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Bacillus thuringiensis is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well on leaf surfaces, aquatic environments, animal feces, insect-rich environments, and flour mills and grain-storage facilities. It has also been observed to parasitize other moths such as Cadra calidella—in laboratory experiments working with C. calidella, many of the moths were diseased due to this parasite.
Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both traits are now in use in multiple countries. GM maize has also caused controversy with respect to possible health effects, impact on other insects and impact on other plants via gene flow. One strain, called Starlink, was approved only for animal feed in the US but was found in food, leading to a series of recalls starting in 2000.
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to be a major factor behind the increase in the 20th-century's agricultural productivity. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans and/or animals; some become concentrated as they spread along the food chain.
Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of integrated pest management (IPM) programs.
Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. If a pest has resistance then the pesticide lacks efficacy – efficacy and resistance are inversely related.
Bacillus thuringiensis serotype israelensis (Bti) is a group of bacteria used as biological control agents for larvae stages of certain dipterans. Bti produces toxins which are effective in killing various species of mosquitoes, fungus gnats, and blackflies, while having almost no effect on other organisms. The major advantage of B. thuringiensis products is that they are thought to affect few non-target species. However, even though Bti may have minimal direct effects on non-target organisms, it may potentially be associated with knock-on effects on food webs and other ecosystem properties, including biodiversity and ecosystem functioning.
Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl) channels. This causes hyperexcitation of contaminated insects' nerves and muscles. Fipronil's specificity towards insects is believed to be due to its greater binding affinity to the GABAA receptors of insects, than to those of mammals, and to its action on GluCl channels, which do not exist in mammals. As of 2017, there did not appear to be significant resistance among fleas to fipronil.
A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seen as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.
Trichogramma is a genus of minute polyphagous wasps that are endoparasitoids of insect eggs. Trichogramma is one of around 80 genera from the family Trichogrammatidae, with over 200 species worldwide.
A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes. Larvicides may be contact poisons, stomach poisons, growth regulators, or (increasingly) biological control agents.
Bt cotton is a genetically modified pest resistant plant cotton variety, which produce an insecticide to combat bollworm.
Lysinibacillus sphaericus is a Gram-positive, mesophilic, rod-shaped bacterium commonly found on soil. It can form resistant endospores that are tolerant to high temperatures, chemicals and ultraviolet light and can remain viable for long periods of time. It is of particular interest to the World Health Organization due to the larvicide effect of some strains against two mosquito genera, more effective than Bacillus thuringiensis, frequently used as a biological pest control. L. sphaericus cells in a vegetative state are also effective against Aedes aegypti larvae, an important vector of yellow fever and dengue viruses.
Delta endotoxins (δ-endotoxins) are pore-forming toxins produced by Bacillus thuringiensis species of bacteria. They are useful for their insecticidal action and are the primary toxin produced by Bt maize/corn. During spore formation the bacteria produce crystals of such proteins that are also known as parasporal bodies, next to the endospores; as a result some members are known as a parasporin. The Cyt (cytolytic) toxin group is a group of delta-endotoxins different from the Cry group.
Helicoverpa punctigera, the native budworm, Australian bollworm or Chloridea marmada, is a species of moth in the family Noctuidae. This species is native to Australia. H. punctigera are capable of long-distance migration from their inland Australian habitat towards coastal regions and are an occasional migrant to New Zealand.
The MON 810 corn is a genetically modified maize used around the world. It is a Zea mays line known as YieldGard from the company Monsanto. This plant is a genetically modified organism (GMO) designed to combat crop loss due to insects. There is an inserted gene in the DNA of MON 810 which allows the plant to make a protein that harms insects that try to eat it. The inserted gene is from the Bacillus thuringiensis which produces the Bt protein that is poisonous to insects in the order Lepidoptera, including the European Corn Borer.
Naled (Dibrom) is an organophosphate insecticide. Its chemical name is dimethyl 1,2-dibromo-2,2-dichloroethylphosphate.
Trichogramma brassicae is a species of parasitoid wasps from the Trichogrammatidae family. It mainly parasitizes Lepidopteran hosts in agricultural fields. They are entomaphagous parasitoids that deposit their own eggs inside the host's eggs, consuming the host egg material and emerging upon full development. They are a common biological control species that have been used commercially since the late 1970s. Inundative releases of T. brassicae, recently, can be done by means of drones and integrated control with Bacillus thuringiensis subs. kurstaki were demonstrated effective as chemical insecticide treatments and of course without negative environmental side effects.
