Dr Rachael Horner of the Bioeconomy Science Institute was tasked with counting the tiny whitefly eggs Photo: Craig Robertson / Bioeconomy Science Institute
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In a small room in the Bioeconomy Science Institute in Lincoln, Dr Mark MacDougall refocuses a laser so that the beam is centred on a piece of metal tape on a tomato plant leaf. He's using it to detect miniscule motions.
The source of this movement? A tiny glasshouse whitefly on the underside of the leaf, trying to communicate in a type of insect language, one we can't sense or speak - a language of vibrations.
Biotremology
Before he started his PhD in this topic Mark hadn't heard of this vibrational language, the study of which is called biotremology. But the idea completely captivated him.
"I just had no idea that vibrations were just a part of the way that animals communicated. I had no idea that it was so widespread throughout the world and it was basically this entire world of communication that we humans are really not privy to."
Dr Mark MacDougall studies insect vibrational calls in the lab using a laser vibrometer. Photo: Craig Robertson / Bioeconomy Science Institute
Not only is it widespread but also varied. Insects can produce vibrations in all sorts of ways, like different musicians in a band, says Mark.
"Some of them will simply shake their bodies. Some insects will scrape little plates on the inside of their body, kind of like a grasshopper might. But they can also be used to send vibrations through a plant stem as well. Insects, like termites, will bang their heads on the ground to send vibrations throughout a nest."
And different patterns of vibrations are used to communicate different things. Which brings us to this room, isolated for sound and vibrations, where Mark is trying to record and translate the greenhouse whitefly language, with the hope of using the knowledge against them.
The problem with whitefly
Greenhouse whitefly is the most common whitefly species in New Zealand and can be found all year round in greenhouse crops. They have a preference for plants in the nightshade family, such as tomatoes, eggplants and capsicums as well as cucurbits like cucumbers and squash.
Adults are about 1.5 millimeters long and at different stages in their life cycle they feed on the plant sap, thereby weakening the plant and promoting the growth of sooty moulds. When conditions are right, they can reproduce in high numbers and put a lot of pressure on a crop.
Tomato-grower Pete Mundy knows this all too well. Based in the Heathcote Valley in Christchurch, Pete hydroponically grows different varieties of cherry tomatoes in a hectare-sized glasshouse.
Pete Mundy has allowed scientists to use his tomato-growing operation as a research trial site. Photo: Claire Concannon
Pete has his own methods of pest control to try keep the whitefly numbers in check, but he's also allowed researchers from the Bioeconomy Science Institute to run a series of biotremology research trials on some of the plants.
Because that's the whole point of the research, says project lead Dr Lloyd Stringer, to figure out if this vibrational language can be used to dissuade pest insects in a real life setting. And the trial, supported by industry groups Tomatoes New Zealand and Vegetables New Zealand Incorporated, helps with testing the practical limitations from the very beginning, he says.
"We could develop something here in the lab, for example, and go, 'oh, we've got a great idea, this will work'. Go to the glasshouse and go, 'oh heck, that's not going to work. We haven't got power plugs every 5 metres' or something like that. So... that helps us make sure that we're developing something that's going to be useful and applicable without too many tweaks."
Dr Lloyd Stringer, entomologist at the Bioeconomy Science Institute, is leading the research. Photo: Craig Robertson / Bioeconomy Science Institute
Telling pests to go away
The first trial in Pete's glasshouse started in October 2025 and used a single vibrational tone, previously identified by Japanese researchers as one that dissuaded the whitefly from laying eggs.
Mini-shakers were attached to metal beams in the glasshouse and vibrations were transmitted down the wires and to the plants every 15 minutes. The trial ran for six weeks, with entomologist Dr Rachael Horner counting the number of whitefly eggs on leaves from both control and treatment plants each week.
However, once they crunched the numbers, the team did not find a significant difference between control and vibration areas, although there seemed to be a slight trend for lower egg laying on the treatment plants.
There are a lot variables says Lloyd. For example, there was a large variation of whitefly numbers throughout the glasshouse, and at different times during the trial, which makes it hard to tease out effects. Plus, there are questions around how 'loud' the vibration needs to be for the whitefly to respond and how far the vibrations travel through the plants.
Greenhouse whitefly feed on plant sap, weakening plants and promoting the growth of sooty moulds. Photo: Craig Robertson / Bioeconomy Science Institute
In a follow up trial they will increase the frequency of the vibrations and they are also working with a Christchurch company to develop some bespoke devices which should increase the vibration area.
The idea of using biotremology to control pests is not new, but the practical problems and cost of producing the shaking needed in a growing environment have long been barriers to its use, says Dr Lloyd Stringer.
For growers like Pete Mundy, the promise of adding another non-chemical tool to the pest management toolbox is very attractive and for Dr Lloyd Stringer, the timing is right to properly trial it.
"The technology is getting there... we just need to do it now!".
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