Joint research project helps with wasp pest management

A joint research project between Victoria University of Wellington and the Department of Conservation is helping safely protect bees and native birds and insects from non-native wasp species.

The project, with Victoria University of Wellington’s Dr Rob Keyzers from the School of Chemical and Physical Sciences, students Ethan Woolly and Rose McClellan, and Eric Edwards from the Department of Conservation, involved testing the safety of bait being used against wasps.

A 2015 economic impact analysis estimated introduced wasps cost New Zealand’s economy more than $130 million a year with the biggest economic impacts on farming, beekeeping, horticulture, and forestry. The estimated direct costs to beekeepers from wasp attacks on bees was $8.8 million.

Beekeepers, the Department of Conservation, and other community groups often use a wasp bait called Vespex to manage wasp populations. Vespex is a protein-based bait that wasps eat and transport back to their nests, where they feed it to their larvae which digest and then share the food through the wasp colony, eliminating the entire nest.

Previous work has shown that the protein bait is attractive to wasps, but that honeybees, who prefer sweeter foods, will not consume it, says Mr Edwards. The joint research project aimed to test this conclusion and the evidence they gathered direct from hive colonies supported the idea that Vespex is safe for use around honeybees.

“To test the safety of Vespex, we developed a test to detect very small traces of fipronil, which is the key ingredient in the bait,” says Dr Keyzers. “We then tested 480 worker bee, bee larva, honey, and pollen samples from hives located near Vespex distribution sites over a period of two years.”

While no fipronil was found, a low level of a fipronil breakdown product was detected in initial testing of seven worker bees, but it wasn’t detected in two further tests of the same bee sample. The researchers concluded the derivative trace was likely just from a single bee and a rare occurrence given it wasn’t detected in follow up testing from the same sample or from any other hives sampled and it may not have come from Vespex wasp bait.

“Because no traces of fipronil were found in beehives, we can conclude that bees will not consume Vespex bait or be exposed to it in other ways and it is thus safe to use around honeybees to help manage wasp populations,” says Dr Keyzers.