Cry6Aa is a toxic crystal protein generated by the bacterial family Bacillus thuringiensis during sporulation. This protein is a member of the alpha pore forming toxins family, which gives it insecticidal qualities advantageous in agricultural pest control. Each Cry protein has some level of target specificity; Cry6Aa has specific toxic action against coleopteran insects and nematodes. The corresponding B. thuringiensis gene, cry6aa, is located on bacterial plasmids. Along with several other Cry protein genes, cry6aa can be genetically recombined in Bt corn and Bt cotton so the plants produce specific toxins. Insects are developing resistance to the most commonly inserted proteins like Cry1Ac. Since Cry6Aa proteins function differently than other Cry proteins, they are combined with other proteins to decrease the development of pest resistance. Recent studies suggest this protein functions better in combination with other virulence factors such as other Cry proteins and metalloproteinases.>
Trichogramma japonicum is a minute wasp parasitoid from the Trichogrammatidae family in the order Hymenoptera. T. japonicum parasitizes the eggs of many pest species, especially Lepidoptera found in many monocultures. They are entomophagous parasitoids that deposit their eggs inside the host species' egg, consuming the host egg material and emerging from the egg once development is complete. T. japonicum can be found naturally in rice ecosystems, but are dispersed commercially to many monocultures as a biological control. The mitochondrial genomes of T. japonicum are significantly rearranged when comparing it to related insects.
Cry34Ab1 is one member of a binary Bacillus thuringiensis (Bt) crystal protein set isolated from Bt strain PS149B1. The protein exists as a 14 kDa aegerolysin that, in presence of Cry35Ab1, exhibits insecticidal activity towards Western Corn Rootworm. The protein has been transformed into maize plants under the commercialized events 4114 (DP-ØØ4114-3) by Pioneer Hi-Bred and 59122 (DAS-59122-7) by Dow AgroSciences. These events have, in turn, been bred into multiple trait stacks in additional products.
References
- ↑ Bulla LAJ, Davidson LI, Kramer KJ, Jones BL. (1979). "Purification of the insecticidal toxin from the parasporal crystal of Bacillus thuringiensis subsp. kurstaki". Biochem Biophys Res Commun. 91 (3): 1123–1130. doi:10.1016/0006-291x(79)91997-1. PMID 526269.
- ↑ Adang, MJ; Staver, MJ; Rocheleau, TA; Leighton, J; Barker, RF; Thompson, DV (1985). "Characterized full-length and truncated plasmid clones of the crystal protein of Bacillus thuringiensis subsp. kurstaki HD-73 and their toxicity to Manduca sexta". Gene. 36 (3): 289–300. doi:10.1016/0378-1119(85)90184-2. PMID 3000881.
- ↑ Choma, Christin; Surewicz, Witold; Carey, Paul; Pozsgay, Marianne; Kaplan, Harvey (February 1990). "Secondary structure of the entomocidal toxin from Bacillus thuringiensis subsp. kurstaki HD-73". Journal of Protein Chemistry. 9 (1): 87–94. doi:10.1007/BF01024989. PMID 2340079. S2CID 24749422.
- ↑ European Food Safety Authority (2012). "Conclusion on the peer review of the pesticide risk assessment of the active substance Bacillus thuringiensis subsp. kurstaki (strains ABTS 351, PB 54, SA 11, SA 12, EG 2348)". EFSA Journal. 10 (2): 66 pp. doi: 10.2903/j.efsa.2012.2540 .
- ↑
- Amichot, Marcel; Curty, Christine; Benguettat-Magliano, Olivia; Gallet, Armel; Wajnberg, Eric (February 2016). "Side effects of Bacillus thuringiensis var. kurstaki on the hymenopterous parasitic wasp Trichogramma chilonis". Environmental Science and Pollution Research. 23 (4): 3097–3103. doi:10.1007/s11356-015-5830-7. PMID 26590060. S2CID 19972084.
- Amichot, Marcel; Joly, Pierre; Martin-Laurent, Fabrice; Siaussat, David; Lavoir, Anne-Violette (2018-10-10). "Biocontrol, new questions for Ecotoxicology?" (PDF). Environmental Science and Pollution Research . European Chemical Society Division of Chemistry and the Environment (Springer). 25 (34 ECOTOX, new questions for terrestrial and aquatic ecotoxicology): 33895–33900. doi:10.1007/s11356-018-3356-5. ISSN 0944-1344. PMID 30306444. S2CID 52956673. HAL Id: 02051049.
- Coll, Moshe; Wajnberg, Eric (25 August 2017). Environmental Pest Management: Challenges for Agronomists, Ecologists, Economists and Policymakers. Hoboken, NJ. pp. xvi+432. doi:10.1002/9781119255574.CH6. ISBN 978-1-119-25557-4. OCLC 995357237. S2CID 135321067. ISBN 978-1-119-25557-4.: 133
- ↑ Tapp, H; Stotzky, G (15 April 1998). "Persistence of the insecticidal toxin from Bacillus thuringiensis subsp. kurstaki in soil". Soil Biology and Biochemistry. 30 (4): 471–476. doi: 10.1016/S0038-0717(97)00148-X .