The world produces approximately 18 million tonnes of olives every year, and the olive fly (Bactrocera oleae) is the single biggest problem facing the majority of olive plantations around the world.
The Olive Fly Problem
Europe, particularly in Spain, Greece and Italy, accounts for 80% of the world’s production of olives and olive oil. In many olive-growing areas in the Mediterranean, the sole agricultural income comes from the olive crop. The olive fly has a serious impact on the local economy. Olive fly infestation, even at low levels, makes table olives unmarketable and adversely affects the acidity, and hence quality and value of olive oil.
Current control methods against olive fly rely overwhelmingly on the use of chemical insecticides. Olive fly females inject their eggs directly into the fruit, making it very difficult to kill the larvae – they are never exposed outside the fruit, so fruit-penetrating toxins must be used. Several useful insecticides have been, or are being, phased out due to concerns about their negative impact on the environment or human health. Insecticide-resistance is reducing the effectiveness of the chemicals used. The cost of chemicals is also high. For example, in Greece approximately €35 million is spent annually on control of olive fly to prevent estimated losses to the industry of €650 million. Some alternative control methods such as pheromone disruption, various lures and traps and the fruit fly parasite, Psyttalia concolor, have also been used to control olive fly but these methods have generally had little success, especially when population density is high.
Oxitec Olive fly solution (OX3097D)
OX3097D is a female-specific Oxitec strain. It can be used for population suppression without the need to irradiate insects. It also provides accurate separation of the sexes, allowing a 100% male release. Our Olive Fly strains have now undergone contained trials with excellent results and they are now ready for field trials.
In late July Oxitec Ltd, met with officials from the Ministry of Agriculture, Livestock, Fisheries and Food of the Government of the autonomous region of Catalonia in Spain, to discuss the recent submission of an application to conduct an outdoor netted cage study of the OX3097D strain of Olive fly. The OX3097D strain has been in development for several years and has demonstrated excellent results in contained greenhouse trials and is a promising candidate as a population suppression product for wild olive fly infestations. Additionally, evaluations conducted for environmental safety and human and animal health impacts have not revealed any areas of concern to Oxitec in this regard and all data has been submitted for evaluation under this application.
The costs associated with conducting research trials under containment as deemed appropriate by regulatory authorities are significant, and the timing for conducting investigations is critical as the collection of wild Olive flies for experimental purposes must take place during a narrow window of time in the autumn. At this stage in the evaluation of the Olive fly strain OX3097D, Oxitec has reviewed its portfolio of product candidates for Olive fly pest suppression programmes, and has determined that refocusing on new promising candidate strains will ultimately provide olive producers with the best solution Oxitec can offer. Oxitec has thus decided to withdraw its current application with the Government of Catalonia for a netted trial of OX3097D Olive fly, and intends to submit an application in the future with these new product candidates as we work towards developing solutions to control this devastating pest.
Why are scientists studying the olive fly? Olive fly is a destructive pest of olive trees, especially in the Mediterranean region. Olive fly costs farmers billions of dollars every year and makes olive oil from affected trees acidic and unusable. Olive fly has already developed resistance to newly introduced chemicals that are currently the main line of defence against this insect pest worldwide. A number of insecticides that have been traditionally used for control have also been phased out by new EU regulations. This means that better tools for controlling olive fly are urgently needed to save olive crops and help the people who depend on them.
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A finals de juliol, Oxitec Ltd es va reunir amb funcionaris de la Conselleria d’Agricultura, Ramaderia, Pesca i Alimentació del Govern de la Generalitat de Catalunya, per parlar de la recent presentació d’una sol·licitud per dur a terme un assaig de la soca de mosca de l’Olivera OX3097D a l’aire lliure, en una zona tancada amb malles. La soca OX3097D s’ha desenvolupat durant diversos anys demostrant excel·lents resultats en assajos d’hivernacle tancat, i és un candidat prometedor per suprimir les poblacions de la mosca de l’olivera. A més, les avaluacions realitzades sobre l’impacte en el medi ambient i la salut humana i animal no han indicat àrees de preocupació per Oxitec i totes les dades s’han presentat per a la seva avaluació en el marc d’aquesta sol·licitud.
