Rapid spread of BMSB calls for extra vigilanceBiosecurity
The rapid spread of the exotic pest Brown Marmorated Stink Bug across the northern hemisphere is putting unprecedented pressure on Australia’s biosecurity defences. While authorities work hard to keep this unwanted pest out, growers need to know what it looks like and be ready to respond if an outbreak occurs.
When you are next at a computer, take five minutes to watch a YouTube segment Stink Bug Hunters in Italy. It’s a short video, but it packs a pretty powerful punch.
As New Zealand Professor Max Suckling turns over the leaves of pears and kiwi fruit in Udine in northern Italy, ‘hunting’ is a major overstatement of what’s required. You don’t need to hunt for bugs that are swarming in the traps and up the trees, laying eggs under the leaves. They are everywhere.
“What damage have you seen here on different crops?” Max asks local Plant Health Service officer Iris Bernardinelli. “On pears, almost 100 per cent damage,” she replies.
100 per cent.
Meet the Brown Marmorated Stink Bug (BMSB: Halyomorpha halys). According to Australia’s Inspector General of Biosecurity Dr Helen Scott-Orr, efforts last year to keep this exotic pest out of Australia ‘stretched Australia’s border biosecurity system close to breaking point’. This year is expected to be worse.
Native to Asia, the BMSB is currently establishing itself as a serious horticultural pest across the globe, first appearing in the USA in the 1990s, in Europe in 2007 and more recently in Chile.
So severe was the impact of BMSB in Italy this season that growers abandoned affected crops and the country’s entire pear crop was declared at risk. Even under netting losses of 30-40 per cent were reported.
Robert Wiedmer, Technical Coordinator at the Northern Italy-based extension group Beratungsring, and a guest speaker at the Autumn Future Orchard walks here in April, told AFG that from a first detection in 2012 and first reported damage in 2014, BMSB had spread across the entire country, where it has no native predator, with the majority of the damage recorded in the northern fruit-growing regions.
“The bug is now found all over Italy,” he said. “The first damage was observed in Emilia Romagna in 2014, and since then the infested area has expanded every year and the damage has increased.”
BMSB feeds on just about any agricultural and horticultural crop you can think of with a host range of over 300 plants ranging from stone and pome fruit, cherries, tree nuts, citrus, berries, kiwifruit, tomatoes, capsicum and other vegetables to corn, soybeans, cereals and cotton and ornamentals.
In Italy Robert said pears had proved particularly attractive.
“This is why the damage to pears is particularly bad and has led to total crop losses in some cases this year,” he said. “The losses also depend very much on the location of the orchard. The damage to apple crops is lower.”
“The damage is currently being assessed; however, it can be assumed that several 100 million euros (100m Euro = AUD160m) in losses were incurred this year.”
Top 10 pest and rising
BMSB is yet to establish in Australia, where it currently sits at number 10 on the High Priority Pest list for apples and pears.
Biosecurity response consultant at research group cesar Dr Jessica Lye predicts that when the list is next revised BMSB will move up due to its rapid spread across North America and Europe, its wide host range, ability to wreak economic havoc and incredibly effective habit of hitchhiking all over the globe.
The risk to agriculture includes not only crop losses – which based on world-wide experience can run to 80 per cent – but also major challenges to Integrated Pest and Disease Management (IPDM) programs, possible market access issue sand the economic impact of any control zones and movement restrictions imposed in response to outbreaks.
In an interview with Good Fruit Grower magazine in March this year, Greg Krawczyk, entomologist at Pennsylvania State University’s Fruit Research and Extension Centre in Adams County said the use of broad-spectrum chemistry in response to BMSB in the US had wiped out natural predators of secondary pests such as woolly apple aphid, scales, mites and aphids, populations of which had then escalated and impacted crops as a result.
“We really messed up the whole integrated pest management system we had before,” he said.
As well as being an agricultural pest, BMSB is also a major public nuisance pest, seeking shelter in homes and buildings, vehicles and sheds, often in large numbers, where, true to its name, it produces a foul smell if crushed or disturbed. If once established in cities and towns, experts argue it will be near impossible to eradicate.
Holding back a rising tide
The 2019-20 high risk season kicked off on 1 September and runs to 31 May, a period which coincides with the north hemisphere winter months in which BMSB hibernates.
So far this year there have been 54 detections of the pest and in early December a ship carrying 3500 cars and heavy machinery was turned back after bugs were found aboard.
The numbers of BMSB reaching Australian borders have been steadily rising since it was first detected here in large numbers in 2014-15 in vehicles and machinery shipped from the United States. It is inevitable that some bugs will sneak through.
BMSB has been detected post-border in WA, QLD, Vic and NSW on three occasions in 2017-18 and eight in 2018-2019, triggering prompt eradication responses by State Governments. The bug has also been found in SA hiding in imported goods and picked up by border controls in Tasmania. As weather warms up Victoria and WA have ongoing surveillance around detection sites from last season to confirm all bugs have been eradicated.
Compounding the challenge of the rising BMSB population is the seasonal behaviour of this bug which effectively means it goes into hiding and hitchhikes around the globe. A voracious feeder during the warmer months, it clusters and hibernates in large numbers during the cooler months. sheltering in out of the way places.
Electrical equipment, bricks, agricultural machinery and parts, a mini bulldozer, shrink-wrap terracotta pots, household goods and furniture, air conditioning brackets, pumps, lawnmowers, computers, books and personal items shipped by sea and by air are just some of the places these bugs have been found.
On arrival at Australian shores, bugs emerge from hibernation, hungry and ready to seek out food.
