The Winter Biology of Culex tarsalis (Diptera: Culicidae) in Kern County, California1

Bellamy, R. E.; Reeves, William C.

doi:10.1093/aesa/56.3.314

Cited by 36 publications

(25 citation statements)

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“…Some North American arboviruses are vertically transmitted (Watts et al 1973, Turell et al 1982, Tesh 1984, Turell 1988, Goddard et al 2003, Phillips and Christensen 2006, and overwintering of infected eggs may provide a mechanism for virus persistence at a given locale from year to year. Less common, however, is overwintering of arboviruses in adult insects (Reeves et al 1958, Bellamy and Reeves 1963, Reeves 1974, Reisen et al 1986, 2006a, Rosen 1987, Reisen 1990. Only a few virus isolations from adult mosquitoes in the winter have been reported in central and northern North America (Blackmore and Winn 1956, Bailey et al 1978, Nasci et al 2001, Farajollahi et al 2005, and it is unclear whether overwintering in adult vectors is an important component of the transmission cycles for most of the well-studied arboviruses (Mitchell 1988).…”

Section: Introductionmentioning

confidence: 99%

Winter Ecology of Buggy Creek Virus (Togaviridae,Alphavirus) in the Central Great Plains

Brown

Strickler²,

Moore³

et al. 2010

Vector-Borne and Zoonotic Diseases

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A largely unanswered question in the study of arboviruses is the extent to which virus can overwinter in adult vectors during the cold winter months and resume the transmission cycle in summer. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an unusual arbovirus that is vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) and amplified by the ectoparasitic bug's main avian hosts, the migratory cliff swallow (Petrochelidon pyrrhonota) and resident house sparrow (Passer domesticus). Bugs are sedentary and overwinter in the swallows' mud nests. We evaluated the prevalence of BCRV and extent of infection in swallow bugs collected at different times in winter (October-early April) in Nebraska and explored other ecological aspects of this virus's overwintering. BCRV was detected in 17% of bug pools sampled in winter. Virus prevalence in bugs in winter at a site was significantly correlated with virus prevalence at that site the previous summer, but winter prevalence did not predict BCRV prevalence there the following summer. Prevalence was higher in bugs taken from house sparrow nests in winter and (in April) at colony sites where sparrows had been present all winter. Virus detected by reverse transcription (RT)-polymerase chain reaction in winter was less cytopathic than in summer, but viral RNA concentrations of samples in winter were not significantly different from those in summer. Both of the BCRV lineages (A, B) overwintered successfully, with lineage A more common at sites with house sparrows and (in contrast to summer) generally more prevalent in winter than lineage B. BCRV's ability to overwinter in its adult vector probably reflects its adaptation to the sedentary, long-lived bug and the ecology of the cliff swallow and swallow bug host-parasite system. Its overwintering mechanisms may provide insight into those of other alphaviruses of public health significance for which such mechanisms are poorly known.

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Section: Introductionmentioning

confidence: 99%

Winter Ecology of Buggy Creek Virus (Togaviridae,Alphavirus) in the Central Great Plains

Brown

Strickler²,

Moore³

et al. 2010

Vector-Borne and Zoonotic Diseases

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“…At northern latitudes, female Culex are induced to enter reproductive diapause after larvae are ex-posed to shortening day lengths and cooling water temperatures (Eldridge 1987). Emerging females that are programmed for diapause do not take bloodmeals (Bellamy andReeves 1963, Mitchell 1981), so the most likely means by which a diapausing, nulliparous female may become infected with WNV is through vertical transmission.…”

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confidence: 99%

Experimental and Natural Vertical Transmission of West Nile Virus by California <I>Culex</I> (Diptera: Culicidae) Mosquitoes

et al. 2013

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Culex (Diptera: Culicidae) mosquitoes, the primary summer vectors of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), also may serve as overwintering reservoir hosts. Detection of WN viral RNA from larvae hatched from eggs deposited by infected females during late summer and fall may provide evidence for the vertical passage of WNV to overwintering cohorts. To determine whether vertical transmission to the overwintering generation occurs in populations of Culex mosquitoes throughout California, larvae from naturally infected females were tested by family for WN viral RNA by real-time quantitative reverse transcription-polymerase chain reaction during August through October 2011. Viral RNA was detected in 34 of 934 Culex tarsalis Coquillett and Cx. pipiens complex females that laid viable egg rafts. From these egg rafts, Þrst-instar larvae from nine families tested positive, yielding an overall Þeld vertical transmission rate of 26% (n ϭ 34). To determine whether the WNV may be lost transtadially during development to the adult stage, Þrst-instar larvae and adult progeny from experimentally infected Cx. pipiens complex females were assessed for the presence and quantity of WN viral RNA. Most (Ϸ75%) WNV infections were lost from positive families during larval development to the adult stage. In Þeld and laboratory studies, only infected mothers with mean cycle threshold scores Յ20 vertically transmitted WNV to larval progeny, adult progeny, or both. In summary, vertical transmission of WNV was detected repeatedly in naturally infected Culex mosquitoes collected throughout California during late summer and fall, with females having high titered infections capable of passing WNV onto their progeny destined for overwintering.

