Genetically Modified Insects

Genetically modified insects

The release of sterile insects into “small populations” of target insects can reduce the target insect population.

However, the release of sterile insects into “dense target populations” does not effectively reduce the target insect population.

The sterile insect technique is a method of biological insect control, whereby overwhelming numbers of sterile insects are released into the wild.

The released insects are normally male, as the females cause the damage usually by laying eggs in the crop, or, in the case of mosquitoes, taking blood from humans.

The sterile males compete with wild males to mate with the females.

Females that mate with a sterile male produce no offspring, thus reducing the next generation’s population.

Repeated release of sterile males can diminish small populations, although success with dense target populations have not been demonstrated.

The technique has successfully been used to eradicate the Screw-worm fly (Cochliomyia hominivorax) in areas of North America.

Many successes controlled species of fruit flies, most particularly the Medfly (Ceratitis capitata) and the Mexican fruit fly (Anastrepha ludens).

Insects are mostly sterilized with radiation, which might weaken them if doses are not correctly applied, reducing their fitness.

The sterile insect technique has many other “drawbacks”.

Repeated treatment is sometimes required to suppress population before the use of sterile insects.

Sex separation can be difficult, though this can be easily performed on Medfly and screwworm.

Radiation treatment can reduce male mating fitness.

The technique is species specific.
For instance, the technique must be implemented separately for each of the 22 Tsetse fly species.

Mass rearing and irradiation require precision processes.
Failures have occurred when unexpectedly fertile breeding males were released.

Migration of wild insects from outside the control area could recreate the problem.

The cost of producing sufficient sterile insects can be prohibitive in some locations.

The drawbacks associated with the sterile insects technique [coupled with it’s failure to control “dense target populations”] appears to have encouraged Oxford Insect Technologies (Oxitec) to develop genetically modified insects.

Using recombinant DNA technology to create genetically modified insects called RIDL (“release of insects carrying a dominant lethal”) is under development by UK company Oxford Insect Technologies (Oxitec).

They introduce a repressible “dominant lethal” gene into the insects.

This gene kills the insects but can be inhibited by an external additive (tetracycline) that allows the insects to be cultivated in bulk.

This external additive can be administered orally via insect food.

The insects can be given marker genes, such as DsRED fluorescence, that enable monitoring of the eradication progress under field conditions.

Among several approaches to RIDL, the more advanced forms employ a female-specific dominant lethal gene.

This avoids the need for a separate sex separation step, as the inhibitor can be withdrawn from the final stage of rearing, leaving only males.

Males are then released into the target region.

The released males are not sterile, but female offspring express the dominant lethal gene, reducing survival rates to some 5%.

Since the males are not sterilized by radiation before release, they have equivalent fitness to wild males.

Progress towards applying this technique to mosquitoes has been made by researchers at Imperial College London, who created the world’s first transgenic malaria mosquito.

A similar technique is the daughterless carp, a genetically modified organism produced in Australia by CSIRO in the hope of eradicating introduced carp from the Murray River system.

As of 2005, it was undergoing safety tests.

The British company Oxitec use a technique called RIDL (Release of Insects with Dominant Lethality), that can produce fertile male adults that induce a high mortality of the descendants.

The adults generated with this technique and released in the environment are not sterile but their descendants have a survival rate of 0%
(this lethality can be switched off by introducing the antibotic, tetracycline, into their diet).

This company is currently(written 3/23/15) working on releasing these insects into Florida Keys, reducing the amount of wild insects that carry disease.

Unsurprisingly, there are “concerns” regarding genetically modified insects especially regarding the possible development of “antibiotic resistant genes”.

There are concerns about using tetracycline on a routine basis for controlling the expression of lethal genes.

There are plausible routes for resistance genes to develop in the bacteria within the guts of GM-insects fed on tetracycline and from there, to circulate widely in the environment.

For example, antibiotic resistant genes could be spread to E.coli bacteria and into fruit by GM-Mediterranean fruit flies (Ceratitis capitata).

GM olive flies and diamondback moths (Plutella xylostella) may also spread antibiotic resistance genes into the food chain via olives or brassica crops, affecting animals that eat them.

Other species, such as rodents, flying squirrels or earthworms could also play a role in disseminating antibiotic resistance, perhaps into diseases that they carry.

Antibiotic resistance genes in the guts of GM-mosquitoes may be transferred to animals directly if they are swallowed as adults, or passed on to mates and larvae and thus to water supplies.

Breeding GM-insects using tetracycline breaches existing policies.

These advise against mass feeding of antibiotics to animals worldwide and in some countries, the practice is banned, e.g. in the E.U. and Brazil.

