Mate‐searching behavior in the invasive German wasp, Vespula germanica, in Patagonia

Abstract

In order to increase the probability of reproduction, social insects can adopt various mate‐finding strategies, such as increasing densities of males at specific locations, and/or visual and chemical cues that attract the opposite sex. In field and laboratory studies we investigated strategies used by the invasive eusocial wasp Vespula germanica (Fabricius) (Hymenoptera: Vespidae). In tethered flight assays, we established contrasting flight patterns in females and males that may partly explain how related individuals distribute spatially during the mating period. We also determined experimentally, in the field and in the laboratory via olfactometer assays, that gynes produce airborne pheromonal cues that attract drones and are important during mate location. Our field trials also suggest that visual cues play a role in mate location. We conclude that in addition to aspects of the social biology of the species, an efficient mate‐location strategy can partly explain the invasion success of the species. Tools to mitigate the damage caused by yellowjackets may be developed by focusing on reproductive castes, in addition to workers.

Drone aggregation behavior in the social wasp Vespula germanica (Hymenoptera: Vespidae): Effect of kinship and density

“…Although these can be relatively large molecules with low volatilities, some of them can be perceived without tactile interaction at short distances, as established through behavioral studies on ants of the www.nature.com/scientificreports www.nature.com/scientificreports/ genus Camponotus and bumblebees, who can discriminate related from unrelated individuals from a short distance [34][35][36] . Having mentioned this, the relevance of visual cues in kin recognition cannot be ruled out, since their role in this aspect has been investigated and they can be important in sexual selection, mate attraction and mate choice 8,31,33,37 . For example, females of Polistes simillimus may evaluate male facial coloration during the choice of a sexual partner 38 .…”

“…With gynes not having a selective behavior toward potential mates, a mechanism to increase outbreeding, regulated by drones, would make sense. It has been recently suggested that dispersal in V. germanica is gyne-biased, while gynes have the potential of flying relatively large distances, drones fly relatively little, which implies remaining in the vicinity of the parental nest, where kin density is high 8,39 . This would suggest that, if no additional mechanism for increasing aggregation heterogeneity was in place, the risk of drone aggregations being conformed by a relatively high proportion of nestmates, would be high.…”

“…Previous studies describing the mating behavior of social wasps have focused mainly on females, and suggest that mating occurs outside nests, mediated by a sexual pheromone produced by females, with mating occurring with one to several drones at random 8,[25][26][27] . Additionally, field observations report loose aggregations of up to several hundreds of males around trees and shrubs 28,29 .…”

Nest-departure behaviour of gynes and drones in the invasive yellowjacket Vespula germanica (Hymenoptera: Vespidae)

“…Particularly in haplodiploid hymenopterans, due to their particular mechanism of sex determination (i.e., single-locus complementary sex-determination system), the costs of inbreeding can be even higher, because sterile diploid males develop and reach the adult stage, representing an extra cost for the colony (Van Wilgenburg et al ., 2006; Tabadkani et al ., 2012). Many hymenopteran species display behaviours that reduce inbred matings, such as mating with more than one male (polyandry), kin recognition and differential spatial and temporal distribution patterns between sexes (Mazzi et al ., 2011; Loyau et al ., 2012; Pizzari and Wedell, 2013; Vitikainen et al ., 2015; Martinez et al ., 2018).…”

“…Some of the studies on reproductive behaviour in V. germanica indicate that mating occurs during the end of autumn, with field observations suggesting that drones emerge ahead of gynes and congregate in specific areas waiting for females to arrive (Spradbery, 1973; Post 1980; Greene, 1991). Gynes can mate more than once (polyandry), with pheromones and visual cues suggested to be involved in mate location (Ross, 1983; Reed and Landolt, 1990; Ayasse et al ., 2001; Goodisman et al ., 2002; Brown et al ., 2013; Loope et al ., 2014; Derstine et al ., 2017; Martinez et al ., 2018). Also, tethered flight bioassays indicate that movement is greater in pre-hibernated gynes than in drones, thus favouring spatial separation (Masciocchi et al ., 2016).…”