Thursday, December 7, 2023

Distant experts fight bug threat

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Two scientists on opposite sides of the world are at the forefront of the battle to keep some of the most insidious, damaging pests at bay from valuable food crops. This summer in northern Italy they are working closely in an effort to try to stymie the spread of the voracious brown marmorated stink bug there and keep it out of New Zealand entirely. Richard Rennie spoke to Professors Claudio Ioriatti of Foundazione Edmund Mach and Max Suckling of New Zealand’s Plant and Food Research and University of Auckland about their battle with bugs across the hemispheres.
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Standing in an orchard in the warm north Italian sunshine Professor Max Suckling casts a rueful eye towards the mountains surrounding the Trento district.

“I am sure those hills are crawling with them,” he observes, referring to the brown marmorated stink bugs flitting and crawling across the ripening apples next to him.

The voracious bugs inject an enzyme making the fruit fall early, rot and become unsaleable before moving on to indifferently wreck the next ripening crop. 

Seconded to the Fondazione Edmund Mach research centre for the summer, Suckling is one of New Zealand’s leading experts on insect pests and control. 

This summer spent in the idyllic alpine setting in Trento brings him face to face with what he calls one of the most devastating, difficult pests he’s ever met.

The stink bug has already almost wiped out Italy’s €300 million pear industry and now threatens Trento’s 10,000 hectares of apple crops. 

Its impact in NZ would devastate the horticultural sector and significantly increase the amount of sprays used on remaining fruit, losing NZ fruit’s premium as a low-residue fruit supplier.

The bug’s spread from further north into the fruit bowl of Europe gives his work extra serious implications for both his Italian hosts and growers half a world away in NZ. 

Claudio Ioriatti is head of extension at the nearby Foundazione Edmund Mach Research Centre and an expert on the bug.

The two men share an acquaintance of over 25 years, moving from presenting at conferences around the world to a recognition they were following similar research paths at opposite ends of the world. 

That includes work on integrated pest management, combining biochemical and biological controls in a way that reduces reliance on pesticides in orchard and crop systems. 

“Over the years it was very reassuring to see the work Claudio was doing. It can be a pretty lonely path as a research scientist down at the bottom of the world. 

“Knowing Claudio has been working on similar areas has given me the confidence my ideas are worth pursuing. I often quote him, he often quotes me,” Suckling said.

Suckling oversaw the research response to the painted apple moth outbreak in Auckland in 1999, with a $65m eradication price tag, well under the $300m cost if it had become established. It was an effort that earned his team a science excellence award.

More recently a codling moth control programme he helped develop in Hawke’s Bay releases sterile male Canadian moths via drones. 

It has successfully knocked the moth population numbers back tenfold, ensuring orchards can use less spray and the industry retains valuable market premiums.

“Every country has issues,” Suckling says.

“Next month I will be visiting Chile, dealing with a moth incursion there. 

“There is no single solution and it often comes down to a combination of techniques, using pheromones, sterile males and other newer approaches.” 

Ioriatti oversees 150 staff in his extension role while traversing the globe working with cropping industries in countries grappling with pest incursions.

Biotremology, an emerging science with Ioriatti’s Fondazione at its centre, involves using synthesised insect mating calls to draw pests into traps. 

This pied piper technology uses mechanical engineering, insect science and high-tech equipment to record insect mating calls.

Early indications are it could play a key role in stopping the stink bug spreading further and be a critical monitoring tool in the early stages of an outbreak in NZ. 

A day spent with the men reveals they are in for a tough fight and not only with the stink bug. 

Italy is also grappling with the equally devastating spotted wing drosophila fruit fly in Tuscany and most other areas.

The fly damages high-value crops like cherries, grapes and blueberries and is likely to spread further as global temperatures climb.

Ioriatti is heartened by what he has seen achieved in NZ. Controlling pests like codling moth in Hawke’s Bay has provided some good pointers for the Italians’ work.

“There are lots of ideas coming out but getting funding for them, that is the hardest part,” he said.

Suckling says it is only when people’s food choices are limited because of pest impacts that the importance of the scientists’ work really hits home.

“And for some nations in sub-Saharan Africa that has already happened.  

“Their ability to grow high-value crops like mangoes is now non-existent due to insect incursions like the oriental fruit fly. With that goes an economic opportunity but also a dietary opportunity.

“They are left only capable of growing starch crops like cassava, which are not an ideal part of a diet. From there you have the risk of geopolitical impacts of hungry nations and displaced populations.

“The work we share with our Italian counterparts, it is really about taking a global approach to problems caused by globalisation,” Suckling said.

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