Italian expert praises NZ stink bug approach

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A visiting Italian biosecurity expert has praised New Zealand’s efforts to deal with a stink bug incursion before it happens, putting this country “on another planet” to his homeland.

Professor Claudio Ioriatti, from the Italian agricultural and horticultural research centre Fondazione Edmund Mach in Torino, recently visited Tauranga as part of an AgMARDT (Agricultural and Marketing Research and Development Trust) sponsored trip.

Ioriatti has worked closely with Plant and Food Research staff for 25 years on both countries’ mutual biosecurity issues.

The professor said the brown marmorated stink bug was the worst insect incursion northern Italy has experienced in recent years – and this in a country that has averaged two new alien species a year for the past 20 years.

It first appeared in significant numbers in 2012, with the region’s plentiful and productive orchards providing a varied food source to thrive, while dwellings offer over-wintering habitat.

“The estimated cost now to orchardists and growers in my region Trentino is 150 million Euro a year, so you can understand why growers want to control it.”

Ministry for Primary Industries estimates are that a stink bug incursion into New Zealand could cost this country $4.2 billion in lost earnings by 2030.

To date only isolated numbers of the bugs have been detected.

It means when – rather than if – the bug arrives you are in a very good position to deal to it.

– Claudio Ioriatti

In Italy chemical controls for the bug are limited to only two spray options, and these can only be applied in minimal amounts due to fruit retailer restrictions on spray use.

Ioriatti said the silver lining of the bug’s presence was that it moved into urban dwellings over winter, drawing broader attention to its presence, and with that the community desire to do something about its control.

He and his colleagues have developed a smartphone app for people to report bug infestations, including taking a photo and loading in location data to make tracking incursions in real time possible.

Pheromone traps have proven relatively poor at trapping the bugs.

Most orchards now have to be draped in protective netting, proven to be the most effective means of keeping the bugs out as they migrate back to ripening fruit over late spring-summer.

But orchardists are also conscious they operate in a heavily touristic environment, where perceptions of Italian countryside do not always accommodate unsightly artificial netting.

“We are selling our landscape to five million visitors a year here. Tourism is 15 percent of our region’s income, so using the netting is really something we would like to avoid.”

The challenge to researchers like Ioriatti is compounded by Italian laws that prevent the introduction of a non-native species to control an embedded pest like the stink bug.

New Zealand authorities have approved the introduction of a known stink bug parasite, the Samurai wasp, which can be released immediately should a stink bug outbreak occur here.

“It means when – rather than if – the bug arrives you are in a very good position to deal to it,” he said.

“We are required to find a native enemy in Italy and have a parasite species, but unfortunately the parasitism rate is only 17 percent – it’s too low.”

Researchers are studying their options, which also include the use of Sterile Insect Technique. This involves releasing overwhelming numbers of sterile male insects into the wild to mate with females, with no offspring produced.

“This is a potential tool for us as we await the opportunity [to introduce]the right parasite.”

Ioriatti said he was deeply impressed by the level of biosecurity awareness projects like the Better Border Biosecurity project launched in Tauranga has brought, and the ability of policymakers, communities and scientists to work together on biosecurity issues.

“Sooner or later the stink bug will arrive here, but you can use this time you have to take a sustainable approach to deal with the incursion.”

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