Identifying killer wasps’ victims
European paper wasps are getting the forensic treatment, with DNA analyses set to reveal their preferred victims.
Victoria University masters students Rose McGruddy and Matt Howse have returned to Nelson for a second year of study, measuring the abundance of European paper wasps and their effect on their surroundings, including DNA-testing wasp larvae and their stomach contents to find out what insects are falling prey to the newest wasp invader.
Paper wasps from Australia and Asia have been in New Zealand for many years but European paper wasps were first discovered in Nelson in 2015. They have established themselves in Nelson, and are slowly spreading across the country, so researchers are hoping to find out what places wasps are likely to be successful in, and what effect they will have on the places they invade. ‘‘We do not really know what they are doing in New Zealand, to our ecology,’’ McGruddy said.
‘‘They love people’s houses, fences, and garden furniture.’’
European paper wasps tend not to do well in forest or coastal areas, though coastal areas which have been recently planted can increase wasp numbers as protective cardboard or plastic sleeves around plants provide a shelter for a nest.
The pair first studied paper wasps in Nelson last summer and they said the abundance of wasps this year was significantly lower thanks to the colder, wetter summer and spring. ‘‘They are originally from the Mediterranean, so they prefer that hot, dry climate.’’
McGruddy said the wasps seemed to hunt purely on a ‘‘numbers game’’ system. ‘‘They just walk all over the plant until they touch a caterpillar ... they find food once, and then they ... keep coming back.’’
This is how paper wasps devastate monarch caterpillar populations.
Though monarch caterpillars are poisonous, all the toxins are in their skin, and the paper wasps are careful to only eat the insides.
Howse said the only current control method for paper wasps were overthe-counter fly-sprays, and it was important to get rid of nests when all the wasps were at the nest, as ‘‘any female can take over and keep the nest going’’.