The detection and significance of emerging insecticide resistance in mosquitoes

Abstract

Mosquito-borne arboviruses are increasing in incidence around the world. Australia enjoys some protection from pests and diseases afforded by its geographic isolation coupled with strict biosecurity control at its borders. However, as the volume of global trade, travel and transport expands, risk of exotic incursions to Australia is increasing. Detection of foreign mosquitoes at airports and seaports around Australia is becoming commonplace. The Asian tiger mosquito, Aedes albopictus, which has expanded its range throughout Europe and the Americas1, has not become established in mainland Australia, but is encountered as an exotic incursion2. The yellow fever mosquito and dengue vector, Aedes. aegypti, occurs naturally in northern Queensland, but is also captured at Australia’s ports on a recurrent basis as an incursion from overseas3. Although Ae. aegypti is established in Australia, its detection as an incursion is still cause for concern. Apart from the possibility that invasive mosquitoes will carry exotic arboviruses, genetic characteristics of a foreign insect population can be very different from those observed in local mosquitoes, particularly in terms of insecticide resistance. Our recent research has shown that invading mosquitoes from overseas carry insecticide resistance alleles not found in Australia4 and our development of a global genomic database is helping us to pinpoint their source.

Tracking genetic invasions: Genome‐wide single nucleotide polymorphisms reveal the source of pyrethroid‐resistant Aedes aegypti (yellow fever mosquito) incursions at international ports

“…Within most of the non-Australian Ae. aegypti reference populations in this study, there is considerable diversity in resistance genotypes (Endersby-Harshman et al, 2018;unpublished data), with populations made up of homozygotes with theoretically strong resistance, susceptible wild-type homozygotes and heterozygotes of varying resistance status. Our finding that all incursive mosquitoes from international sources had alleles associated with resistance to Type I pyrethroids, and that 82.6% were likely to have displayed strong levels of resistance, suggests that aircraft disinsection may be successfully eliminating pyrethroid-susceptible mosquitoes, while pyrethroid resistance may be permitting others to survive and reach the Australian and New Zealand borders.…”

“…aegypti (Endersby-Harshman et al, 2017), it is common in Ae. aegypti populations globally (Endersby-Harshman, Weeks, & Hoffmann, 2018;Ranson, Burhani, Lumjuan, & Black, 2010;Smith, Kasai, & Scott, 2016). Point mutations at the Vssc gene can confer target-site knockdown resistance to synthetic pyrethroids in a broad range of insects (Scott et al, 2013;Scott, Yoshimizu, & Kasai, 2015;Seong et al, 2010) including Ae.…”

Origin of resistance to pyrethroids in the redlegged earth mite (Halotydeus destructor) in Australia: repeated local evolution and migration

“…Conversely, if resistance persists despite periods when there is no local application of pesticides, immigration of resistant individuals may play an important role in the persistence of resistance and the management of pesticide applications in regions away from target areas may need to be considered. In regions where resistance is absent, it becomes particularly important to reduce the risk of inadvertent importation of resistance genes, as in Aedes aegypti and Aedes albopictus …”

Tracking genetic invasions: genome-wide SNPs reveal the source of pyrethroid-resistantAedes aegypti(yellow fever mosquito) incursions at international ports

“…aegypti (Endersby-Harshman et al, 2017), it is common in Ae. aegypti populations globally (Endersby-Harshman, Weeks, & Hoffmann, 2018;Ranson, Burhani, Lumjuan, & Black, 2010;L. B. Smith, Kasai, & Scott, 2016).…”