Staggered larval time-to-hatch and insecticide resistance in the major malaria vector Anopheles gambiae S form

Kaiser, Maria; Koekemoer, Lizette L.; Coetzee, Maureen; Hunt, Richard H.; Brooke, Basil D.

doi:10.1186/1475-2875-9-360

Cited by 12 publications

(21 citation statements)

References 19 publications

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“…To counter the tendency for A. gambiae egg cohorts to hatch asynchronously over several days or even weeks (Yaro et al, 2006;Kaiser et al, 2010), synchronous hatching was forced. To achieve this, eggs laid overnight by groups of females were introduced into rearing trays of deionized water lined with filter paper strips; trays were maintained in the insectary for 48h.…”

Section: Acute Salinity Assaysmentioning

confidence: 99%

Dose and developmental responses of Anopheles merus larvae to salinity

White

Kundert

Turissini

et al. 2013

Journal of Experimental Biology

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SUMMARY Saltwater tolerance is a trait that carries both ecological and epidemiological significance for Anopheles mosquitoes that transmit human malaria, as it plays a key role in determining their habitat use and ecological distribution, and thus their local contribution to malaria transmission. Here, we lay the groundwork for genetic dissection of this trait by quantifying saltwater tolerance in three closely related cryptic species and malaria vectors from the Afrotropical Anopheles gambiae complex that are known to differ starkly in their tolerance to salinity: the obligate freshwater species A. gambiae and A. coluzzii, and the saltwater-tolerant species A. merus. We performed detailed comparisons of survivorship under varying salinities, using multiple strains of A. gambiae, A. coluzzii and A. merus, as well as F1 progeny from reciprocal crosses of A. merus and A. coluzzii. Additionally, using immunohistochemistry, we compared the location of three ion regulatory proteins (Na+/K+-ATPase, carbonic anhydrase and Na+/H+-antiporter) in the recta of A. coluzzii and A. merus reared in freshwater or saline water. As expected, we found that A. merus survives exposure to high salinities better than A. gambiae and A. coluzzii. Further, we found that exposure to a salinity level of 15.85 g NaCl l−1 is a discriminating dose that kills all A. gambiae, A. coluzzii and A. coluzzii–A. merus F1 larvae, but does not negatively impact the survival of A. merus. Importantly, phenotypic expression of saltwater tolerance by A. merus is highly dependent upon the developmental time of exposure, and based on immunohistochemistry, salt tolerance appears to involve a major shift in Na+/K+-ATPase localization in the rectum, as observed previously for the distantly related saline-tolerant species A. albimanus.

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Section: Acute Salinity Assaysmentioning

confidence: 99%

Dose and developmental responses of Anopheles merus larvae to salinity

White

Kundert

Turissini

et al. 2013

Journal of Experimental Biology

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“…gambiae , from western Kenya, is described here, but we found similar characteristics of egg dormancy and agitation-induced hatching in the Suakoko strain from Liberia (unpublished data). Furthermore, Kaiser et al (2010) described a similar phenomenon in the GAH strain from Ghana, although with a higher rate of spontaneous hatching. All three examples are S-form An.…”

Section: Discussionmentioning

confidence: 66%

“…The last method of collecting anopheline eggs is common in laboratories. This interpretation is supported by the genetic analysis of delayed (“late”) hatching by Kaiser et al (2010), who noticed that the frequency of “early” hatching was increased by egg disturbance.…”

Section: Discussionmentioning

confidence: 82%

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Delayed Egg Hatching ofAnopheles gambiae(Diptera: Culicidae) Pending Water Agitation

2014

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Mosquito eggs laid on water surfaces typically hatch spontaneously soon after the embryos within them become fully formed first-instar larvae. However, we have found that Anopheles gambiae Giles, an important vector of malaria in Africa, exhibits delayed hatching until the water surface is agitated, a feature overlooked in most laboratory colonies. Agitation within 24 h postoviposition, before embryonation was complete, failed to stimulate delayed postembryonic hatching of isolated eggs on the following day (day 2), when <1% had hatched spontaneously. However, 5 min of water agitation of these dormant pharate first-instar larvae on day 2 resulted in an almost immediate hatch of 63.3 versus 0% of nonagitated controls, plus another 3.9 versus 0.3%, respectively, during the following 24 h. With daily agitation, installment hatching occurred mainly during 2– 6 d postoviposition. The mean cumulative hatch after 7 d of daily agitation was 83.1 versus 1.1% of nonagitated eggs. Experiments with eggs in groups demonstrated that egg density and activity of already-hatched larvae had no stimulatory effect. Eggs stored 1–4 wk at 25.5 or at 15.5°C, and then agitated daily for 6 d at 25.5°C, showed a gradual decline in viability. Viability was sustained longer at the lower temperature. Implications of agitation-induced egg hatching for rainy-season and dry-season ecology of An. gambiae are discussed. Suspended hatching and cool storage already are proving convenient for efficient mass rearing and accurate modeling of weather-based population dynamics.

