One of the most unforgettable scenes in science fiction history in the classic 1979 horror movie Alien was inspired by a small wasp - and now the wasp may be about to play a starring role of its own.
Scientists at Plant & Food Research are studying parasitoid wasps to determine whether they can save growers millions of dollars a year by biologically controlling insect pests.
In the movie - it won the Academy Award for Best Visual Effects - an alien burst from the chest of the film's star John Hurt, an act that mimicks how parasitoid wasps feed on other insects.
The female wasp works her magic by using a needle-like organ (ovipositor) to lay eggs on or inside her host. When they hatch the larvae feed on, and eventually kill, the host emerging in search of a new host for the next generation.
Plant & Food Research entomologist Dr Gonzalo Avila says using nature to battle nature in this way is an increasingly desirable pest control option, for both consumers and growers, as it reduces chemical pesticides in the food chain and the environment.
One of these wasps, known as Mastrus ridens is already helping control codling moths in apples (it lays its eggs in the cocoon of the moth) and has been deployed in apple orchards since 2012.
Watch video of the female Mastrus wasp laying her eggs here:
Codling moth caterpillars cause massive problems for apple growers. By boring into apples, they affect the quality of the fruit and cost millions of dollars a year to control. The presence of one codling moth in an export shipment can determine whether countries accept our apples for an entire season.
"Consumers don't want caterpillars in their fruit, but they also don't want residues from pesticides," Avila says. "It's a delicate balance for growers everywhere. Fortunately, nature has a way of controlling some of the insects that travel to New Zealand, we just have to find the best way of using that to our advantage."
Avila is looking at how Aotearoa New Zealand could control the Brown Marmorated Stink Bug (BMSB) - a highly damaging pest that is making its way around the globe (although a population hasn't been detected here yet) - by using another parasitoid wasp, the Samurai wasp.
BMSB not only feeds on crops, but also nests in any sheltered spot over winter, whether in farm buildings, factories, houses, or cars. The Samurai wasp deposits its eggs in the eggs of the bug, killing the BMSB before they can hatch.
"We want to be ready to fight BMSB, as it has proven to be highly destructive to agriculture in other countries, and a social nuisance. Having the Samurai wasp ready to deploy is one crucial weapon in our armoury as we prepare for a potential invasion," says Avila.
Most natural enemies of insect pests originate from the pest's home territory – in the case of BMSB, both the bug and the Samurai wasp are natives of eastern Asia. So, before they can be deployed in Aotearoa, extensive research is undertaken to make sure the remedy isn't as dangerous as the pest itself.
"Bringing any new organism into New Zealand has to be done with care," says Avila. "The last thing we want to do is release an insect to defeat a pest and have it decimate our native flora and fauna in the process."
Plant & Food Research is also looking at sex as a solution for insect pest control. The chemicals animals exude when looking for a mate, sex pheromones, are a tried and tested way of controlling insect populations by confusing and distracting the males.
"Pheromones are a really good way of disrupting pest populations," says Nicola Mauchline, also an entomologist at Plant & Food Research. "Pheromones don't affect anything other than the target insect, and they leave no residues.
"But by filling the orchard with the female odour of an insect species, the males cannot detect and locate an individual female to mate with. No mating means no offspring, so the population quickly collapses."
Plant & Food Research scientists have identified the sex pheromones of a number of insect pests and created synthetic versions in the lab. These are now being produced in industrial volumes by global company UPL and sold as mating disruption dispensers under the Isomate brand.
The latest of these, developed by Mauchline and her team, was launched last year to help avocado growers reduce fruit damage from leafrollers, a family of insects which can lead to significant fruit loss and control costs if not managed.
Pheromones can also be used as lures, enticing insects into traps so growers can monitor insect populations and make decisions on what control methods are required (or if there are any insects around that warrant action at all).
Plant & Food Research are also looking at whether these pheromones could be combined with insecticide baits, literally luring insects to their death.
Mauchline says there isn't one magic bullet for controlling any pest, so creating a toolbox of different methods means growers can use the techniques that work in their own situation.
"Gone are the days of diarised spraying," she says. "The modern grower has a sophisticated system of responding to pest numbers when they reach a specified level - and using natural biological controls to reduce numbers before reaching for the pesticide as a last resort."
