Exciting Potential New Wasp Control Research
The newly discovered mite found on wasps in New Zealand. Image - Bob Brown
Wasps are now widespread throughout New Zealand and in some habitats they are one of the most common insects encountered.
In New Zealand, there are two introduced Vespula wasp species, the German wasp (V. germanica) and the common wasp (V. vulgaris). Despite arriving first, the German wasp is now outnumbered by the common wasp which is a stronger competitor.
The impacts of wasps on native biodiversity have been well studied in New Zealand, particularly in beech forest. Wasps not only take the nectar and honeydew resources that birds and other insects depend on, but are efficient predators as well. The arrival of wasps has also had social costs for New Zealanders, giving rise to human health issues and disrupting recreational activities such as gardening, walking or even having a simple picnic. The economic costs to primary industries such as apiculture, horticulture and viticulture have not been calculated but are considered to be significant.
Social insects such as wasps, bees, ants and termites are notoriously difficult to control. In a recent report, compiled for the Tasman District Council by Darren Ward, the options for improving wasp control were thoroughly investigated and summarised. The options ranged from manually destroying nests, using baits and attractants for chemical control, using pheromones to disrupt wasp behaviour, genetic manipulation (RNA interference) or using biocontrol agents to suppress the number of workers and reduce nest densities.
Biological control against wasps in New Zealand was attempted in the late 1980s using a parasitoid wasp (Sphecophaga vesparum vesparum) that lays its eggs on developing wasp larvae. Unfortunately they failed to build up large populations and provide adequate levels of control. Although there were other potential agents to explore, they were not considered to be sufficiently host-specific for release in New Zealand and the programme was discontinued. Landcare Research was therefore interested to hear recently about the serendipitous discovery of a seemingly devastating mite in wasp nests in New Zealand.
The mite was found a couple of years ago by Bob Brown, at the time a PhD student. Bob was working on the chemical ecology of wasps, as part of collaboration between Auckland University and Plant and Food Research at Lincoln. He was quite concerned when some wasp colonies he collected for his study started collapsing in the lab. When he examined the wasps under a microscope, he discovered they were heavily infested with mites. The mites turned out to be a species belonging to the genus Pneumolaelaps, which is normally associated with bumblebee nests rather than wasps. It is not known whether the mite is native to New Zealand or not, or how common or widespread it is.
Funding is now being sought to allow further investigations to be undertaken to determine the potential of this mite to be used as a biocontrol agent to control wasps. A newly formed community group V-BAG Vespula Biocontrol Action Group), will be applying to MPI’s Sustainable Farming Fund this month. V-BAG is based at the top of the South Island and currently includes mainly conservation and restoration volunteer groups, along with Nelson and Central Otago winegrowers. “Soon, we hope to have more industries (forestry, apiarists) and regions represented on the group,” said Ronny Groenteman, who has been busy drumming up support for the project.
“It is far too early to know how much potential this mite offers as a wasp biocontrol agent. We may discover that the mite is only a hitchhiker, or that it is damaging to beneficial insects or native insects. We may also find that it doesn’t transfer well between wasp nests in the field. These and other risks will be built into the funding application in the form of “stop–go” points, and if we discover the mites do not satisfy requirements, we will call the research off. We would then be keen to explore other potential agents in the wasps’ native range,” explained Ronny.
People interested in joining or supporting V-BAG should contact Ronny Groenteman or the group’s chairman, Bryce Buckland (bbuckland@xtra.co.nz).