![Drosophila melanogaster - front (aka)](https://upload.wikimedia.org/wikipedia/commons/5/50/Drosophila_melanogaster_-_front_%28aka%29.jpg)
A genetically modified (GM) insect is an
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
that has been
genetically modified
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of Genetic engineering techniques, technologies used to change the gene ...
, either through
mutagenesis
Mutagenesis () is a process by which the genetic information of an organism is changed by the production of a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using la ...
, or more precise processes of
transgenesis
Gene delivery is the process of introducing foreign genetic material, such as DNA or RNA, into host cells. Gene delivery must reach the genome of the host cell to induce gene expression. Successful gene delivery requires the foreign gene deli ...
, or
cisgenesis
Cisgenesis is a product designation for a category of genetically engineered plants. A variety of classification schemes have been proposed that order genetically modified organisms based on the nature of introduced genotypical changes, rather tha ...
. Motivations for using GM insects include biological research purposes and genetic
pest management
Pest control is the regulation or management of a species defined as a pest (organism), pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage don ...
. Genetic pest management capitalizes on recent advances in biotechnology and the growing repertoire of
sequenced genomes in order to control pest populations, including insects. Insect genomes can be found in genetic databases such as NCBI, and databases more specific to insects such as FlyBase, VectorBase, and BeetleBase. There is an ongoing initiative started in 2011 to sequence the genomes of 5,000 insects and other arthropods called the i5k. Some
Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
(e.g.
monarch butterflies
The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. It ...
and
silkworms
The domestic silk moth (''Bombyx mori''), is an insect from the moth family Bombycidae. It is the closest relative of ''Bombyx mandarina'', the wild silk moth. The silkworm is the larva or caterpillar of a silk moth. It is an economically imp ...
) have been genetically modified in nature by the wasp
bracovirus
''Bracovirus'' is a genus of viruses, in the family ''Polydnaviridae''. Bracoviruses are an ancient symbiotic virus contained in parasitic braconid wasps that evolved off of the ''nudivirus'' about 190 million years ago and has been evolving at ...
.
Types of genetic pest management
The
sterile insect technique
The sterile insect technique (SIT) is a method of biological insect control, whereby overwhelming numbers of sterile insects are released into the wild. The released insects are preferably male, as this is more cost-effective and the females ma ...
(SIT) was developed conceptually in the 1930s and 1940s and first used in the environment in the 1950s. SIT is a control strategy where male insects are sterilized, usually by irradiation, then released to mate with wild females. If enough males are released, the females will mate with mostly sterile males and lay non-viable eggs. This causes the population of insects to crash (the abundance of insects is extremely diminished), and in some cases can lead to local eradication. Irradiation is a form of mutagenesis which causes random mutations in DNA.
Release of Insects carrying Dominant Lethals (RIDL)
Release of Insects carrying Dominant Lethals or RIDL is a control strategy using genetically engineered insects that have (carry) a lethal gene in their genome (an organism's DNA).
Lethal genes cause death in an organism, and RIDL genes only kill young insects, usually larvae or pupae. Similar to how inheritance of brown eyes is dominant to blue eyes, this lethal gene is dominant so that all offspring of the RIDL insect will also inherit the lethal gene. This lethal gene has a molecular on and off switch, allowing these RIDL insects to be reared. The lethal gene is turned off when the RIDL insects are mass reared in an insectary, and turned on when they are released into the environment. RIDL males and females are released to mate with wild males and their offspring die when they reach the larval or pupal stage because of the lethal gene. This causes the population of insects to crash. This technique is being developed for some insects and for other insects has been tested in the field. It has been used in the Grand Cayman Islands, Panama, and Brazil to control the mosquito vector of dengue, ''Ae. aegypti.'' It is being developed for use in
diamondback moth
The diamondback moth (''Plutella xylostella''), sometimes called the cabbage moth, is a moth species of the family Plutellidae and genus '' Plutella''. The small, grayish-brown moth sometimes has a cream-colored band that forms a diamond along ...
(''Plutella xylostella''), medfly (''
Ceratitis capitata
''Ceratitis capitata'', commonly known as the Mediterranean fruit fly or medfly, is a yellow-and-brown fly native to sub-Saharan Africa. It has no near relatives in the Western Hemisphere and is considered to be one of the most destructive frui ...
'') and
olive fly (''Bactrocera oleae'').
Incompatible Insect Technique (IIT)
''
Wolbachia
''Wolbachia'' is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproduct ...
''
Maternal Effect Dominant Embryonic Arrest (MEDEA)
X-Shredder
Concerns
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
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
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
''Ceratitis capitata'', commonly known as the Mediterranean fruit fly or medfly, is a yellow-and-brown fly native to sub-Saharan Africa. It has no near relatives in the Western Hemisphere and is considered to be one of the most destructive frui ...
'').
Releases
Oxitec released its genetically modified in various countries, including
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
Grand Cayman
Grand Cayman is the largest of the three Cayman Islands and the location of the territory's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles (121 km) southwest of Little Cayman and 90 miles ( ...
,
Malaysia
Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
,
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
, and the
US.
Modified species
Biological research
* Fruit flies (''
Drosophila melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...
'') are
model organism
A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...
s used in an array of biological disciplines (i.e.
neurobiology
Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...
,
population genetics
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and pop ...
,
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...
,
animal behavior
Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objective ...
,
systematics
Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic tre ...
,
genomics
Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...
, and
development
Development or developing may refer to:
Arts
*Development hell, when a project is stuck in development
*Filmmaking, development phase, including finance and budgeting
*Development (music), the process thematic material is reshaped
* Photograph ...
