QUEENS DISPERSAL AND SPREAD OF INVASIVE YELLOWJACKETS (VESPULA GERMANICA) POPULATIONS IN ARGENTINA

MAITE MASCIOCCHI; CORLEY J.C.

Congreso; BIOLIEF 2011; 2011

 of invasion ecology that may be pinned down to two prevailing population processes: reproduction and dispersal. Many invaders can display stratified dispersal that implies an increased rate of spread. We studied the dispersal capacity and spread of the invasive Vespula germanica in Argentina. This social wasp is  native to Eurasia and has invaded Argentina in 1980. The species has an annual cycle, and new nests are started by dispersing queens each spring. Flight potential of queens was measured using flight mills, under controlled laboratory condition. We also mapped current wasp distribution and estimated spread rates. The average distance flown by a wasp queen was 404.7 ± 140.8 m (mean ± SE) (n=59). In turn, the rate of spread of yellowjackets was estimated at 39.8 ± 2.1 km/year (mean ± SE). The observed spread of wasps in Argentina is among the highest known for exotic insects, and confirm the invasive potential shown by several hymenoptera species worldwide. Still, a stratified geographical expansion pattern does not match queen dispersal abilities, suggesting that human aided transport of hibernating queens is the central driver of the current distribution of yellowjackets. We suggest that despite several life-history traits of social insects that are known to contribute to successful invasion during the establishment phase, spread within invaded areas must still rely strongly on human pathways. This observation sheds light on those features that are crucial for managing the invasions of this and related pestiferous wasps.