Brown marmorated stink bugs
A summary of some points that may affect summerfruit growers
Earlier this month, Richard Mills attended a Symposium on the brown marmorated stink bug (BMSB) in Napier and wrote the following report.
An all-day symposium on one insect that is not even in the country might seem a bit over the top, but this was a great opportunity for the science community to share what they are working on and to draw on the experience of people working in the USA, Italy, and Chile. It was also a good chance for me to come up to speed on the summerfruit industry’s behalf and indulge my inner geek.
BMSB are intercepted at the New Zealand border every year. A seasonal surveillance programme is in place to try and detect BMSB if they arrive, and monitoring is conducted using pheromone traps in conjunction with herbage inspections around the traps. We’ll come back to the herbage inspections in a bit. There are now two dogs trained for the detection of BMSB as well. Other types of sensors are being developed, as are potentially improved versions of the physical traps.
Should BMSB become established here it seems as though stone fruit (peaches were mentioned specifically) are a preferred host. Fifty percent damage has been reported in USA peach orchards and 30-50% damage in kiwifruit orchards. Offshore research is being funded by a number of industry parties, and what works for them may well apply to us.
It seems as though much of New Zealand would be climatically suitable for BMSB and that hot rather than cold would be the limiting factor. Some USA observations suggest that northern Florida is suitable but not so southern Florida. BMSB is found in Canadian production areas.
While an established population would be really serious for fruit and vegetable production, we think there would be a chance to gain some control. BMSB is a landscape-wide pest with potential to affect almost all fruits, possibly including native plant species.
So, what could we do if a population was to become established, and it was deemed that control rather than elimination, was the reasonable response? The good news is that the options are being worked on now, and we have the experience of the likes of the USA, Italy, and Chile to draw from. There will be no silver bullet to control this pest, and any chemical response would likely involve hard chemistry that will set our IFP technology back decades. Apples have pretty much achieved residue free fruit and summerfruit would like to be there soon, but, up to six applications of something like Mavrik is not the direction of travel that we desire.
The ideas and technologies that are being worked on include:
- Lure and kill traps. Shane Max from Zespri showed us a video of the traps being used in Italy which seemed to be luring BMSB to the vicinity of the traps but not so much into the traps. Hence the need for inspections around the traps as mentioned above. At this stage these would seem less effective than what we can achieve with Carpophilus lure and kill traps in Hawke’s Bay. More work needed.
- There are monitoring sticky traps similar to what we already know, and ‘ghost traps’ with insecticide impregnated netting used offshore. At this stage of development these seem to be more useful as a monitoring tool as we use for Codling moth and leafrollers.
- Exclusion netting. They talk about five-sided, much like we do to keep birds off cherries, but more than the standard netting used in kiwifruit. The trick seems to be 2mm squares as the small nymph stages need to be kept out.
- Sterile insect technique (SIT) is being worked on. This has some theoretical potential although it would involve going through approvals and releasing feeding stage insects which is not ideal. A little different to releasing sterile moths in apple orchards which are not at the larval feeding stage.
- Bio-control seems to be an important part of the potential control mix. The BMSB Council has gained approval to import a wasp that predates BMSB egg clusters called Trissolcus japonicus or Samurai wasp, which is only permitted should New Zealand have a BMSB incursion. As yet we are not sure of its ability to disperse in the environment, and the preliminary dispersal trials in the USA were not that encouraging. Other, complementary bio-control agents are being looked at.
- Insect growth regulators. This is technology that summerfruit growers are already familiar with. The human and environmental risks are low with this type of product but there is work to do yet on finding an effective product.
- Chemical control. Telstar (bifenthrin an SP) is a chemical that is registered in New Zealand but has no stone fruit label. Other chemicals mentioned include Actara (Thiamethoxam which is a neonicotinoid) and Starkle (dinotefuran, also a neonic). We are trying to find alternatives for all of these product types for use in stone fruit right now. Another that was mentioned was tau-fluvinate or Mavrik.
- Trap crops such as maize and soya beans have been suggested as these could be preferred hosts. The drawback being that when these crops are harvested the BMSB moves onto other hosts such as stone fruit trees.