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“…There is ample evidence that at least some of these genes have the potential to threaten the effectiveness of current malaria vector control interventions (16). Figure 1 clearly shows the evidence of accumulation of malaria vector resistance to commonly used insecticides in several malaria endemic countries worldwide, including Côte d'Ivoire (17), South Africa (18), Burkina Faso (19), Ghana (20), Equatorial Guinea (21), Angola (22), Gabon (23), Benin (24), Ethiopia (25) and Congo-Brazzaville (26).…”

Section: Vector Control: a Friend In Need To Save Livesmentioning

confidence: 99%

Insecticide Resistance in Insect Vectors of Disease with Special Reference to Mosquitoes: A Potential Threat to Global Public Health

Karunamoorthi

Sabesan

2013

Health Scope

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Context: Arthropod-borne diseases are remaining as a major public health issue in the resource-constrained settings. Mosquitoes are closely associated with mankind since time immemorial and play an important role in the transmission of many dreadful diseases like malaria, filariasis, Japanese encephalitis, dengue and yellow fever. Over the decades, vector control is an important element to minimize the vector-borne disease burden worldwide and in fact, it heavily relies upon synthetic insecticides as a mainstay. However the overuse and misuse of insecticides have led to the emergence of resistance, which undermines the potentiality of vector control. Evidence Acquisition: In order to pursue effective research pertained to this issue, a detailed search on Scopus, Medline, Google Scholar and academic premier databases has been conducted between the time periods of 1955 and 2012. Results: Over the past six decades, insecticides are serving as one of the important arsenals in the fight against vector-borne diseases to save hundreds of millions of lives. Consequently, in the last decade we have attained a remarkable success to combat with many diseases particularly malaria due to the combined effect of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). Currently, malaria mortality rates have drastically fallen by more than 25% globally, 33% in sub-Saharan Africa and over a million lives have been saved attributable to massive scale-up of LLINs and IRS. Since, both LLINs and IRS are cost-effective and robust form of interventions; they are serving as a central pillar in the National Malaria Control Programmes (NMCPs) of malaria endemic countries. Nevertheless, LLINs are easy-to-deliver, most economical and practical even in the resource-poor settings, where implementation of IRS is not feasible. The heavy reliance, recurrent and inappropriate insecticide applications are key sources for resistance which is a potential threat to the global public health. Therefore, it has to be addressed immediately to sustain the recent success of vector control, unless otherwise it would become uncertain. Conclusions: Though, development of resistance is an evolutionary phenomenon, it can be tackled judiciously by implementing appropriate and comprehensive resistance monitoring and management strategies within the framework of integrated vector management. This scrutiny recommends the following measures; (i) identification of effective novel tools for monitoring and evaluation, (ii) searching for alternative interventions to minimize the further resistance evolution as well as to preserve the efficiency of existing insecticides, (iii) exploration of next generation vector control tools in terms of nets and new classes of non-pyrethroid insecticide formulation with new mode of action, (iv) building partnership by bringing together the people actively engaged in the vector control, like public health experts, policy-makers, researchers, medical entomologists and insecticide manufacturers, could ideally pave the ...

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Staggered larval time-to-hatch and insecticide resistance in the major malaria vector Anopheles gambiae S form

Cited by 12 publications

References 19 publications

Dose and developmental responses of Anopheles merus larvae to salinity

Dose and developmental responses of Anopheles merus larvae to salinity

Delayed Egg Hatching ofAnopheles gambiae(Diptera: Culicidae) Pending Water Agitation

Insecticide Resistance in Insect Vectors of Disease with Special Reference to Mosquitoes: A Potential Threat to Global Public Health

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