conditions, the effects of relatedness and density in encounters between drones. Based on the assumption that due to the negative effects of inbreeding in hymenopterans, V. germanica drones will promote genetically-diverse aggregations, we expected to find a lower avoidance threshold (i.e. a lower number of drones) toward kin than that toward non-kin. Using a 4-way olfactometer, we evaluated the behavior of drones towards different densities of individuals (2, 6 and 10 drones), related and unrelated. We show that drones avoid aggregating with their nestmates at all densities while non-nestmates are avoided only at high densities. This suggests that genetic diversity and density in V. germanica drone aggregations could be regulated through drone behavior and in the long run minimize inbreeding, thus favoring invasion success. A better understanding of the mechanisms involved in the reproductive process of V. germanica drones, could be important to integrate it into the management programs of this problematic species.