Els costos associats a la realització d’assajos d’investigació sota confinament, segons van considerar apropiat les autoritats reguladores, són significatius, i el moment de realitzar les investigacions és fonamental atès que la recol·lecció de mosques de l’Olivera salvatges amb fins experimentals s’han de dur a terme durant una estreta finestra de temps a la tardor. En aquesta etapa de l’avaluació de la soca OX3097D, Oxitec ha revisat la seva cartera de productes candidats per a programes de supressió de la mosca de l’Olivera, i ha determinat tornar a centrar-se en noves soques candidates prometedores, que, en última instància, proporcionaran als productors d’oli la millor solució que Oxitec pot oferir. Per tant, Oxitec ha decidit retirar la seva sol·licitud actual amb el Govern de Catalunya d’un assaig confinat amb malla de la mosca de l’Olivera OX3097D, i té la intenció de presentar en el futur una sol·licitud amb aquests nous candidats a mesura que treballem cap al desenvolupament de solucions per al control d’aquesta devastadora plaga.
Per què els científics estudien la mosca de l’olivera? La mosca de l’olivera és una plaga destructiva d’oliveres, sobretot a la regió mediterrània. La mosca de l’olivera els costa milers de milions d’euros? als agricultors cada any i fa que l’oli d’oliva dels arbres afectats sigui àcid i inutilitzable. La mosca de l’olivera ja ha desenvolupat resistència als productes químics de recent introducció que són actualment la principal línia de defensa contra aquesta plaga d’insectes a tot el món. Un nombre d’insecticides que s’han utilitzat tradicionalment per al control també s’han eliminat per les noves regulacions de la UE. Això significa que es necessiten urgentment millors eines per al control de la mosca de l’olivera per salvar els cultius d’oliveres i ajudar a les persones que depenen d’ells.
A finales de julio Oxitec Ltd, se reunió con funcionarios de la Conselleria de Agricultura, Ganadería, Pesca y Alimentación del Gobierno de la Comunidad Autónoma de Cataluña en España, para hablar de la reciente presentación de una solicitud para llevar a cabo un ensayo de la cepa de mosca del Olivo OX3097D al aire libre, en una zona cerrada con mallas. La cepa OX3097D se ha desarrollado durante varios años, demostrando excelentes resultados en ensayos de invernadero cerrado, y es un candidato prometedor para suprimir las poblaciónes de la mosca del olivo. Además, las evaluaciones realizadas sobre el impacto enel medio ambiente y la salud humana y animal, no han indicado áreas de preocupación para Oxitec y todos los datos se han presentado para su evaluación en el marco de esta solicitud.
Los costes asociados a la realización de ensayos de investigación bajo confinamiento según consideraron apropiado las autoridades reguladoras son significativos, y el momento de realizar las investigaciones es fundamental dado que la recolección de moscas del Olivo salvajes con fines experimentales deben llevarse a cabo durante una estrecha ventana de tiempo en otoño. En esta etapa de la evaluación de la cepa OX3097D, Oxitec ha revisado su cartera de productos candidatos para programas de supresión de de la mosca del Olivo, y ha determinado volver a centrarse en nuevas cepas candidatas prometedoras, que, en última instancia, proporcionarán a los productores de aceite la mejor solución que Oxitec puede ofrecer. Por tanto, Oxitec ha decidido retirar su solicitud actual con el Gobierno de Cataluña de un ensayo confinado con malla de la mosca del Olivo OX3097D, y tiene la intención de presentar en el futuro una solicitud con estos nuevos candidatos a medida que trabajamos hacia el desarrollo de soluciones para el control de esta devastadora plaga.
¿Por qué los científicos estudian la mosca del olivo? La mosca del olivo es una plaga destructiva de olivos, sobre todo en la región mediterránea. La mosca del olivo les cuesta miles de millones de dólares a los agricultores cada año y hace que el aceite de oliva de los árboles afectados sea ácido e inutilizable. La mosca del olivo ya ha desarrollado resistencia a los productos químicos de reciente introducción que son actualmente la principal línea de defensa contra esta plaga de insectos en todo el mundo. Un número de insecticidas que se han utilizado tradicionalmente para el control también se han eliminado por las nuevas regulaciones de la UE. Esto significa que se necesitan urgentemente mejores herramientas para el control de la mosca del olivo para salvar los cultivos de olivos y ayudar a las personas que dependen de ellos.
Q: What is the next step for research?
A: Scientists will evaluate the performance of the Oxitec genetically engineered (GE) olive flies in netted field cages to assess their mating and lifespan.
Q: Who is Oxitec?