- Phenological modelling. USA work has suggested that 100 DD14 is when BMSB will start moving from the wilder environment onto peach trees. This could be nice-to-know if we need to move to long-term control.
So, what might a bit of medium-term planning look like if I was a cherry grower in New Zealand? The more intensive orchards that are netted might look to replace the side netting when the time comes with a version that will keep out stink bugs. Apparently, the top of the cage is less important as fewer bugs go up and over.
The use of trap crops around the orchard is worth a thought. Maize is a preferred host, grows well in Hawke’s Bay and summerfruit is well and truly picked and gone by maize harvest time. Whether the maize is harvested and sold, or sprayed with heavy duty insecticides needs some thought. What a Central Otago trap crop might be I’m not sure, but it can’t be too difficult.
But if my crop is not netted, or there is not enough value to cover the fruit, what then? Perhaps the maize or trap crop becomes even more important, like a no-net netting. Insecticides would more likely be a key part of control, perhaps in the maize and the first row or two of peaches and lots of monitoring to know when the movements start and where they are coming from. We will need to learn where the alternative hosts in the neighborhood are and how BMSB on them might be controlled.
We are fortunate in that BMSB is not yet here in New Zealand, that we have the experience of overseas growers and scientists to draw on, that there is a big team in New Zealand working on control measures, and that border security to this point in time has done its job.
A note on the biosecurity levy
Our Biosecurity (Readiness and Response—Summerfruit Levy) Order 2019 came into force on 1 November 2019. At the 2020 AGM summerfruit growers voted in favour of setting the biosecurity levy rate at 0.05%. This is the first time the biosecurity levy has been implemented and will allow Summerfruit NZ to collect the necessary funds to face any future biosecurity incursions affecting our industry. While we did have limited reserves available to cover biosecurity responses, unfortunately in the case of fruit fly, these responses have become increasingly frequent and can no longer be sustained in the same way.
Exotic pest incursions can disrupt orchard operations, lead to market access restrictions and impact on fruit production and quality. The best scenario is early detection which gives us the best chance of eradication. However, eradication is not always possible and being prepared to effectively manage a high impact exotic pest is important for production and export continuity.
This is the work that Summerfruit NZ supports as a partner to the GIA on behalf of growers. This work involve minimum commitments, which include participation on the decision making and sharing the cost of readiness and response activities with government and other industries.
In general terms, the biosecurity levy can be activated for any of the following three reasons:
- in the event of a biosecurity response to meet our industry share for the cost of the response
- to establish a biosecurity reserve fund
- when multiple Operational Agreements are signed and additional funding is required to meet the industry’s share of readiness costs.
Any changes to the levy rate are to be discussed at an AGM.
Biosecurity business pledge
Summerfruit NZ has taken the biosecurity business pledge under ‘This Is Us’, the biosecurity brand formed as part of the Biosecurity 2025 programme. The biosecurity pledge was launched on 31 October 2019 by the Hon Damien O’Connor, Minister for Biosecurity and MPI officials.
Under this pledge, Summerfruit NZ is committed to playing our part as a support organisation in the efforts to prevent pests and diseases from getting into New Zealand or helping to stop the spread if they arrive our country. Our pledge is to be an active part of New Zealand’s biosecurity team of all New Zealanders by integrating proactive biosecurity practices into our operations and supply chain.
Photo: Biosecurity and export manager Juan Rosales signs the pledge on behalf of Summerfruit NZ while the Minister looks on.
Brown marmorated stink bug and spotted wing drosophila workshop
In the last week of May, Plant & Food Research hosted a meeting open to Hawke’s Bay apple, wine grape and summerfruit growers on two very important pests that challenge New Zealand’s border biosecurity systems. These pests are the brown marmorated stink bug (BMSB) and spotted wing drosophila (SWD).
Presenters included speakers with international experience in the management of these pests:
Dr Claudio Ioriatti from Italy and Dr David Bellamy from the USA – now based in New Zealand. Along with the international speakers there were also presentations from recognised specialists from PFR and MPI.
The meeting was an important opportunity to learn more about these biosecurity threats not currently present in New Zealand, how they are being managed overseas and what work is being done to minimise the impact these pests may pose on our horticultural industries.
