Tasmanian Institute of Agriculture researchers think more mites could help growers get more blackberries to market

So how do you stop these micro monsters in their tracks? 

Researchers think that increasing the number of predatory mites might be the answer. 

The Tasmanian Institute of Agriculture (TIA) is working with commercial blackberry growers across Victoria and Tasmania this season to measure the effectiveness of two different predatory mites, Typhlodromus occidentalis and Typhlodromalus lailae.

TIA Researcher Dr Stephen Quarrell said T. occidentalis—affectionately called ‘Occi’—is a seasoned veteran when it comes to protecting crops.

“Occi has been around for quite some time and is regarded as an efficient predator.  It’s more tolerant of a broader range of environments than some other predatory mites and fairly hardy when it comes to pesticide tolerance.” 

In contrast, T. laliae is the untested rookie with something to prove. Dr Paul Horne, a researcher from IPM Technologies, notes that T. laliae is a good bet for tackling redberry mite.

“This mite is naturally found in the cooler southern half of Australia, making it more likely to survive in these climates. It is known to feed on broad mite, which comes from the same family as redberry mite,” Dr Horne said.

READ MORE: From the Tasmanian Institute of Agriculture

Predatory mites were identified as a potential pest management solution after TIA surveyed crops last year in the early stages of the project. Though some predatory mites were found, the populations were unbalanced.

“We found that predator numbers in commercial blackberry crops were extremely low relative to the number of redberry mites. This means we may need to tip the balance in favour of predators by supplementing the natural population with some commercially reared predators," Dr Quarrell said.

So how many mites is the magical number?

“For every ten broad mites you need one predatory mite to effectively manage the pest. This is a good guide as to the ratio we are likely to need to manage redberry mite,” Dr Quarrell said.

Growers may be unknowingly giving redberry mites the edge over their hungry cousins, however. While pesticides are often necessary in intensive berry production and can be a useful tool in pest management, it’s important to minimise unwanted impact on potentially helpful predators. 

“Fungicides can often catch growers out as they don’t necessarily see these as being harmful to mites and predators.

“Switching to registered fungicides that have low toxicity to predatory mites can help tip the balance in favour of predators,” Dr Quarrell said.

TIA will closely monitor the fate of both the predatory and redberry mites in blackberry crops through both winter and the cropping season. Rather than blanket treatment of harmful pests, it’s hoped that caring for predators may be a boon for the future sustainability of intensive blackberry production.

Additional information on TIA’s ongoing redberry mite project is available at http://bit.ly/redberrymite

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