A: Oxitec is a UK-based company that was founded in 2002 as a spinout from Oxford University (the name comes from Oxford Insect Technologies). Oxitec is comprised of an international team of scientists pioneering a better way to control insect pests that damage crops and spread disease. Studies and field trials in different countries have shown that the approach is safe, effective and environmentally friendly.
Q: Who are the regulators for the proposed field cage trial?
A: Comissió Catalana de Bioseguretat (CCBS), Generalitat de Cataluña, with assistance from the Federal National Biosecurity Commission (NBC), Spain under Ley 9/2003 (the implementation of Regulation 2001/18/EC in Spain).
Q: Has the Oxitec olive fly been tested prior to the proposed netted study?
A: Yes, rigorously in laboratory and cage studies over several years and over more than 75 olive fly generations. In previous studies using field cages, the Oxitec olive fly was shown to effectively compete with wild males for mating with pest females, and worked well to control a pest olive fly population (eg, Ant et al. 2011; Ant et al. 2012). The next step is a larger cage study under outdoor conditions using olive trees inside netted enclosures. This will provide further information on the mating competitiveness and lifespan of Oxitec male olive flies in comparison to the pest olive flies from Spain under local conditions in a netted area.
Q: Why are scientists studying the olive fly?
A: Olive fly is a destructive pest of olive trees, especially in the Mediterranean region. Olive fly costs farmers billions of dollars every year and makes olive oil from affected trees acidic and unusable. Olive fly has already developed resistance to newly introduced chemicals that are currently the main line of defence against this insect pest worldwide. A number of insecticides that have been traditionally used for control have also been phased out by new EU regulations. Other forms of control including mass-trapping and use of parasitoids have not been successful in controlling this pest. This means that better tools for controlling olive fly are urgently needed to save olive crops and help the people who depend on them.
Q: How does olive fly damage olive crops?
A: Female olive flies are the problem because they lay their eggs in ripening fruit and newly hatched larvae feed on the fruit. These larvae either pupate in the olive or exit to pupate on the ground. A single female olive fly can cause significant damage because she lays one egg per fruit and can lay up to 800 eggs in her lifetime, affecting many olive trees. This is why new tools are needed to control female olive fly pests to reduce their numbers as low as possible in olive groves.
The female ‘oviposition stings’ on the fruit surface cause sufficient damage to prevent their use and lower the quality and value of pressed oil due to increased acidity from opportunistic infestations of fungi and bacteria. In areas of the world where the olive fly is established, it has been responsible for losses of up to 80% of oil value, and even 100% value loss for some table olive cultivars.
Q: Where did olive fly come from?
A: Olive fruit fly attacks on olive crops date back to biblical times and this fly has long been a major pest in the Mediterranean basin. The larvae only eat olive fruit in cultivated and wild olive trees so they are found where olive trees are grown. The olive fly has spread throughout the Mediterranean basin, South and Central Africa, Canary Islands, the Near and Middle East, California, and Central America. Despite its abundance and notoriety on cultivated olives in the Mediterranean region, the olive fruit fly most likely originated in regions of sub-Saharan Africa where wild olive varieties are found and from which domesticated cultivars were derived.
Q: How long do the olive flies live?
A: The life-cycle of olive flies (egg-to-reproducing adult) is circa 25-30 days in Mediterranean climates, but the life cycle is affected directly by temperature. Longevity will be one of the parameters we aim to measure in the proposed study.
Q: Where in Europe are olive trees grown?
A: Europe accounts for approximately 80% of olive oil production. Olive tree cultivation is widespread in Southern Europe with Spain, Italy and Greece as the main olive-producing countries, followed by Portugal, Croatia and Montenegro.
Q: How does Oxitec’s technology work?
A: Oxitec has developed genetically engineered strains of pest insects as a method of pesticide-free and species-specific control. The approach is similar to the sterile insect technique (SIT), which involves release of radiation-sterilized insects to mate with their wild counterparts, thereby reducing the pest population with successive releases. The SIT approach has been successfully used worldwide for more than 50 years to control insect pests such as New World Screwworm fly. However for olive fly, SIT approaches have so far been unsuccessful due to the damaging effects of the radiation and the absence of a male-only strain (releasing males is considered key to SIT-control of olive fly because released males and females mainly mate each other instead of the local pest population).
