Science in Society Archive

Regulation of Transgenic Insects Highly Inadequate and Unsafe

USDA set a dangerous precedent for a permissive regulatory regime over environmental releases of transgenic insects that is now adopted across the world Dr. Mae-Wan Ho

USDA’s Environmental Impact Statement “scientifically deficient”

Belatedly, the scientific community has woken up to the parlous state of regulation over the environmental release of genetically modified or transgenic insects. Scientists at the Max Planck Institute for Evolutionary Biology in Plön, Germany assessed the regulatory process in detail and find it distinctly unsatisfactory in a commentary published January 2012 [1]. It is more than ten years since ISIS objected to the environmental release of transgenic pink bollworm moths ([2] Terminator insects give wings to genome invaders, ISIS report) proposed by the US Department of Agriculture (USDA).

Over the past 9 years, 14 US government-funded field trials have taken place of the GM pink bollworm moth, an agricultural pest of the cotton plant; but there has been no scientific publication of experimental data in all that time, and in only two instances have permit applications been published [1]. When the German scientists requested information from the USDA on the unpublished applications, they were refused; and had to submit a Freedom of Information Act request. Even then, no experimental data were forthcoming, most likely because the data did not exist; as an administrative procedure allows US regulators to rely on earlier similar environmental assessments; and that procedure is applied all too often.

Not surprisingly, the world’s first environmental impact statement (EIS) on transgenic insects issued by US Department of Agriculture in 2008,was judged [1] “scientifically deficient” in considering environmental risks, relying largely on unpublished data and basing endorsement for releases on just two laboratory studies on the Mediterranean fruit fly Ceratits capitata, which is just one of the four species covered by the document. The other species were the pink bollworm moth P. gossyfiella, the Mexican fruit fly Anastrepha ludens, and the oriental fruit fly Badrocera dorsalis. In fact, the same EIS also claimed “some applicability” for transgenic mosquitoes Aedes or Anopheles.

The EIS made selective use of unpublished or non-peer reviewed ‘evidence’ to support contentious conclusions, a practice explicitly forbidden by US federal regulations in drafting EIS.

Another problem with the EIS is that it dealt only with first generation transgenic insect technology that involves either the expression of fluorescent markers for monitoring population size, or the use of repressible dominant lethals (RDLs) to kill all offspring of individuals released into the environment, or all the female insects in release programmes requiring only male insects, with the intention to reduce wild populations [3, 4] (Terminator insects – a primer, Terminator Insects – The Killing of Females, ISIS reports). Newer techniques for replacing rather than reducing natural populations were not considered.  Furthermore, the document appears to treat all genetic modifications as equivalent, which is definitely not the case, as some modifications are more effective, or less risky than others.

Nevertheless, this highly inadequate EIS from the USDA APHIS (Animal and Plant Health Inspection Service) set the tone for the permissive regulation of transgenic insect releases all over the world.

Worldwide releases of transgenic insects follow USDA model

Within the past several years, there have been several environmental releases of transgenic insects that follow the USDA model.

Oxitec, a UK company based in Oxford, is in the frontline of developing transgenic mosquitoes for controlling infectious diseases such as dengue.  Their intention to carry out an international series of field releases of transgenic mosquitoes first came to light in Malaysia in 2008 ([5] Terminator Mosquitoes to Control Dengue? SiS 39). Although that particular release was halted, the company has since resorted to illegal, secret field releases across the world, aided and abetted by regulatory authorities.

According to a briefing from Friends of the Earth in the United States [6], the first field release of transgenic mosquitoes from Oxitec took place between 2009 and 2010 in the Cayman Islands, a British Overseas Territory, and consisted of 3 million mosquitoes. Malaysia was the second to host Oxitec’s experiments at the end of 2010 with 6 000 more transgenic mosquitoes released. Then, between February and June 2011, more than 33 000 were released in Brazil. The first releases on Cayman Islands took place in secret with no public consultation, and no informed consent. There are no biosafety laws on Cayman Islands, despite the fact that the UK is a Party to the Cartagena Protocol on Biosafety. Similarly, the release in Malaysia in 2010 was only made public in a press release dated 25 January 2011, more than a month after the trial began on 21 December 2010.

While the Cayman Islands regulatory authorities failed to publish any regulatory documents prior to the release of transgenic mosquitoes, the Malaysian regulatory authorities failed to cite published experiments in their regulatory documents [1].

A document [7] entitled: “Risk Analysis – OX513A Aedes aegypti Mosquito for Potential Release on the Cayman Islands (Grand Cayman)” was uploaded to the UK parliament website on 13 January 2011, more than a year after the release commenced, and only as the result of questions asked at the House of Lords. It made reference to unpublished reports and other dubious sources to support key assertions [1], such as “The characteristics of the OX413A Aedes aegypti have been thoroughly evaluated by several institutions worldwide, e.g. in France, Malaysia..and Thailand.”, and “OX513A uses genetic methods instead of radiation to achieve sterility, therefore the genetically sterile insects have been reported to be fitter and competitive…”

Oxitec has planned to release more transgenic mosquitoes in the Florida Keys early in 2012, though this has been delayed [6], perhaps partly as the result of public outcry.

