The world’s first field trial of a genetically-modified olive fly could start in Catalonia next year if a British biotech firm wins approval from relevant authorities.
Generally, we would look to outnumber the wild males by about 10 to 1
Oxitec proposes to do the trial in collaboration with — and on land belonging to — the Catalan agriculture, food and aquaculture research institute IRTA.
Here, Oxitec CEO Hadyn Parry answers our questions about the plan, which would also be the first field test of a GM insect in the European Union.
What stage are you at in the application process?
Hadyn Parry: It’s being considered by the Catalan government and at the Federal level by the Spanish National Biosafety Commission. The next step is the publication of the call for public comment of which there are two processes: one at the European Commission Joint Research Centre level, which is for information, and the other for comments to be submitted to the Catalan government.
The first of these has already taken place and we are anticipating the second one shortly. At that stage anyone can comment on the application. The Catalan authorities then need to assimilate the comments and determine if they need additional information from us or make a decision. We anticipate a decision in the (northern) spring.
Would it be the world’s first such trial of a GM olive fly?
Yes, it would. But of course we have trialed our GM mosquitoes with great effect in Cayman and Brazil.
Aside from potentially improving olive production, what impact could heavily reducing or eliminating wild olive fly populations have?
The impact of a reduction in the olive fly population is the same no matter what method you use to achieve it. If one was to release the Oxitec flies and then stop, the wild olive fly population would recover. In the same way, if you hit the population hard with pesticides and then stop, it comes back.
The key is species specificity compared to other approaches. Longer term, we believe use of the Oxitec olive fly for a pest control solution will result in a smaller environmental impact than conventional mass trapping or pesticide applications which are not species-specific.
What do olive flies feed on and what feeds on them?
Adult olive flies feed on nectar, decaying fruit and, when available, bird feces. The larvae develop in olives.
Opportunistic ‘generalists’ such as bird and reptile species might feed on adult life stages and ants on the pupae. But there are no ‘keystone’ species, that is ones that are predominantly dependant on the olive fly.
What’s your response to scientific group Testbiotech’s fear the GM flies could escape and their larvae offspring end up in olives in commercial plantations?
Bear in mind this is a relatively isolated site and the trial is netted. Typically they fly 50 – 300m and if mates and food are present they stay very local.
Notwithstanding this, the Oxitec male olive flies are subjected to such a strong negative selective pressure from the inherited lethality trait that they are not capable of spreading and establishing in the environment. The whole control concept is based on not breeding effectively and not remaining in the environment.
What about the concern that it is not known how your insects will interact with changing environmental conditions?
This is why one does step-by-step, careful trials. It’s critical that these are done within the regulatory process and we often use respected third parties to make sure the trial design and running of the trial are done in the most professional way.
The process for testing pharmaceuticals involves pre-clinical tests to gather as much information as possible then phased testing. Similarly, we do extensive laboratory and field cage testing and evaluate the strain as far as possible without an open release. Data from these trials show the strain performs well. Then at some point one must go into the field. Hence here we are doing this in a netted trial – and it is the purpose of this trial to determine how the Oxitec olive flies interact with changing environmental conditions.
Will you release your environmental risk assessment for the proposed trial?
The regulatory authorities are still reviewing the file but once they are ready the risk assessment can be requested by any party directly from them.
The environmental risk assessment is a key part of the process and was carried out following the (2012) EFSA (European Food Safety Authority) draft guidance document for conducting an environmental risk assessment of genetically modified animals.
Once a wild olive fly population was heavily reduced or eliminated, how would this be maintained?
In the proposal, weekly or twice weekly releases are discussed. The numbers depend on many factors but generally we would look to outnumber the wild males by about 10 to 1. So if there were say 100 wild males (which could well be the case) in each plot then we’d look to release 1,000 in each plot.
Longer term, there are options — one can consider an area wide use – where you aim to control the olive fly and keep it at a low level throughout the year in an area with repeated releases.
Another option is to use this approach in autumn as the olive fruit is about to form and potentially again in spring – in other words to reduce the pest threat at the time of year when numbers and damage would otherwise escalate.
Alternatively, it could be combined with other interventions as part of an overall integrated pest management plan.
The annual cycle of the olive fly is such that there is a big adult population peak as the fruit forms in autumn and a small adult population peak in the spring which is reliant on the olives which remain on the trees after the previous harvest.
The most obvious control scenario in my view is a pattern of releases in the pre-peak part of the year (August, September, October – but the timing depends on temperature to an extent) that prevents that adult population peak occurring. Reducing that peak also will have knock on consequences of reducing the over-wintering population and hence contribute to the following year’s control.
In almost all crop protection situations there is a damage threshold – you rarely try and eliminate. What you do is assess the planned marketability of the crop, the cost of potential damage and the cost of intervention, and then make a decision as to the crop protection strategy.
Why did you choose Tarragona and not, say, Andalusia, where most of Spain’s olive oil sector is located?
We did talk to stakeholders in Andalusia and they were very positive. But when looking around sites we wanted a relatively small, isolated site so we didn’t have a nearby farmer spraying insecticides. The potential sites we looked at in Andalusia were all very large sites. Catalonia made more sense from a practical trial perspective.
The trial would basically involve six plots on one site, each plot being about 0.14ha (e.g. 12m x12m) and having four trees.
Would any payment or other recompense for this trial be made to any person or organization in Spain or the European Union?
We expect to cover local contractor or actual trial running costs (labor costs, consumables, etc.) but we are not expecting any additional costs or fees.
Are similar trials planned elsewhere?
Farmers in other countries such as Greece and Italy have contacted us as they are very interested in this method of control of olive fly. Hence we included in the application that we may seek approval for further countries in due course.
Do you have any costings to show how using the GM olive fly compares to using pesticides to control wild olive flies?
No sorry, we don’t. It is really early days at the moment. But the International Atomic Energy Authority has long had olive fly as one its key targets for radiation based sterile insect control and they, in the past, have published their economic feasibility studies.
Clearly we think our approach will have significant benefits over current interventions and be cost effective. We see advantages, too, over a radiation based approach, should that be feasible. Our olive flies are also marked, making monitoring simple and effective.