Genome of the house fly, <i>Musca domestica</i> L., a global vector of diseases with adaptations to a septic environment

Background: Adult house flies, Musca domestica L., are mechanical vectors of more than 100 devastating diseases that have severe consequences for human and animal health. House fly larvae play a vital role as decomposers of animal wastes, and thus live in intimate association with many animal pathogens. Results: We have sequenced and analyzed the genome of the house fly using DNA from female flies. The sequenced genome is 691 Mb. Compared with Drosophila melanogaster, the genome contains a rich resource of shared and novel protein coding genes, a significantly higher amount of repetitive elements, and substantial increases in copy number and diversity of both the recognition and effector components of the immune system, consistent with life in a pathogen-rich environment. There are 146 P450 genes, plus 11 pseudogenes, in M. domestica, representing a significant increase relative to D. melanogaster and suggesting the presence of enhanced detoxification in house flies. Relative to D. melanogaster, M. domestica has also evolved an expanded repertoire of chemoreceptors and odorant binding proteins, many associated with gustation. Conclusions: This represents the first genome sequence of an insect that lives in intimate association with abundant animal pathogens. The house fly genome provides a rich resource for enabling work on innovative methods of insect control, for understanding the mechanisms of insecticide resistance, genetic adaptation to high pathogen loads, and for exploring the basic biology of this important pest. The genome of this species will also serve as a close out-group to Drosophila in comparative genomic studies

Multiple Origins of <em>kdr-type</em> Resistance in the House Fly, <em>Musca domestica</em>

<div><p>Insecticide resistance is a model phenotype that can be used to investigate evolutionary processes underlying the spread of alleles across a global landscape, while offering valuable insights into solving the problems that resistant pests present to human health and agriculture. Pyrethroids are one of the most widely used classes of insecticides world-wide and they exert their toxic effects through interactions with the voltage-sensitive sodium channel (Vssc). Specific mutations in <em>Vssc</em> (<em>kdr</em>, <em>kdr-his</em> and <em>super-kdr</em>) are known to cause resistance to pyrethroid insecticides in house flies. In order to determine the number of evolutionary origins of <em>kdr</em>, <em>kdr-his</em> and <em>super-kdr</em>, we sequenced a region of <em>Vssc</em> from house flies collected in the USA, Turkey and China. Our phylogenetic analysis of <em>Vssc</em> unequivocally supports the hypothesis of multiple independent origins of <em>kdr</em>, <em>super-kdr</em> and <em>kdr-his</em> on an unprecedented geographic scale. The implications of these evolutionary processes on pest management are discussed.</p> </div

Resistance mechanisms, patterns of inheritance, evolutionary origins and prevalence of mutations conferring insecticide resistance.

*<p>“While phylogenetic analysis of these haplotypes suggests that the Asp137 and Leu251 mutations each arose at least twice, evidence for recombination was detected across the region, therefore single origins for these resistance mutations cannot be ruled out.” <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052761#pone.0052761-Newcomb1" target="_blank">[9]</a>.</p><p>∧The number of species/subspecies of B. tabaci has recently been questioned <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052761#pone.0052761-Boykin1" target="_blank">[46]</a>. If the results above are from different species then findings of multiple origins of resistance need to be interpreted with care.</p

<i>Vssc</i> haplotypes found in house fly populations that share the same intron sequence.

<p>Haplotypes in the same column have identical intron sequences. Haplotypes within a column are differentiated solely by the 1014/918 codons. Letters above each column are arbitrary and have no nomenclature significance.</p

Maximum-likelihood phylogeny of <i>Vssc</i> alleles/haplotypes in house flies.

<p>Tree is unrooted, and is shown here with a mid-point root for visualization only. Susceptible haplotypes are represented by <i>v</i>+number. Numbers at nodes represent the bootstrap values (%); only bootstrap values greater than 50% are shown.</p