SHARPSHOOTERS
BUG vs BUG A
s Director of Emergency Management in New South Wales, Dr Leigh Pilkington is on the lookout for a mottled brown leafhopper with transparent wings and bulging eyes. There are ivory spots running along its abdomen, and like the fleas that spread bubonic plague throughout the world, in its mouth it carries doom. People aren’t at risk: only plants. Ones that bear grapes, citrus, and olives are particularly susceptible though numerous others have fallen prey. Out of over 600 invasive plant pests threatening the country, the glassy winged sharpshooter, Homalodisca vitripennis, ranks in the top 10, poised as it is to destroy Australia’s vineyards one grapevine at a time. Of the 175 plant species that sharpshooters are keen to feed on, including eucalypt types, all but one grow in Australia. “If it arrives with the pathogen Xylella fastidiosa then it’s going to be a massive problem,” Pilkington says. X. fastidiosa reigns supreme as number one among all biosecurity threats to Australia’s agricultural crops. It’s a lethal bacterium that lives in the mouths of sharpshooters, infecting and killing the plants they eat. A living sharpshooter hasn’t been discovered in Australia yet, though dead ones turn up occasionally in the cargo hold of airplanes landing here. If someone stumbles upon a live insect resembling this highly mobile harbinger of 84 COSMOS MAGAZINE
viniculture ruin, it must be reported within 24 hours by calling the Exotic Plant Pest Hotline at 1800 084 881, which triggers a series of defensive measures that play out in rapid succession. The suspicious bug will be rushed to the premier testing facility in Camden, south of Sydney, for species identification. A male is required for the definitive ID test: the genitalia is macerated, and the soft connective tissue peeled away so its unique genital structures can be compared to anatomical sketches. Meanwhile, Pilkington’s biosecurity team in the NSW Department of Primary Industries will coordinate with the Commonwealth to quarantine the place where the leafhopper was found and conduct intense surveillance of surrounding areas. Technically known as delimiting surveys, this protocol aims to contain the invasive plant pests while attempts are made to eradicate it. During such emergencies, Pilkington says, “To catch things, you got to be quick, and you got to be decisive, and you don’t muck around.” That’s because there are great savings for Australia if we stomp out plant, animal, or microbial invaders before they establish themselves, and Pilkington refers to what is called the biosecurity continuum as a visualisation of the adage: an ounce of prevention is worth a pound of cure. But if the sharpshooter isn’t caught before it infests a vineyard, a tree nursery, or any place where irrigation fosters leafy growth, then the only
RIGHT: BRETT DAVIES, PHOTOSIGHTFACES / GETTY IMAGES
Australia is braced for invasion by the glassy winged sharpshooter, but happily much of the science needed to control the damaging leafhopper is already done, writes Martin J Kernan.