The Australian Government declared the USA a target-risk country for BMSB after the 2014-15 season. Italy was added in 2017-18 as detections on goods from Europe increased. France, Georgia, Germany, Greece, Hungary, Romania and Russia joined the list for 2018–19, a season which saw a near doubling in live interceptions (Figure 1) and the turnback of two ships after live bugs were discovered on board.
This season there are 32 countries categorized as target risk including the United States, most of Europe and Canada. A 33rd, Japan, is subject to heightened vessel surveillance only.
The Australian Government, working with the New Zealand Government, has significantly ramped up risk management measures for this season targeting cargo imports from high risk countries. Detector dogs have been trained in Australia to detect BMSB in high risk imported machinery, with other measures including mandatory offshore fumigation, onshore treatment and random pest inspections. Vessels with goods deemed high risk that turn up untreated, or on which bugs are found, will – as in the case of car and machinery cargo ship in December – simply be turned away.
Government and industry are also engaged in ongoing risk analysis and research into new ways to respond to, detect and manage the threat posed by the global expansion of BMSB.
What can growers do?
Arguably the most important action growers can take is simply to be aware of the risk, what the bug looks like and what to do if you spot it – contain it and contact the Australian Exotic Plant Pest Hotline on 1800 084 881.
The high-risk period runs until May and females emerging from hibernation can deposit eggs within two weeks.
Growers should be particularly cautious if they have imported machinery from overseas or used shipping containers direct from port, and consider keeping tracking information for reference if an incursion does occur.
A big challenge for Australian growers is that there are a large number of Australian native stink bugs which are similar to BMSB, and cause similar damage to fruit. It is important to know what you are looking for, but not to be alarmed until absolute identification has been established.
The adult has a brown ‘shield’-shaped body, the colour of which varies but is generally mottled with a reddish tinge. It can be distinguished from native stink bugs by the distinctive white banding on its antennae and the outer edge of its body.
Eggs are laid in clusters of 25 to 30 on the underside of leaves. They are light green to white in colour, and barrel shaped.
There are very good identification guides – for both BMSB and native stink bugs – available for download online (see resource links below). Print them out and pin them in a prominent place with the Exotic Plant Pest Hotline 1800 084 881.
Damage can appear as necrotic spots, dimpling and brown corky spots in the flesh which can be mistaken for calcium disorder.
“There is ongoing work overseas to better understand what these salivary toxins are doing,” Jess Lye explains. “When it is feeding it essentially liquifies the surrounding tissue.
“Someone might notice the pierce holes, or you might see the bug clustering on apples, but it is the brown corking that is really noticeable when you cut into the fruit, as well as sunken areas on the skin.”
Note: native stink bugs cause similar damage, so it may be necessary to catch the pest to be sure which is responsible.
“It is how we respond and approach these challenges that make Australian farmers leaders in IPDM” – Elizabeth Mace
Practise orchard hygiene
Practise good on-farm biosecurity. Don’t just let anyone into your orchard. Check your property, equipment, vehicles and crops regularly for BMSB and other unusual plant pests and diseases. If you receive a container of equipment, or a package from overseas, consider the risk and inspect it.
In spring, summer and potentially autumn, BMSB will seek out ripe/ripening fruit to feed on, aggregating on leaves and fruit. BMSB prefer edges of crops and orchards, so focus on these areas when conducting visual surveillance. Most damage occurs in early summer, but may only become noticeable coming into harvest.
BMSB have been found to be particularly attracted to ornamentals including Tree of Heaven (Ailanthus altissima), Princess tree (Paulownia tomentose), Magnolia and Chinese pistachio, so if you have these trees, keep an eye on them also.
Check under leaves for juveniles and eggs. Adults are attracted to light, so check around any outdoor lighting in the evening. Note that this pest is very sensitive to movement and will drop to the ground when disturbed. Regular visual surveillance appears to be the most effective approach to finding this pest.
Set up surveillance
Logistic centres, packhouses and areas close to businesses that handle a high volume of goods from overseas may wish to take the precaution of monitoring during the high risk season. There are a number of lures and sticky or pyramid traps available from overseas companies online – Trece, AgBio and Alpha Scents – though growers need to be aware prices and effectiveness varies.
The APVMA has approved six permits for use of lures and further details are available on the APAL and APVMA websites.
The WA Department of Primary Industries and Regional Development has a simple online video and fact sheet on making a home-made light trap for BMSB.
BMSB-free, a status worth preserving
If BMSB does get in and cannot be eradicated, growers, like their overseas counterparts, will find ways of managing it. At the extreme end the hazelnut-growing South Caucasus state of Abkhazia encourages the public to catch them by hand, offering a bounty of 1000 rubles (AUD $22) per kilogram of bugs – in the first year they collected five tonnes.
Ten years after BMSB became established in the USA, growers say they are learning to manage the bug with monitoring and threshold spraying, alongside biological controls and attract-and-kill strategies.
Pest and disease technician Elizabeth Mace of Goulburn Valley-based GV Crop Protection said Australian growers are already managing native pests, such as the harlequin beetle, that exhibit similar behaviour to BMSB.
““It is not as scary as it seems,” she said. “There are practical solutions available, such as vigilance, weed management and spot spraying. There are always challenges in farming, it is how we respond and approach these challenges that make Australian farmers leaders in IPDM solutions.
“But chemistry is a fall-back strategy.
“Surveillance and prevention is the best outcome.”
Which bug is that? Identification of BMSB
The Biosecurity Portal – portal.biosecurityportal.org.au – has BMSB resources linked from its home page including DAWR’s identification guide, which covers other similar bugs.
Information, fact sheets, and videos on BMSB are available via a quick link on Agriculture Victoria’s website agriculture.vic.gov.au
Protect your farm
The National pest & disease outbreaks site – outbreak.gov.au – has information about BMSB and current responses.