Long-term coexistence of two invasive vespid wasps in NW Patagonia (Argentina)

JUAN CORLEY; ANA JULIA PEREIRA; MAITÉ MASCIOCCHI

Guarujá

Congreso; International Union for the Study of Social Insects; 2018

International Union for the Study of Social Insects

In NW Patagonia (Argentina) two very similar non-native vespid wasps became established in the last decades. Vespula germanica was first detected over 30 years ago while V. vulgaris arrived some 20 years later. Invasion success-establishment and future spread- of either species may be influenced positively (biological meltdown) or negatively (biological resistance) by the degree of interaction with each other. We studied diet niche overlap among these predatory wasps, and explored long term species coexistence through a simple deterministic Lotka-Volterra competition model. The model was parametrized with site-specific field data on prey captured and current nest densities. Food items brought back to nests by workers were similar but there is some degree of segregation: the larger V. germanica can carry prey 3.3 times heavier and 1.6 times longer than V. vulgaris. Nest densities in shared locations, in turn where 3.12 and 4.7 nest/ha respectively. The model predicts stable co-existence of both wasp species in the invaded range, yet a higher abundance of V. vulgaris should be expected. Added to evidence on other foraging behavioral attributes of both vespids and invasion patterns observed in other regions, it is likely that the prior presence of V. germanica, does not contribute significantly to the biotic resistance of the invaded range for V. vulgaris.