Spread of invasive yellowjacket (Vespula germanica) populations

MASCIOCCHI MAITÉ; CORLEY JUAN CARLOS

Mar del Plata

Congreso; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

Grupo de Investigación y Educación en Temas Ambientales

The spread of exotic species is a central subject 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 spread of the invasive social wasp Vespula germanica in Argentina. V. germanica is native to Eurasia and has invaded southern Argentina in 1980. This wasp has an annual cycle, and new nests are founded by mated queens the following spring. Flight potential of wasp queens was measured using flight mills, under controlled laboratory condition. Also, we mapped current wasp distribution and estimated the rate of spread. The average distance flown by a wasp queen was 404.7 ± 140.8 m (mean ± SE) (n=59). The rate of spread of Vespula germanica in Argentina was estimated at 39.8 ± 2.1 km/year (mean ± SE). The observed spread rates of yellowjackets are 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 these wasps. We suggest that despite several life-history traits known for social insects that contribute to successful invasion during the establishment phase, stratified 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 these pestiferous wasps.