Researchers from Auckland University say fewer wasps are found near forest cover with more near farms, weeds and plants.
A wasp approaches a honeydrew droplet from a scale insect. Photo: Richard Toft
PhD student and lead author of the study Julia Schmack said sunlight helped them to warm up and stay active, so areas shaded by canopy were not favourable for them whereas open areas of pasture land were.
Off the east coast of the North Island, 36 islands were tested using GPS technology to estimate wasp numbers for the study.
Researchers said wasps caused big problems for native and endangered species.
They compete for nectar and honeydew and are a particular problem in South Island beech forests where they consume large amounts of honeydew threatening the food source of native birds, bats, insects and lizards.
Wasps also eat native insects and drastically reduce the survival chances of native orb-web spiders.
There is one type of forest which is an exception to this study's findings - forest infested with high densities of native scale insects that produce honeydew.
"Also, the first plants that grow in areas where forest has been cut down are often exotic weeds and we think some of these may provide better food resources for invasive wasps than native plants," Schmack said.
She said the study provided new and important insights that may help control invasive wasps in New Zealand, particularly on offshore islands with endemic wildlife.
"If there were more forests, it would likely reduce wasp numbers. Re-planting with native trees is an obvious strategy to enhance habitat for native species.
"It's important to look at the whole ecosystem and the influence humans have on it to better understand invasive wasps."
The research team included scientists from the University of Auckland, Landcare Research Manaaki Whenua, and the Biodiversity and Climate Research Centre in Frankfurt, Germany and is published in Diversity and Distributions.