Foraging behaviour of the exotic wasp Vespula germanica (Hymenoptera: Vespidae) on a native caterpillar defoliator.

ANA LAURA PIETRANTUONO; SABRINA MOREYRA; MARIANA LOZADA

BULLETIN OF ENTOMOLOGICAL RESEARCH

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2018

0007-4853

Vespula germanica is a social wasp and an opportunistic predator. While foraging, these wasps learn and integrate different kinds of cues. They have successfully invaded many parts of the world, including native Nothofagus and Lophozonia forests located in the Andean-Patagonian region, where they forage on native arthropods. Perzelia arda, a lepidopteron defoliator of L. obliqua, uses the foliage to hide in and feed on. The purpose of this work is to study whether V. germanica use olfactory cues when foraging on P. arda. To do this, we used a Y-tube olfactometer and established three treatments to compare pairs of all combinations of stimuli (larvae, leaves with larval traces, and leaves without larval traces) and controls. Data were analysed via two developed models that analyse decisions made by V. germanica and allow to establishment of a scale of preferences between the stimuli. The analysis demonstrates that V. germanica choose P. arda as larval prey and are capable of discriminating between the offered stimuli (DIC null model = 873.97; DIC simple model = 84.5, n = 152). According to the preference scale, V. germanica preferred leaves with traces of larvae, suggesting its ability to associate these traces with the presence of the prey. This may be because, under natural conditions, larvae are never exposed outside their shelters of leaves and therefore use indirect signals. The presence of V. germanica foraging on P. arda showed the flexible foraging behaviour of this wasp; it may also act as a positive biological control, reducing lepidopteran populations.