Key points
- Weevils are fussy eaters, making them ideal biocontrol warriors against invasive weeds.
- Dung beetles recycle nutrients by rolling or tunnelling dung, reducing flies and improving soil health.
- Lady beetles and parasitic wasps help protect canola from pests, reducing the need for pesticides.
Choosing your fighter can be tough when there are so many great options. Do you prioritise a cool look, armour, speed, strength, savage taunts, hunger to hunt or advanced combos?
It all comes down to the opponent you’re looking to defeat or the terrain you need to navigate.
Let’s take a look at some of the small and mighty defenders making a big impact protecting our crops from pests, waging a war on weeds and dealing with a whole lot of crap!
Weevils waging war on weeds
Weevils are ahead by a nose when it comes to choosing a biocontrol warrior. They’re naturally fussy eaters so they can make great biocontrol besties to tackle weeds. Their long snout, or rostrum, gives them underwater breathing superpowers and an unmistakable appearance. They use this to drill into plant tissues to feed or lay eggs.
Weevils are actually a type of beetle. There are close to 200,000 species of weevils in the world. But only about 62,000 have scientific names so far. Some of our biocontrol weevil geniuses include the Cabomba weed weevil and the Paterson’s curse weevil.
Dung beetles dung good
Beginning in the 1960s, CSIRO has introduced 44 dung beetle species from overseas.
Dung beetles have specialised gut microbiome bacteria. This helps them break down the cellulose in the dung and access the amino acids they need to grow. They come with two different battle plans: rolling or tunnelling. Either way their superpower is recycling.
Tunnellers dig down below the cow pats and pull pieces of dung underground. They pack these into tunnels and chambers. They then lay their eggs in the sausage or pear-shaped dung mass. In contrast, rollers shape pieces of dung into round balls and roll them away from the cowpat. They do this to ensure their own piece of dung real estate, laying their eggs inside the ball and burying it to keep it safe.
Whether they're rolling or tunnelling, dung beetles use their big engineering energy and commitment to cleaning up to return nutrients from the sloppy dung of livestock to the soil. Our native dung beetles can’t do this as efficiently as they’re focussed on the hard, dry droppings of our native species.
Dung pads are also breeding sites for bushflies. So, removing them from the soil surface helps reduce fly numbers.
Canola allies
When you’re a crop like canola facing attack from 30 different species of invertebrate pests, you need you a Marvel-esque team of winged and crawling crusaders for protection. If unchecked, it's estimated these hungry invaders would cause $54 million of crop damage annually.
But a crew of canola allies can be coaxed into combating the pests. Getting the team balance right can stop infestations escalating, reducing the need for powerful pesticide campaigns to control outbreaks. Conserving the agricultural management relies on diversity to provide protection throughout the crop growing stages and the seasons.
Lady beetles are aphid assassins
Despite the fashionable armour, the lady beetle is a polka-dot assassin. This femme-fatale has a voracious hunger for sap-sucking aphids, consuming around 1000 aphids during their lifetime. Their palate also extends to mites, mealybugs and scale bugs.
Their hunger is not their only superpower. They can also multiply rapidly to control infestation. Laying their eggs among an aphid smorgasbord, the alligator-like larvae hatch with a predatory instinct and a single-minded mission to eat. One ladybeetle larva can consume 350 to 400 aphids!
Caterpillar killing wasps
The braconid parasitic wasp is a predator with a nursery plan straight out of a horror movie. They use the egg and adult stages of other pest insects as hosts for their young. Adopting a truly gruesome parenting strategy, they lay their eggs in or on their victim (oviposit). This provides their larvae with a ready meal when they hatch, killing the reluctant host.
These small to medium-sized wasps with narrow waists, long antennae, and ant-like heads are found throughout Australia. They are excellent and effective biocontrol agents against many insect groups, including aphids, caterpillars and beetle larvae.
Encouraging beneficial insect patrols
These are just a few examples of beneficial insects. Effective crop-wide pest management relies on diversity to provide protection throughout the crop growing stages and the seasons.
Our researchers are looking at ways to encourage beneficial insect, mite and spider armies to flourish. We are studying the ecology of beneficial species in canola growing regions, to understand their impact on key canola pests, and determine ways to enhance their activities to control pests. Alongside research partners*, we are developing tools to help growers integrating beneficials into their pest management practices and reduce pesticide use.
Whether you’re an avid gardener or a broadacre agriculturist, getting to know your allies is key to telling the goodies from the baddies and supporting their survival.
Beneficial insects are our natural invertebrate allies. It’s impossible to choose just one as the ultimate fighter. Together they make a great team of insect icons helping our agriculture and environment.
*Canola Allies project: Tailoring Practices for Beneficials in Canola Systems (2023-2028). GRDC Investment CSP2309-004RTX Minimising damage of invertebrate pests in canola through a better understanding of the impact of beneficial insects. A collaborative research project led by CSIRO, in partnership with NSW DPIRD, SARDI, Murdoch University, DPIRD and Biological Services.