Alarvicide(alternativelylarvacide) is aninsecticidethat is specifically targeted against thelarvallife stage of aninsect.Their most common use is againstmosquitoes.Larvicides may becontact poisons,stomach poisons, growth regulators, or (increasingly)biological controlagents.
Biological agents
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The biological control agentBacillus thuringiensis,also known asBt,is abacterialdisease specific toLepidopterancaterpillars.Bacillus thuringiensis israelensis,also known asBti,andBacillus sphaericus,which affect larval mosquitoes and somemidges,have come into increasing use in recent times.[1][2]
BtiandB. sphaericusare both naturally occurring soil bacterium registered as larvicides under the names Bactivec, Bacticide, Aquabac, Teknar, Vectobac, LarvX, and VectoLex CG. Typically in granular form, pellets are distributed on the surface ofstagnant waterlocations. When the mosquito larvae ingest the bacteria, crystallized toxins are produced that destroy the digestive tract, resulting in death. These larvicides will last only a few weeks in water and pose no danger to humans, non-targeted animal species, or the environment when used according to directions.
Chemical agents
editMethopreneis an insect growth regulator agent that interrupts the growth cycle of insect larvae, preventing them from developing beyond thepupastage. MetaLarv and Altosid are products containing S-methoprene as the active ingredient. They are usually applied to larger bodies of water in the form of time-release formulations that can last from one to five months. Use of this larvicide does not pose an unreasonable health risks to humans or other wildlife, and it will not leach into the ground water supply. Methoprene is moderately toxic to some fish,shrimp,lobster,andcrayfish,and highly toxic to some fish and freshwater invertebrates; itbioaccumulatesin fish tissues.[3]
Temephos,marketed as Abate and ProVect, is anorganophosphatewhich prevents mosquito larvae from developing resistance to bacterial larvicides. Due to the small amount needed and the fast rate that temephos breaks down in water, this type of larvicide does not pose an unreasonable health risk to humans, but at large doses it can cause nausea or dizziness. Similarly, there is not a large risk to terrestrial species, but there is a toxic concern for non-targeted aquatic species. Therefore, temephos should be limited only to sites where less hazardous larvicides are ineffective and with intervals between applications.[citation needed]
Copperis also known for its larvicidal properties, and has been tested in field settings to determine its effectiveness and practicality for mosquito control.[4][5]
Acoustic larvicide
editSound energy transmitted into water at specific frequencies cause larvae air bladders to instantly rupture, severely damaging internal tissues causing death or latent effects prohibiting further maturity.[6]
Other techniques
editLarviciding techniques can also include the addition of surface films to standing water to suffocate mosquito larvae, or thegenetic modificationof plants so that they naturally produce a larvicide in plant tissues.[citation needed]
Research on botanical oils has foundneem oilto be larvicidal.[citation needed]
Larvicidal activity of neem oil (Azadirachta indica) formulation against mosquitoes. Median lethal concentration (LC50) of the formulation against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti was found to be 1.6, 1.8 and 1.7 ppm respectively. The formulation also showed 95.1% and 99.7% reduction of Aedes larvae on day 1 and day 2 respectively; thereafter 100% larval control was observed up to day 7.[7][8]
See also
editReferences
editThis articleneeds additional citations forverification.(July 2007) |
- ^Madigan MT, Martinko JM, eds. (2005).Brock Biology of Microorganisms(11th ed.). Prentice Hall.ISBN978-0-13-144329-7.[page needed]
- ^du Rand, Nicolette (July 2009).Isolation of Entomopathogenic Gram Positive Spore Forming Bacteria Effective Against Coleoptera(PhD Thesis). Pietermaritzburg, South Africa: University of KwaZulu-Natal.hdl:10413/1235.[page needed]
- ^"Methoprene: General Fact Sheet".National Pesticide Information Center.Retrieved12 February2016.
- ^Reza, Mohamad; Ilmiawati, Cimi; Matsuoka, Hiroyuki (2016)."Application of copper-based ovitraps in local houses in West Sumatra, Indonesia: a field test of a simple and affordable larvicide for mosquito control".Tropical Medicine and Health.44:11.doi:10.1186/s41182-016-0007-8.PMC4940706.PMID27433130.
- ^Rahman, Afroja; Pittarate, Sarayut; Perumal, Vivekanandhan; Rajula, Julius; Thungrabeab, Malee; Mekchay, Supamit; Krutmuang, Patcharin (2022)."Larvicidal and Antifeedant Effects of Copper Nano-Pesticides against Spodoptera frugiperda (J.E. Smith) and Its Immunological Response".Insects.13(11): 1030.doi:10.3390/insects13111030.PMC9692944.PMID36354854.
- ^Nyberg, H. J.; Muto, K. (2020-02-11)."Acoustic tracheal rupture provides insights into larval mosquito respiration".Scientific Reports.10(1): 2378.Bibcode:2020NatSR..10.2378N.doi:10.1038/s41598-020-59321-8.PMC7016133.PMID32051479.
- ^Mulla MS, Su T (1999). "Activity and biological effects of neem products against arthropods of medical and veterinary importance".Journal of the American Mosquito Control Association.15(2): 133–52.PMID10412110.
- ^"Pest Control Sydney".Retrieved25 February2021.