Laboratory rearing of Anopheles arabiensis: impact on genetic variability and implications for Sterile Insect Technique (SIT) based mosquito control in northern Sudan

Abstract

BackgroundMosquito colony populations often show significant changes in their population genetic make-up compared to the field populations that were used as founding source. Most of the changes that have been reported are indicators of depletion in the overall genetic diversity of the colony populations. The Sterile Insect Techniques programme of mosquito control that is underway in Northern Sudan uses sterilized males produced from a laboratory-maintained colony population. The genetic diversity of an advanced generation of this colony population was quantitatively assessed and compared to the field population from which the colony was derived.Methods Anopheles arabiensis mosquito samples from the 13th generation of the colony, and from the locality that was the source of the first generation of the colony, were genotyped at 11 microsatellite loci distributed throughout the species’ genome. Standard population genetic analyses were carried out to quantify and compare their population genetic make-up and diversities.ResultsThe colony samples showed significant reduction in the total number of alleles, the numbers of rare and private alleles, and the fractions of heterozygote individuals at all the loci. The pattern of change is consistent with the expected effect of the use of a small number of mosquitoes when the colony was established. Departure from Hardy–Weinberg equilibrium in the direction of homozygote excess was observed at some loci and attributed to the presence of null-alleles.ConclusionsThis study highlights the need for broad sampling when initiating colony populations and for ongoing assessment of the population genetic make-up of colony populations. Previous assessments of survivorship, dispersive behaviour and swarm formation indicate that the inbreeding and reduced genetic variability reported in this study may not have had direct fitness consequences yet. However, noting the lessons learned in other SIT programmes about the impact of colonization on male sexual behaviour and longevity, as well as other inbreeding related adverse effects, a systematic investigation of these potential effects is recommended because they have direct impact on the ultimate success of the programme.

A low-cost, battery-powered acoustic trap for surveilling male Aedes aegypti during rear-and-release operations

“…Finally, as Aedes rear and release programs expand their efforts to control vector populations (e.g. Oxitec [ 13 ], Verily Debug Project [ 11 ], MosquitoMate [ 12 ], IAEA [ 9 , 14 ]), improved monitoring tools are needed for cheap and accurate male-release tracking. Although the Sound-GAT allows for accurate, low-cost monitoring of male Ae .…”

“…Programs focusing on population suppression through the release of Wolbachia- infected (e.g. Verily Debug Project [ 11 ] and MosquitoMate [ 12 ]), genetically modified (Oxitec [ 13 ]) or irradiated males (IAEA [ 9 , 14 ]), require the ability to monitor wild and released males to effectively manage their releases. Unfortunately, because most commercially available traps are designed to capture either host-seeking or oviposition-ready females, accurate estimates of male populations are unattainable with existing tools.…”

Pathogenicity and environmental tolerance of commercial and UK native entomopathogenic nematodes (Steinernema and Heterorhabditis spp.) to the larvae of mosquitoes (Aedes aegypti and Ochlerotatus detritus)

“…The Ae. aegypti New Orleans strain has been laboratory reared for many years (Stell et al 2012), and since genetic diversity in longestablished mosquito colonies is typically reduced (Lainhart et al 2015, Azrag et al 2016, it would be thought that lower genetic diversity may increase susceptibility, however, we found the opposite. The reasons for this resistance remain elusive.…”

Circadian oscillation of perireceptor events influence olfactory sensitivity in diurnal and nocturnal mosquitoes

“…gambiae, in which the highest antennal sensitivity was reported at ZT16 (25), overlapping with the highest expression of olfactory proteins. Together these data, we interpret that mosquito's olfactory sensitivity possibly does not follow a fixed temporal trait and is susceptible to change depending on (a) the presence of different chemical odorants and mosquitoes need to detect those to drive various behavioral repertoires ( 60), (b) diverse ecological/environmental habitats (61,62), (c) host-availability and (d) presence of xenobiotics (63,64). Moreover, we hypothesize that under standard insectary conditions, mosquitoes may not need to exhibit foraging flight activity either for nectar or blood, and during the time course, it may minimize their olfactory rhythm, which is obligately required for wild mosquitoes.…”