Other countries reported to be evaluating the release of transgenic insects include France, Guatemala, India, Mexico, Panama, Philippines, Singapore, Thailand, and Vietnam [1].

Hazards for health and environment ignored

The most troubling aspect of Oxitec’s document, according to the German scientists, is [1] “the absence of any discussion of potential environmental or health hazards that are specific to the released OX513A stock.”

The particular RDL construct in OX513A is engineered to express the synthetic protein tTA at very high levels, and female mosquitoes biting humans could inject it into their bloodstream with potential harmful consequences. Females expressing high levels of tTA can arise if a resistance to the RDL construct evolves in the wild, or if female transgenic mosquitoes were not completely excluded by the sorting mechanism. More significantly, OX513A males are known to be only partially sterile, and when they mate with wild females, they will produce 2.8 to 4.2 % the normal number of eggs, half of which will be biting daughters.

Another major hazard is the potential for horizontal gene transfer through the remobilization of the transposon-derived vectors used in creating the first generation transgenic insects, which we have highlighted in ISIS’ original submission to the USDA [2], and reiterated several times since, most recently in [8] Can GM Mosquitoes Eradicate Dengue Fever (SiS 50). We provided evidence that the disabled piggyBac vector carrying the transgene, even when stripped down to the bare minimum of the border repeats, was nevertheless able to replicate and spread, because the transposase enzyme enabling the piggyBac inserts to move can be provided by transposons present in all genomes, including that of the mosquito. The main reason initially for using transposons as vectors in insect control was precisely because they can spread the transgenes rapidly by ‘non-Mendelian' mean within a population, i.e., by replicating copies and jumping into genomes, thereby ‘driving’ the trait through the insect population. However, the scientist neglected the fact that the transposons could also jump into the genomes of the mammalian hosts including human beings. Although each transposon has its own specific transposase enzyme that recognizes its terminal repeats, the same enzyme can also interact with the terminal repeats of other transposons, and evidence suggests extensive cross-talk among related but distinct transposon families within a single eukaryotic genome.

The use of the piggyBac transposon has been plagued by problems of instability in transformed Aedes aegypti [9]; and large unstable tandem inserts of the piggyBac transposon were prevalent [ 10]. In spite of instability and resulting genotoxicity, the piggyBac transposon has been used extensively also in human gene therapy [11]. A number of human cell lines have been transformed, even primary human T cells, using piggyBac [12]. These findings leave us in no doubt that the transposon-borne transgenes in the transgenic mosquito can transfer horizontally to human cells.  The piggyBac transposon was found to induce genome wide insertion mutations disrupting gene functions.  Female A. aegypti mosquitoes mate as a rule before taking a first blood meal [13].  Thus living human blood will be exposed to the piggyBac carried by the mated female.  What would it take to activate the mosquito-borne transposon to infect human blood? Joe Cummins pointed out [8]: “No more than an encounter with Baculovirus [acting as a stimulus] that could enter through open cuts or sores, or with inhaled dust.  The piggyBac transposon GM construct could wreak havoc in the human genome, causing numerous insertion mutations and other untold, unpredictable damage.”

There are yet other reasons why transgenic mosquitoes are not a solution to controlling disease vectors (see [14] Transgenic Mosquitoes Not a Solution, SiS 54).

Article first published 22/02/12


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  2. Ho MW. Terminator insects give wings to genome invaders. ISIS report, 19 March 2001,
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  4. Ho MW and Cummins J. terminator insects – the killing of females. ISIS report, 20 March 2001,
  5. Cummins J and Ho MW. Terminator mosquitoes to control dengue? Science in Society 39,33-35, 2008.
  6. Genetically engineered mosquitoes in the U.S. Issue Brief, Friends of the Earth, Washington DC,
  7. Countess of Mar. Question asked to Her Majesty’s Government 13 January 2011. Column WA450-WA451. Lords Hansard. Available:
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  12. Galvan DL, Nakazawa Y, Kaja A, Kettlun C, Cooper LJ, Rooney CM, Wilson MH. Genome-wide mapping of PiggyBac transposon integrations in primary human T cells. J Immunother 2009, 32(8), 837-44.
  13. Putnam JL, Scott TW. Blood-feeding behavior of dengue-2 virus-infected Aedes aegypti. Am J Trop Med Hyg 1995, 52(3), 225-7.
  14. Ho MW. Transgenic mosquitoes not a solution. Science in Society 54 (to appear) 2012.

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Katheryn Kerr Comment left 27th January 2016 18:06:13
Is this what has caused the Microcephly in babies from the recent Zika outbreak in Brazil?