Anopheles gambiae

The Anopheles gambiae complex or Anopheles gambiae sensu lato was recognized as a species complex only in the 1960s. The A. gambiae complex consists of:

• Anopheles arabiensis
• Anopheles bwambae
• Anopheles melas
• Anopheles merus
• Anopheles quadriannulatus[4][5]
• Anopheles gambiae sensu stricto (s.s.)[6]
• Anopheles coluzzii
• Anopheles amharicus

The individual species of the complex are morphologically difficult to distinguish from each other, although it is possible for larvae and adult females. The species exhibit different behavioural traits. For example, Anopheles quadriannulatus is both a saltwater and mineralwater species. A. melas and A. merus are saltwater species, while the remainder are freshwater species.[7] Anopheles quadriannulatus generally takes its blood meal from animals (zoophilic), whereas Anopheles gambiae sensu stricto generally feeds on humans, i.e. is considered anthropophilic. Identification to the individual species level using the molecular methods of Scott et al. (1993)[8] can have important implications in subsequent control measures.

An. gambiae sensu stricto (s.s.) has been discovered to be currently in a state of diverging into two different species—the Mopti (M) and Savannah (S) strains—though as of 2007, the two strains are still considered to be a single species.[9][10]

The mechanism of species recognition appears to be sounds emitted by the wings and identified by Johnston's organ.[11]

An. gambiae s.s. genomes have been sequenced three times, once for the M strain, once for the S strain, and once for a hybrid strain.[9][10] Currently, ~90 miRNA have been predicted in the literature (38 miRNA officially listed in miRBase) for An. gambiae s.s. based upon conserved sequences to miRNA found in Drosophila. Holt et al., 2002 and Neafsey et al., 2016 find transposable elements to be ~13% of the genome, similar to Drosophila melanogaster (also in Diptera).[12] However they find the proportion of TE types to be very different from D. melanogaster with approximately the same composition of long terminal repeat retrotransposons, non-long terminal repeat retrotransposons and DNA transposons.[12] These proportions are believed to be representative of the genus.[12]

The genetics and genomics of sex chromosomes have been discovered and studied by Windbichler et al., 2007 and Galizi et al., 2014 (a Physarum polycephalum homing endonuclease which destroys X chromosomes), Windbichler et al., 2008 and Hammond et al., 2016 (methods to reduce the female population), Windbichler et al., 2011 (trans from yeast), Bernardini et al., 2014 (a method to increase the male population), Kyrou et al., 2018 (a female necessary exon and a homing endonuclease to drive it), Taxiarchi et al., 2019 (sex chromosome dynamics in general) and Simoni et al., 2020 (an X chromosome destroying site specific nuclease).[13] See § Gene drive below for their applications.

An. gambiae has a high degree of polymorphism. This is especially true in the cytochrome P450s, Wilding et al., 2009 finding 1 single nucleotide polymorphism (SNP)/26 base pairs. This species has the highest amount of polymorphism in the CYPs of any insect known, much tending to be found in "scaffolds" that are found only in particular subpopulations. These are termed "dual haplotype regions" by Holt et al., 2002 who sequenced the PEST strain.[14]^: 241

In common with many chromosomes, An. gambiae codes for spindle and kinetochore-associated proteins. Hanisch et al., 2006 locate AgSka1, the spindle and kinetochore-associated protein 1 gene, at EAL39257.[15]

The entire Culicidae family may or may not conserve epigenetic mechanisms – as of 2012 this remains unresolved.[16] Toward answering this question, Marhold et al., 2004 compare their own previous work in Drosophila melanogaster against new sequences of D. pseudoobscura and An. gambiae.[16] They find all three do share the DNA methylation enzyme DNMT2 (DmDNMT2, DpDNMT2, and AgDNMT2).[16] This suggests all Diptera may conserve an epigenetic system employing Dnmt2.[16]

Hosts include Bos taurus, Capra hircus, Ovis aries and Sus scrofa.[17]

Parasites include Plasmodium berghei (for which it also serves as a vector),[18][19][20] and the bioinsecticides/entomopathogenic fungi Metarhizium robertsii[18] and Beauveria bassiana.[18] All three of these parasites combine with insecticides to reduce fitness – see § Insecticides below.[18] CRISPR/Cas9 and U6-gRNA are increasingly (as of 2020) being used together for knockout experiments in mosquitoes.[20] Dong et al., 2018 develops and presents a new U6-gRNA+Cas9 technique in An. gambiae, and utilizes it to knock out fibrinogen related protein 1 (FREP1), thereby severely reducing infection of the mosquito by P. berghei and P. falciparum.[20] However this also demonstrates the centrality of FREP1 to the insect's success, impairing all measured activities across all life stages.[20] Yang et al., 2020 uses the Dong method to do the same with mosGILT, also severely reducing Plasmodium infection of the mosquito but also finding a vital life process is impaired, in mosGILT's case ovary development.[20]

Fecundity of An. gambiae depends on the detoxification of reactive oxygen species (ROS) by catalase.[21] Reduction in catalase activity significantly reduces reproductive output of female mosquitoes, indicating that catalase plays a central role in protecting oocytes and early embryos from ROS damage.[21]

An. gambiae invaded northeastern Brazil in 1930, which led to a malaria epidemic in 1938/1939.[22] The Brazilian government assisted by the Rockefeller Foundation in a programme spearheaded by Fred Soper eradicated these mosquitoes from this area. This effort was modeled on the earlier success in eradication of Aedes aegypti as part of the yellow fever control program. The exact species involved in this epidemic has been identified as An. arabiensis.[23]

Kaufmann and Brown 2008 find the An. gambiae adipokinetic hormone (AKH) mobilizes carbohydrates but not lipids. Meanwhile AKH/Corazonin Peptide (ACP) does not mobilize (or inhibit mobilization) of either. Mugumbate et al., 2013 provides in solution and membrane bound structures from a nuclear magnetic resonance investigation.[24]

• "Anopheles gambiae". VectorBase. Archived from the original on 2019-01-27. Retrieved 2013-07-12.
• View the anoGam1 genome assembly in the UCSC Genome Browser.
• DiArk