It's common knowledge that our gut bacteria influence our health - and now Unitec researchers are finding specific gut bacteria may determine why certain species of insect damage New Zealand's lawns, pastures and vineyards.
The main culprit they're studying is a native scarab (Costelytra zealandica). In its larvae form, known as the New Zealand grass grub, it lives 5-10cm below the earth's surface and feeds on the roots of grassland and pasture, creating large, yellow dead areas. Adult beetles emerge from the soil each November and live for approximately a month, flying out to feed on fruit trees and shrubs.
Dr Marie-Caroline Lefort, a Unitec lecturer in environmental and animal science who's leading the project, says these beetles are also problematic in vineyards.
"When they emerge from the soil, adult beetles fly to the vines on the edges of a vineyard, and feed frantically on the leaves. If you don't have many leaves left on your vines, they won't produce fruit so well, and the plants may even die."
Some species might become pests due to the microbes that live in their gut, she explains. Most plants produce toxins to deter insects, but invasive species still manage to eat and digest the plants - and gut microbes are likely to be the key in this digestion process, by turning some of these otherwise toxic plant compounds into beneficial food for the insects.
Researchers are using molecular biology to compare the gut microbiome (all the genetic material of bacteria within a gut) of pest species with similar non-pest species, to identify an "invasiveness signature" - a group of gut bacteria that enable invasive species to digest and make the best of anything.
"We're getting close to pinpointing one group of bacteria that has been systematically identified in every sample of the pest species and not in the non-pest species," says Lefort.
"What is interesting about this gut bacteria is that in other studies, it's been found in different species of invasive beetles and termites too. It's strongly linked to the digestive capability of insects."
The project stems from Unitec's Applied Molecular Solutions (molecular biology) research focus area, which is dedicated to making a positive impact on New Zealand's physical environment and agritech sector.
The research group focuses on four main areas: biodiversity assessment; detection of pest species and pathogens, and diagnosing disease; studying the underlying genetic causes of disease and their spread; and the assessment of animal welfare.
Lefort and other Unitec researchers are working on this with collaborators from five other New Zealand institutions, as well as Poitiers University in France and the University of South Pacific in Fiji. Invasive species are a huge threat for small Pacific islands, she says.
"In places like these, people rely very much on their own agriculture, so if anything happens to the food they cultivate, they're in trouble. That's why we think it's very important to assess the risk and work towards early detection of invasive species. We try to create new tools to find ways to deal with invasive species, which could then be used by others."
When you're in the midst of the fiddly job of dissecting a grub's gut, or staring at lines of DNA coding that can make you go cross-eyed, it's satisfying to know the results of this research could improve how we manage and protect New Zealand's natural environment.
"Our aim is to develop knowledge that will help people target species in the areas we don't want them. We don't want to eradicate native insects, just control the size of the population and the damage they do in agricultural areas," Lefort says.
"If we find a specific group of bacteria that is systematically present in invasive species, other scientists could develop biological control strategies that would specifically target these bacteria, rather than the insect itself. We would 'remove' what makes the species invasive, so it won't be as successful, reducing the need for pesticides that also affect beneficial insects."