). Many studies done with ''Drosophila'' species have been foundational in their respective fields, and they remain important models for other organisms, including humans. For example, they have contributed to understanding economically important insects and researching human disease and development. Fruit flies are often preferred over other animals due to their short life cycle, reproduction rate, low maintenance requirements, and amenability to mutagenesis. They are also the model genetic organism for historical reasons, being one of the first model organism and have a high quality completed
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
.
Genetic pest management
* Yellow fever mosquito (''
Aedes aegypti
''Aedes aegypti'', the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its legs ...
'')
* Malaria mosquito (''
Anopheles gambiae
The ''Anopheles gambiae'' complex consists of at least seven morphologically indistinguishable species of mosquitoes in the genus ''Anopheles''. The complex was recognised in the 1960s and includes the most important vectors of malaria in sub- ...
'' and ''
Anopheles stephensi
''Anopheles stephensi'' is a primary mosquito vector of malaria in urban India and is included in the same subgenus as ''Anopheles gambiae'', the primary malaria vector in Africa. ''A. gambiae'' consists of a complex of morphologically identical ...
'')
*
Pink bollworm
The pink bollworm (''Pectinophora gossypiella''; es, lagarta rosada) is an insect known for being a pest in cotton farming. The adult is a small, thin, gray moth with fringed wings. The larva is a dull white caterpillar with eight pairs of legs w ...
(''Pectinophora gossypiella'')
Diamondback moth
![Plutella xylostella2](https://upload.wikimedia.org/wikipedia/commons/3/34/Plutella_xylostella2.jpg)
The diamondback moth's
caterpillar
Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).
As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...
s gorge on cruciferous vegetables such as cabbage, broccoli, cauliflower and kale, globally costing farmers an estimated $5 billion (£3.2 billion) a year worldwide. In 2015, Oxitec developed GM-diamondback moths which produce non-viable female larvae to control populations able to develop resistance to insecticides. The GM-insects were initially placed in cages for field trials. Earlier, the moth was the first crop pest to evolve resistance to
DDT
Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
[ and eventually became resistant to 45 other insecticides.] In Malaysia, the moth has become immune to all synthetic sprays.[ The gene is a combination of DNA from a ]virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's 1 ...
and a bacterium
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. In an earlier study, captive males carrying the gene eradicated communities of non-GM moths. Brood sizes were similar, but female offspring died before reproducing. The gene itself disappears after a few generations, requiring ongoing introductions of GM cultivated males. Modified moths can be identified by their red glow under ultraviolet light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
, caused by a coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...
transgene.[
Opponents claim that the protein made by the synthetic gene could harm non-target organisms that eat the moths. The creators claim to have tested the gene's protein on mosquitoes, fish, beetles, spiders and ]parasitoids
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasi ...
without observing problems. Farmers near the test site claim that moths could endanger nearby farms' organic certification
Organic certification is a certification process for producers of organic food and other organic agricultural products, in the European Union more commonly known as ecological or biological products.Labelling, article 30 o''Regulation (EU) 201 ...
. Legal experts say that national organic standards penalize only deliberate GMO use. The creators claim that the moth does not migrate if sufficient food is available, nor can it survive winter weather.
Mediterranean fruit fly
The Mediterranean fruit fly is a global agricultural pest. They infest a wide range of crops (over 300) including wild fruit, vegetables and nuts, and in the process, cause substantial damage. The company Oxitec has developed GM-males which have a lethal gene that interrupts female development and kills them in a process called "pre-pupal female lethality". After several generations, the fly population diminishes as the males can no longer find mates. To breed the flies in the laboratory, the lethal gene can be "silenced" using the antibiotic tetracycline
Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...
.
Opponents argue that the long-term effects of releasing millions of GM-flies are impossible to predict. Dead fly larvae could be left inside crops. Helen Wallace from Genewatch
The Council for Responsible Genetics (CRG) was a nonprofit NGO with a focus on biotechnology.
History
The Council for Responsible Genetics was founded in 1983 in Cambridge, Massachusetts.
An early voice concerned about the social and ethica ...
, an organisation that monitors the use of genetic technology, stated "Fruit grown using Oxitec's GM flies will be contaminated with GM maggots which are genetically programmed to die inside the fruit they are supposed to be protecting". She added that the mechanism of lethality was likely to fail in the longer term as the GM flies evolve resistance or breed in sites contaminated with tetracycline which is widely used in agriculture.
Legislation
In July 2015, the House of Lords
The House of Lords, also known as the House of Peers, is the Bicameralism, upper house of the Parliament of the United Kingdom. Membership is by Life peer, appointment, Hereditary peer, heredity or Lords Spiritual, official function. Like the ...
(U.K.) Science and Technology Committee launched an inquiry into the possible uses of GM-insects and their associated technologies. The scope of the inquiry is to include questions such as "Would farmers benefit if insects were modified in order to reduce crop pests? What are the safety and ethical concerns over the release of genetically modified insects? How should this emerging technology be regulated?"
Notes and references
See also
* Inherited sterility in insects
* List of sterile insect technique trials
* Insect ecology
Insect ecology is the scientific study of how insects, individually or as a community, interact with the surrounding environment or ecosystem.
Insects play significant roles in the ecology of the world due to their vast diversity of form, functio ...
* Detection of genetically modified organisms
The detection of genetically modified organisms in food or feed is possible by biochemical means. It can either be qualitative, showing which genetically modified organism (GMO) is present, or quantitative, measuring in which amount a certain GMO i ...
External links
Transgenic Fly Virtual Lab - Howard Hughes Medical Institute BioInteractive
*
{{DEFAULTSORT:Genetically Modified Insect
Genetically modified organisms