Beetles for Methyl Bromide Research

Work at Plant & Food Research has led to ground breaking insect breeding systems to help find an alternative to methyl bromide for exporting forestry products.

Forestry products (including logs and milled timber) are New Zealand’s third largest export sector behind dairy and meat. The value to our economy of pine log exports annually is in excess of $2 billion dollars. Our key markets are China and India, along with Australia, South Korea, South East Asia and Japan. China and India in particular have strict bans on any insect “passengers” on those logs – especially bark beetles.

STIMBR (Stakeholders in Methyl Bromide Reduction) is the entity under which alternatives are being identified to replace methyl bromide. It is currently used as a phytosanitary treatment, mainly for logs that are exported. The treatment is required to meet importing countries’ phytosanitary requirements.

Methyl bromide is a highly effective phytosanitary treatment but it is expensive and carries some environmental risks – primarily as an ozone depleting substance (recognised by a United Nations Environment Programme, The Montreal Protocol).

There are now international requirements to stop the use of methyl bromide as a soil fumigant, and where it is used for phytosanitary and quarantine purposes, to manage methyl bromide emissions (through the use of “recapture and destruction” technologies).

New Zealand’s Environmental Protection Agency (EPA) introduced requirements for all methyl bromide recapture technologies to be used with all methyl bromide fumigations in this country beyond 2020. This was driven by the need to protect the environment (i.e. to reduce the damage to the ozone layer).

STIMBR represents a range of organisations and individuals who have a shared interest in finding alternatives for, and to manage, methyl bromide emissions.

STIMBR administers a range of research programmes. It has partnerships with MPI, the University of Canterbury, Plant & Food Research, and Scion. In 2011, MPI commenced investment through the PGP in a programme of work led by STIMBR. AGMARDT funding has supported some of this work.

In the past 7 years, several workstreams investigating potential alternatives have been explored including:

1. a) alternative chemical fumigants
2. b) physical treatments
3. c) an ecological approach – to determine if there are any times of the year when the problem insects are inactive or not present in logs, creating an “area freedom” in which to export.

One of the alternative chemical fumigants identified by the programme has been ethanedinitrile (EDN). In the 1960s it was used in the fertiliser manufacturing industry. In 1990 it was put forward by CSIRO (in Australia) as a potential alternative to methyl bromide.

EDN is absorbed rapidly into logs and wood, acting quickly and breaking down quickly to substances such as carbon dioxide and ammonia. It is delivered in the same way as methyl bromide but doesn’t need a heater to make the gas.

The other advantage of EDN is that, after a 24 hour fumigation, there is an extremely low level of residual gas remaining in the airspace under the tarpaulin, indicating there is no need for recapture technology (as is the case for methyl bromide in the future).

In February 2018 the EPA announced that is has received an application to import and use EDN in New Zealand. It is hoped the EPA will make a decision by early July 2018.

EDN is a toxic fumigant, like methyl bromide or phosphine, intended for use in the control of pests in stored grains, timber and logs. EDN is a product of a chemical oxidation reaction in which hydrogen cyanide is oxidized in a catalytic system in the presence of an organic solvent and water. The resulting compound, EDN, is stable as both a liquid and a gas (fumigant).

Initially it was thought that EDN wasn’t going to work on logs but it was tested by STIMBR and the results were promising enough to continue the research. But the programme needed large numbers of beetles to validate the initial findings. This is where Plant & Food Research came in…

The problem insects for pinus radiata are; the burnt pine longhorn, and two bark beetle species.

Plant & Food Research was contacted by STIMBR and asked to produce the large numbers of beetles required for the EDN research. Techniques have now been developed to establish self-sustaining colonies of wood boring insects. This has meant that verifiable research into methyl bromide alternatives can be carried out.

Graeme Clare is an entomologist at Plant and Food. Graeme and Group Leader of Applied Entomology, Libby Burgess, are leading a team at P&FR at Mount Albert in Auckland that has successfully developed protocols for maintaining laboratory colonies of the bark beetles Hylastes ater and Hylurgus ligniperda; to supply over thousands of individual insects to the disinfestation laboratory developing efficacy data for the phytosanitary fumigants methyl bromide and EDN.   

This ground breaking science allows high quality insects in the required numbers to be delivered, on planned dates, to the disinfestation team. 

Graeme’s innovative approaches to cracking something others had not achieved has contributed significantly to ensuring that robust data could be collated to support MPI in market access negotiations.

Despite the pressing need to breed the beetle in captivity for research, all previous attempts around the world had failed.  By any standards it was a massive challenge.

Graeme says little was known about the insect, even how many stages it went through in its life cycle. The biggest initial hurdle was to find and extract enough eggs from the insect’s tiny burrows in tree bark to meet the big production targets.

Bark ‘biscuits’ tied together with rubber bands were easy to handle but getting to the eggs was very hard. The team tried a range of methods. The first major breakthrough came when Graeme tried pre-slicing the bark – actually the soft moist phloem inner layer of the bark – and packaging the phloem between plastic cards. It then became a simple matter to disassemble the ‘bark sandwiches’ and extract eggs under a microscope.

Graeme and his team also discovered that the target species lay eggs after feeding – but the time frame between feeding and egg production differs between species. Golden haired bark beetle lay their eggs after two weeks of feeding – whereas the black pine bark beetle don’t lay eggs for another four weeks.

Sexing beetles was also extremely difficult in one species - males make a noise – females don’t. The team came up with the novel idea to use a stethoscope to listen for the male’s call.

The group then went on to design and test every aspect of insect management - diet, microbe and fungus control, storage, airflow, temperature, humidity and transport for two different species - before they could finally produce enough insects of a consistent quality for the demanding production schedule.

The world’s only bark beetle raising facility has now produced around 200,000 insects and collects more than 20,000 eggs a month.

Graeme says the whole project was a long slog but ultimately very rewarding.

He and his team were awarded the 2017 Forest Owners Award for Science of International Quality.

Graeme presented to the international Forestry Quarantine Working group in Rotorua last year.