Non-Native Strains of Genetically Modified Insects Risk Spread of Pesticide Resistance

Today environmental and civil society groups on five continents warned that plans to release non-native strains of genetically modified (GM) flies in olive fields in Spain and fruit orchards in Brazil pose major risks to crops and the environment, as pesticide resistance or other harmful traits could spread into wild pest populations.



Today environmental and civil society groups on five continents warned that plans to release non-native strains of genetically modified (GM) flies in olive fields in Spain and fruit orchards in Brazil pose major risks to crops and the environment, as pesticide resistance or other harmful traits could spread into wild pest populations.

The UK-based company Oxitec plans to release GM olive flies in Spain and GM Mediterranean Fruit Flies (Medfly) in Brazil in the coming months (3). Both applications, made in January 2013, are for experimental open releases of the GM flies and are currently being considered by regulators. Oxitec’s agricultural pests use a “female-killing” approach in which female offspring of the GM insects mainly die as larvae. Mass releases of multiple millions of GM male insects are intended to suppress the number of pests by mating with wild females. The olive fly strain used by Oxitec is not native to Spain but was created from a Greek strain back-crossed with Israeli strains; the Medfly strain to be used in Brazil appears to originate from Guatemala (4). Studies of olive flies in Greece have identified different levels of resistance to different pesticides in different locations (5).

Release of non-native strains of pests is normally prohibited under plant pest control regulations in the EU because undesirable traits such as pesticide resistance, which may be present in the newly-introduced strain, can spread into the wild population when the flies mate. In the UK, a proposed release of GM diamond back moths was halted because Oxitec planned to use a non-native strain (1). The UK regulators warned Oxitec about “uncertainty as to whether your non-indigenous strain may contain insecticide resistance genes that are not present in UK moths” and advised the company to start its experiments by modifying a native strain. Even an experimental release of a non-native strain of pest is risky because the spread of pesticide resistance or other traits into wild native flies cannot be prevented or reversed. Due to this and other concerns environmental groups have already called for the proposed trials to be halted (2). Other major concerns include the large numbers of dead and living GM larvae that will end up in the fruit, and the impact of GM insects on ecosystems.

Use of non-native strains is reckless because Oxitec’s GM pests are not sterile and the non-native strain of GM males will survive and breed with wild flies for many generations,” said Dr. Helen Wallace, Director of GeneWatch UK. “It is very risky to introduce non-native strains of pests into a new country. Harmful traits such as pesticide resistance would be impossible to eradicate once they spread through the wild population.”

“It is shocking to learn that Oxitec was blocked from releasing non-native GM agricultural pests in England, but now plans to try the same approach in Spain,” said Blanca Ruibal of Friends of the Earth Spain. “Instead of learning lessons from previous mistakes the company seems to want to push ahead regardless and put our olive groves at risk.”

“Oxitec’s proposed open releases of non-native GM flies in Spain and Brazil are clearly a bad idea, and is another instance of the company rushing into field testing of its GM insects without scientific review and public consultation,” said Silvia Ribeiro of the ETC Group.

In 2012 a planned release of Oxitec’s GM mosquitoes in the Florida Keys was delayed due to widespread public opposition and a campaign by Friends of the Earth-US and allies which called into question environmental and public health risks and lack of adequate regulations. The Florida Keys Mosquito Control District is once again considering what would be the first-ever U.S. release of genetically engineered mosquitoes into the wild, and has allocated funding in its budget for this activity in the coming year pending approval of the field trial by regulators.

From Brazil to Spain to the Florida Keys, Oxitec is once again playing Russian roulette and putting the pursuit profits ahead of common sense by introducing these GM insects into the environment which could potentially destabilize ecosystems and harm human health” said Dana Perls of Friends of the Earth-US. “Once these engineered organisms are released, they can’t be recalled and we must evaluate these very real risks through a serious and thorough environmental impacts review process before they are unleashed on the world. We are confident that any truly impartial, science-based reviews will lead to the cancellation of these risky experiments.”

For further information contact:

Silvia Ribeiro, ETC Group:  Tel: +52 55 5563 2664

Luca Colombo: FIRAB (Fondazione Italiana per la Ricerca in Agricoltura Biologica e Biodinamica) Tel.:   +39 06 45 43 74 85; Mob.:   +39 348 39 88 618

Eve Mitchell, Food & Water Europe:  Tel: + 44 (0)1381 610 740

Blanca Ruibal: Friends of the Earth Spain: 00-34-691471389 (mobile); 00-34-913069900 (office)

Dana Perls, Friends of the Earth US: Tel: 510-978-4425

Bob Phelps, Gene Ethics (Australia): Tel: 1300 133 868 or 03 9347 4500 {Int Code +613}

Dr Helen Wallace, GeneWatch UK:  +44-(0)1298-24300 (office); +44-(0)7903-311584 (mobile)

Frances Murrell, MADGE Australia Inc.: Mob 0401 407 944

Elizabeth Bravo, RALLT (La Red Por una América Latina Libre de Transgénicos): tel + 593 (2) 254 7516.

Lim Li Ching, Third World Network: +6012 2079744

Notes for Editors:

(1)   Feedback from the UK Scientific Advisory Committee on Genetic Modification (SACGM) to Oxitec (5th December 2011):  

(2)   Press releases: and[cid]=566989&als[itemid]=573179 ; Briefing:

(3)   Oxitec’s application to release GM olive flies in Spain: ; Oxitec’s Brazilian partner Moscamed’s application to release GM Medfly (Ceratitis capitata) in Brazil [in Portuguese]:

(4)   Ant T, Koukidou M, Rempoulakis P, et al. (2012) Control of the olive fruit fly using genetics-enhanced sterile insect technique. BMC Biology10:51.;  Morrison NI, Segura DF, Stainton KC, Fu G, Donnelly CA, Alphey LS (2009) Sexual competitiveness of a transgenic sexing strain of the Mediterranean fruit fly, Ceratitis capitataEntomologia Experimentalis et Applicata133(2):146–153.

(5)   Daane KM, Johnson MW (2010) Olive Fruit Fly: Managing an Ancient Pest in Modern Times. Annual Review of Entomology55(1):151–169

Friends of the Earth US News Release, “Controversial release of genetically engineered mosquitoes delayed” Jan. 4, 2012.