These “concerns” are underlined by the survival rate observed [in the wild] to be “some 5%” i.e. not “0%” .

The adults generated with this technique and released in the environment are not sterile but their descendants have a survival rate of 0%
(this lethality can be switched off by introducing the antibotic, tetracycline, into their diet).

The released males are not sterile, but female offspring express the dominant lethal gene, reducing survival rates to some 5%.

The increasing burden of dengue, and the relative failure of traditional vector control programs highlight the need to develop new control methods.

SIT using self-limiting genetic technology is one such promising method.

A self-limiting strain of Aedes aegypti, OX513A, has already reached the stage of field evaluation.

Sustained releases of OX513A Ae. aegypti males led to 80% suppression of a target wild Ae. aegypti population in the Cayman Islands in 2010.

Here we describe sustained series of field releases of OX513A Ae. aegypti males in a suburb of Juazeiro, Bahia, Brazil.

This study spanned over a year and reduced the local Ae. aegypti population by 95% (95% CI: 92.2%-97.5%) based on adult trap data and 81% (95% CI: 74.9-85.2%) based on ovitrap indices compared to the adjacent no-release control area.

The mating competitiveness of the released males (0.031; 95% CI: 0.025-0.036) was similar to that estimated in the Cayman trials (0.059; 95% CI: 0.011 – 0.210), indicating that environmental and target-strain differences had little impact on the mating success of the OX513A males.

We conclude that sustained release of OX513A males may be an effective and widely useful method for suppression of the key dengue vector Ae. aegypti.

The observed level of suppression would likely be sufficient to prevent dengue epidemics in the locality tested and other areas with similar or lower transmission.

Suppression of a Field Population of Aedes aegypti in Brazil by Sustained Release of Transgenic Male Mosquitoes
Danilo O. Carvalho, Andrew R. McKemey, Luiza Garziera, Renaud Lacroix, Christl A. Donnelly, Luke Alphey, Aldo Malavasi, Margareth L. Capurro
PLOS Neglected Tropical Diseases – 2 July 2015

Releases of the genetically engineered Oxitec mosquito, commonly known as ‘Friendly Aedes aegypti’, reduced the dengue mosquito population in an area of Juazeiro, Brazil by 95%, well below the modelled threshold for epidemic disease transmission.

Oxford, UK, 2nd July 2015
Oxitec Ltd

Aedes aegypti in Dar es Salaam, Tanzania

The yellow fever mosquito (Aedes aegypti) is a mosquito that can spread Dengue Fever, Chikungunya, Zika Fever and Yellow Fever viruses, and other diseases.

These “concerns” are further underlined by the increase in congenital microcephaly in Brazil which emerged “a few months after the introduction of Zika virus (ZIKV) infection into the country” because the Zika virus can be spread by the yellow fever mosquito [Aedes aegypti].

North East Brazil

The Secretariat of Health Surveillance (SVS) of the Brazil Ministry of Health now puts the total suspected cases of microcephaly at 1,761 identified in 422 municipalities in 14 Brazilian states.

Brazil microcephaly update:
Nearly 1800 suspected cases, Zika virus related microcephaly protocol published
Outbreak New Today – Robert Herriman – 8 December 2015

European Centre for Disease Prevention and Control

The increase in congenital microcephaly observed in Brazil is of concern.

Its emergence a few months after the introduction of Zika virus (ZIKV) infection into the country raises questions about the possible role of the infection in congenital microcephaly.

There is currently only ecological evidence of an association between the two events.

Rapid risk assessment: Microcephaly in Brazil potentially linked to the Zika virus epidemic European Centre for Disease Prevention and Control – 24 November 2015

Click to access zika-microcephaly-Brazil-rapid-risk-assessment-Nov-2015.pdf

Zika virus is transmitted by daytime-active mosquitoes and has been isolated from a number of species in the genus Aedes, such as A. aegypti, and arboreal mosquitoes such as A. africanus, A. apicoargenteus, A. furcifer, A. hensilli, A. luteocephalus, and A. vitattus.

Studies show that the extrinsic incubation period in mosquitoes is about 10 days.

Zika virus can migrate between humans through sexual contact and it can also cross the placenta, affecting an unborn fetus.

A mother already infected with Zika virus near the time of delivery can pass on the virus to her newborn around the time of birth, but this is rare.

In December 2015, it was suspected that a transplacental infection of the fetus may lead to microcephaly and brain damage.

Zika fever is an illness caused by the Zika virus, a member of the genus Flavivirus. Symptoms are similar to other Flaviviruses such as Dengue fever or the Alphavirus Chikungunya but are milder in form and usually last four to seven days.

Most cases (60–80%) are asymptomatic.