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“…pipiens [Eldridge 1968]) exposed to cool temperature and short day length gave rise to females with primary follicles arrested at stage I and with 1°/2° follicular ratios <1.5 (Reisen 1986). In California these females do not blood feed but remain vagile and metabolically active, repopulating resting sites after removal sampling (Bellamy and Reeves 1963) and imbibing fructose (Reisen et al 1986c). These females at overwintering stage I (Reisen et al 1986a) apparently remain in diapause until after the winter solstice (Reisen et al 1995b), after which termination seems governed by temperature (Bennington et al 1958, Bennington andSherman 1960).…”

Section: Discussionmentioning

confidence: 99%

“…Warm winters were positively correlated with subsequent increases in vernal mosquito abundance (Reisen et al 2008a) and perhaps summer West Nile virus (Flaviviridae, Flavivirus, WNV) activity (Reisen et al 2006b). Historical in-depth studies of winter Culex tarsalis Coquillett populations collected resting from privies and bridges in Kern County, CA, found that although blood feeding terminated in December, blood engorged females could be collected again as soon as mid-January (Bellamy and Reeves 1963) and that these females fed mostly on passerine birds (Tempelis et al 1965). During autumn, female populations bifurcated into gonotrophically inactive nullipars that entered diapause and gonotrophically active pars that died-out by December; parity remained low through January and then increased again in February, which coincided with an increase in the numbers of females collected host-seeking at dry ice-baited traps (Nelson 1964 and measurements of the primary and secondary follicles, Cx.…”

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confidence: 99%

Effects of Warm Winter Temperature on the Abundance and Gonotrophic Activity ofCulex(Diptera: Culicidae) in California

Reisen¹,

Thiemann

Barker

et al. 2010

J Med Entomol

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Culex tarsalis Coquillett, Cx. quinquefasciatus Say, and Cx. pipiens L. were collected during the warm winter of 2009 using dry ice-baited and gravid traps and walk-in red boxes positioned in desert, urban, and agricultural habitats in Riverside, Los Angeles, Kern, and Yolo Counties. Temperatures exceeded the preceding 50 yr averages in all locations for most of January, whereas rainfall was absent or below average. Abundance of Culex species in traps during January ranged from 83 to 671% of the prior 5 yr average in all locations. Few females collected resting were in diapause during January based on follicular measurements. Evidence for early season gonotrophic activity included the detection of freshly bloodfed, gravid, and parous females in resting collections, gravid oviposition site-seeking females in gravid female traps, and nulliparous and parous host-seeking females at dry ice-baited traps. Female Culex seemed to employ multiple overwintering strategies in California, including larval and adult quiescence, adult female diapause, and an intermediate situation with adult females collected with enlarged follicles, but without evident vitellogenesis. West Nile, St. Louis, or western equine encephalitis viruses were not detected in 198 pools of adults or 56 pools of adults reared from field-collected immatures collected during January and February 2009. Our preliminary data may provide insight into how climate change may extend the mosquito season in California. KeywordsCulex; diapause; overwintering; California In California, the initiation of gonotrophic activity by Culex mosquitoes during winter or early spring establishes subsequent phenology and determines the earliest date for potential mosquito-borne encephalitis virus transmission, regardless of the viral overwintering mechanism(s) (Reisen et al. 2006a). Warm winters were positively correlated with subsequent increases in vernal mosquito abundance (Reisen et al. 2008a) and perhaps summer West Nile virus (Flaviviridae, Flavivirus, WNV) activity (Reisen et al. 2006b). Historical in-depth studies of winter Culex tarsalis Coquillett populations collected resting from privies and bridges in Kern County, CA, found that although blood feeding terminated in December, blood engorged females could be collected again as soon as mid-January (Bellamy and Reeves 1963) and that these females fed mostly on passerine birds (Tempelis et al. 1965). During autumn, female populations bifurcated into gonotrophically inactive nullipars that entered diapause and gonotrophically active pars that died-out by December; parity remained low through January and then increased again in February, which coincided with an increase in the numbers of females collected host-seeking at dry ice-baited traps (Nelson 1964 and measurements of the primary and secondary follicles, Cx. tarsalis females emerging after the autumnal equinox appeared to enter reproductive diapause (Reisen et al. 1986b(Reisen et al. , 1995b in response to the fourth-instar larvae being exposed to short photo...

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The Winter Biology of Culex tarsalis (Diptera: Culicidae) in Kern County, California1

Cited by 36 publications

References 0 publications

Winter Ecology of Buggy Creek Virus (Togaviridae,Alphavirus) in the Central Great Plains

Winter Ecology of Buggy Creek Virus (Togaviridae,Alphavirus) in the Central Great Plains

Experimental and Natural Vertical Transmission of West Nile Virus by California <I>Culex</I> (Diptera: Culicidae) Mosquitoes

Effects of Warm Winter Temperature on the Abundance and Gonotrophic Activity ofCulex(Diptera: Culicidae) in California

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