Below is a summary of the main points from the meeting.
Brown marmorated stink bug
MPI readiness for BMSB
- Taking a seasonal approach to pre-border inspection.
- 61 live BMSB have been found this season, often within luggage.
- Two detector dogs currently with more being trained.
- Traps are reported to have an attractant range radius of 124m or about four hectares.
- Chemical control is difficult; only Bifenthrin is available which is a synthetic pyrethroid.
- An operational plan has been developed should a BMSB population be found.
BMSB Council/Biosecurity management
- Probably only one generation per year is likely, may be two in Northland and Tauranga.
- There is a lot of research work in progress or completed that is now being co-ordinated.
- Import permissions have been gained from EPA and MPI for the Samurai parasitic wasp. Note that only MPI can use this tool.
- A highly-dosed insecticide impregnated ghost net can be used as a lure and kill trap or as an exclusion wall/net.
BMSB Chile experience
- Has entered the country with non-organic items.
- They are still attempting to control the population.
- New Zealand and Chile are working together.
- An app is being developed for smartphones to enable reporting of potential sightings.
- Monitoring is possible via pheromone traps and beating traps.
- BMSB produces an aggregation pheromone which could be used, but it is not effective as a ‘lure and kill’ trap. More work is being done.
- More likely cheaper to attempt eradication than pay for long-term management of BMSB.
- As BSBM migrates into orchards, boundaries can be treated with insecticide. Area wide treatments would be preferable.
- Insect proof netting is possible with 80-90% effectiveness.
- Is there a natural or importable parasitoid?
- Considering sterile insect technique (SIT).
- Kamikaze wasp importation being readied if an incursion were to occur.
Spotted wing drosophila
- All production in infected counties is now in cages.
- The impact of this pest on susceptible crops is worse than that for BSBM.
- Spinosad (eg Success) is the only known chemical option. This is registered for summerfruit.
- Eggs are laid in ripe fruit, with up to 13 overlapping generations per year. Population can double every four days.
- Broad host range, different fruit have varying acceptability to SWD. Peach fluff is a barrier. Raspberry seems very desirable.
- Damaged fruit is more accessible to SWD.
- Cherry is susceptible once it starts to colour.
- Care should be taken when changing to a harsher chemical control environment, as that may well be applications every 5-10 days with older style broad spectrum chemistry.
- Monitor and destroy boundary hosts.
- Lure and kill traps are being developed. Current traps can be less attractive than the crop!
- SWD numbers explode once it is established.
- In Chile there is trapping, looking at SIT and biological control.
After the meeting, Richard Mill and Juan Rosales from Summerfruit NZ were invited to participate in a workshop to learn about industry views on the matter and the work industry bodies are doing in preparation for a possible incursion of any of these pests.
More information can be found on the Summerfruit NZ website under Biosecurity.
Download our fact sheet on BMSB here.
Download our fact sheet on SWD here.
Samurai wasp EPA application
The Brown Marmorated Stink Bug (BMSB) is one the biggest biosecurity threats facing New Zealand and is frequently intercepted at our borders. It has the potential to cause significant economic damage to the horticulture industry and to home owners due to its invasive nature.
The BMSB Council made an application to the Environmental Protection Authority (EPA) to release the Samurai wasp to help combat a BMSB incursion should one be found in New Zealand.
Following approval from the EPA, the Samurai wasp (Trissolcus japonicus) can now be used to fight BMSB in the event of an incursion.
The BMSB represents one of the highest risk biosecurity threats to New Zealand. Several industry groups, including Summerfruit NZ, made an application to introduce the Samurai wasp as a biocontrol agent for this pest and a decision on this request was reached late August 2018. According to the EPA’s decision, the Samurai wasp may only be released in New Zealand after a stink bug invasion has been detected, and only at the location of the incursion. This is an extremely important achievement for horticultural industries and will be a very important tool in preparation for the effective and sustainable management of a potential BMSB incursion.
Download the Samurai wasp Q&A here.
Read When twenty-six thousand stink bugs invade your home by Kathryn Schulz, published 12 March 2018, The New Yorker.
Download our fact sheet on BMSB here.
Read MPI's factsheet on BMSB.