The main clinical symptoms in symptomatic patients are low-grade fever, conjunctivitis, transient arthritis/arthralgia (mainly in the smaller joints of the hands and feet) and maculopapular rash that often starts on the face and then spreads throughout the body.

In general the disease symptoms are mild and short-lasting (2–7 days).

Health officials studying the 2015 Brazilian outbreak suspect that the disease may undergo mother-to-child transmission in the womb and cause microcephaly, a birth defect.

Microcephaly is a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age.

Babies with microcephaly often have smaller brains that might not have developed properly.


Facts about Microcephaly
Division of Birth Defects and Developmental Disabilities, NCBDDD,
Centers for Disease Control and Prevention

Given these “concerns” it is surprising that Oxitec and Piracicaba City Hall have decided to expand the Friendly Aedes aegypti Project.

Intrexon Corporation, a leader in synthetic biology, announced its subsidiary Oxitec and Piracicaba City Hall have expanded the ‘Friendly Aedes aegypti Project’ in Piracicaba, Brazil following strong results for controlling the Ae. aegypti mosquito population, the primary vector for dengue, chikungunya and Zika virus outbreaks around the world.

Oxitec to expand ‘Friendly Aedes aegypti Project’ in Brazil
Outbreak New Today – Posted by Press Release – 20 January 2016

However, in statistics correlation does not imply causation.

Zika: a rare benign virus suddenly turns nasty, and heads for the US
Some of the headlines have focused on the apparent association between Zika infection in pregnant women and the birth of babies with small brains – a condition known as microcephaly.

This association is still largely circumstantial, but if true would be extremely alarming.

Zika has also apparently changed its behaviour in other ways, spreading faster, spreading sexually, and also lumbering some survivors with the nasty post-viral Guillain-Barré Syndrome.

Although GBS can be fatal, the worst GBS manifestation in recovered Zika patients so far has been a partial temporary paralysis.

Zika: a rare benign virus suddenly turns…
WeCare – Derek Gatherer, Lecturer, Lancaster University – 25 Jan 2016

Therefore, only time and more research will establish whether the genetically modified “Friendly Aedes aegypti” is:

a) A “friendly” and effective mechanism for insect and disease control
b) A biological hazard that can be employed by eugenicists and the military.

For more information and comments see:

The Anti Media – Claire Bernish

Reposted on Zero Hedge

UPDATE 6 Feb 2016
A re-examination of the microcephaly cases in Brazil suggests there is no connection with the Zika virus.

Of the cases examined so far, 404 have been confirmed as having microcephaly.

Only 17 of them tested positive for the Zika virus.

Birth Defects in Brazil May Be Over-Reported Amid Zika Fears
New York Time – Vinod Sreeharsha – 3 Feb 2016

Jon Rappoport and James Corbett provide some very interesting insights.

Interview 1134 – Jon Rappoport Dissects the Zika Hype – 6 Feb 2016
The Corbett Report

UPDATE 17 Feb 2016

According to the Physicians in Crop-Sprayed Towns (PCST), a chemical larvicide that produces malformations in mosquitoes was injected into Brazil’s water supplies in 2014 in order to stop the development of mosquito larvae in drinking water tanks.

The chemical, which is known as Pyriproxyfen, was used in a massive government-run program tasked to control the mosquito population in the country.
“Malformations detected in thousands of children from pregnant women living in areas where the Brazilian state added pyriproxyfen to drinking water is not a coincidence,” the PCST wrote in the report.

Larvicide Manufactured By Sumitomo, Not Zika Virus, True Cause Of Brazil’s Microcephaly Outbreak: Doctors
Tech Times – Alyssa Navarro – 14 February 2016

Gallery | This entry was posted in Medicine, Science. Bookmark the permalink.

2 Responses to Genetically Modified Insects

  1. rishrac says:

    There is a new way of controlling insects. It is possible to program certain traits that reproduce generation after generation with gene drivers. Of course that opens a whole new Pandora’s box.

  2. malagabay says:

    Brazil Experiment May Have Accidentally Created Genetically-Modified Super Mosquitos
    Zero Hedge – Tyler Durden – 17 Sept 2019

    During a 27-month experiment aimed at curbing the spread of Yellow Fever, Dengue, Zika and other mosquito-borne diseases, approximately 450,000 male “OX513A” mosquitos modified by UK biotech company Oxitec were released into the wild in 2013.

    Females who mate with the designer mosquitos produce non-viable offspring, while Oxitec said that the man-made modifications wouldn’t make it into the local insect population.


    Around the 18-month mark, the number of mosquitos returned to pre-release levels, while females opted to avoid mating with the weaker, genetically-modified mosquitos at the same time in a phenomenon known as “mating discrimination” according to Powell.

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