The Oxitec olive fly is inspired by the SIT approach, but doesn’t rely on radiation, which can affect many genes and the insect’s competitiveness. Instead, Oxitec uses one ‘self-limiting’ gene to induce ‘sterility’ and a colour marker gene for monitoring the results. Male flies are then released to mate with pest females. With successive releases there are fewer female offspring each generation and the pest population crashes.
Q: How can you distinguish between helpful Oxitec male olive flies and the pest ones?
A: Oxitec olive flies all carry a colour marker to track and trace them in the environment. They carry a gene that produces a fluorescent protein so that when it is viewed under a special light, it appears red. The marker is identifiable at all developmental stages of the insect. The pest olive fly females can’t tell the difference but we can identify them.
Q: Would organic farmers near the study site lose their organic certification?
A: No, this is a netted field cage trial. It’s worth noting that we are far from a hypothetical situation of genetically engineered olive fly being used as a commercially available tool in fields to control this invasive and destructive agricultural pest. This would be a scientific investigation of a research strain in an enclosure under controlled conditions in accordance with the regulatory permit.
An important distinction here is that the issue of GM crop ‘contamination’ of organic crops is due to the possibility that a modified plant trait could be adopted by the organic plant population. This is not the case with GM insects as the genes do not spread to the crops or other organisms. The genetic control of the pest insect is species-specific and self-limiting, and the insects and their genes do not persist in the environment.
The fact is that some research strains go ahead and others do not. Our purpose is to find environmentally friendly and effective pest control options for farmers. For that to happen the science must take place to honestly evaluate these tools.
Q: How would this affect the olive oil and olives that I buy as a consumer?
A: Not at all during this study because it is a scientific investigation, not a commercial project. The olives used for this study will not enter the market in any form and will be destroyed at the end of the trial. The aim is to evaluate the Oxitec olive fly as an effective and environmentally friendly form of pest control to provide farmers with improved ways to protect their olive crops. Better control of olive fly in future would result in higher crop yields and reduced acidity levels in the olives, for higher quality olive oil.
Q: What would happen if a person or animal accidentally ate an Oxitec olive fly?
A: They would get the same nutritional elements such as protein, fat, carbohydrate and others as they would from eating a wild olive fly, but they cannot take up genes through this route. The proteins from the self-limiting gene and colour marker are non-toxic and non-allergenic. The Oxitec olive flies are a biological, non-toxic method of pest control. If there were concerns about human or environmental safety, the regulatory authorities would not let a trial go ahead. This is a netted cage trial.
Q: Could Oxitec olive fly affect other species?
A: No, this is a netted study under controlled conditions. In fact an environmental benefit of this approach is that it’s a species-specific form of control. While pesticides or even other biological control methods like mass-trapping for instance can affect many species, the olive fly only mates successfully with its own species, therefore the genes and their effects are restricted to this single species of fruit fly. It is important to also note that in the presence of olive trees, olive flies only travel approximately 50m in their lifetime, so for future suppression trials, the control effect would be local and only affect the area in which they are released. Olive flies do not perform a key ecological role in pollination of crops.
Q: What about endangered species?
A: There would be no effect on endangered species because this is a netted study. Also olive fly is not an important food source for other species. There are 115 mammal species in Spain, of which 2 are critically endangered, 5 are endangered, 13 are vulnerable, and 3 are near-threatened. Most species include small mammals like elephant shrews and rodents, large mammals like wild cats, seals, dolphins and goats, none of which feeds on insects such as olive flies, or have significant habitat overlap.
Q: Would releasing Oxitec olive flies eradicate the olive fly from Europe?
A: No, this is a limited netted study. Even for larger suppression trials, the aim would not be eradication of the species, and that would not be practical – the aim is to give farmers a better tool for effective local pest control in areas where olive crops are grown.
Q: Would releasing Oxitec’s olive fly lead to increased number of other pests that normally compete with olive fly?
A: No, Olive flies are highly specialised to the olive crop and do not affect or compete against any other insect or fly for olives. Effects of controlling olive fly would be the same whatever method is used. Olive fly is already the subject of control measures with insecticides and trapping, and although there is increasing insecticide-resistance, increases in other pests have not been observed.
Q: Why aren’t these experiments being conducted in the UK where Oxitec is based?
A: There are no olive groves in the UK.
Q: What would happen to the olive flies at the end of the study?
A: Upon completion of the trial, the plots will be sprayed with insecticides and all fruit in the netted plots will be collected and destroyed. This will be followed by a monitoring phase to ensure that the study olive flies have been removed.