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At least 55 records · Page 3Linked to original sources
PubMed1999

Electroantennogram and oviposition bioassay responses of Culex quinquefasciatus and Culex tarsalis (Diptera: Culicidae) to chemicals in odors from Bermuda grass infusions.

Odors were collected from the headspace above fermented infusions of Bermuda grass, which commonly are used as attractants in traps for gravid mosquitoes. Coupled gas chromatography-electroantennogram detection (GC-EAD) was used to identify 9 compounds (phenol, p-cresol, 4-ethylphenol, indole, 3-methylindole, nonanal, 2-undecanone, 2-tridecanone, naphthalene) from odor extracts that elicited significant antennal responses from antennae of gravid female Culex quinquefasciatus Say and Culex tarsalis Coquillett mosquitoes. Several of these compounds at appropriate concentrations were weakly attractive to gravid female mosquitoes in laboratory bioassays and/or stimulated more oviposition than water controls. In addition, dimethyltrisulfide, a significant component of odor extract which did not elicit strong responses from female mosquito antennae in GC-EAD assays, also appeared to stimulate oviposition at 1 concentration. A reconstituted blend of the 10 compounds resulted in much stronger and more consistent responses than individual compounds. The blend was attractive to gravid Cx. quinquefasciatus and enhanced oviposition over a range of concentrations spanning 3 orders of magnitude. One concentration of the blend also attracted gravid Cx. tarsalis and enhanced oviposition. However, at the highest concentration tested, the blend was repellent to both species. Overall, these studies demonstrated that gravid mosquitoes are attracted to oviposition sites by blends of compounds rather than by individual chemicals, and that the concentration of compounds in the odor is a critical factor in determining whether responses are positive (attractive, stimulatory) or negative (repellent, deterrent).

Animals↗
PubMed2006

Effect of bacterial quality and density on growth and whole body stoichiometry of Culex quinquefasciatus and Culex tarsalis (Diptera: Culicidae).

Growth characteristics and whole body carbon (C), nitrogen (N), and phosphorus (P) concentrations were examined for the southern house mosquito, Culex quinquefasciatus Say, and Culex tarsalis Coquillett, reared on chemostat-grown bacteria, Pseudomonas aeruginosa. Whole body percentage of C, N, and P of Cx. quinquefasciatus larvae did not differ significantly across three bacterial concentrations (1, 5, and 10 mg of dry mass/liter) and two bacterial quality treatments (culture medium containing 5 microM P versus 50 microM P); whereas the P content of Cx. tarsalis larvae differed between the bacterial quality treatments. Low concentrations of high or low P bacteria decreased mass-specific growth rate (MGR), whereas intermediate and high bacterial concentrations affected MGR asymmetrically, depending on species. High concentrations of P-rich bacteria enhanced the growth rates of Cx. quinquefasciatus larvae relative to growth on the low P diets. Cx. tarsalis larvae reared on low P bacteria grew approximately 3- to 4 times faster than larvae reared on high P bacteria. The observed asymmetric response in MGR may have been because of differential tolerance in larvae to putative toxins present in P. aeruginosa and may provide one reason why Cx. tarsalis larvae are not found in hypereutrophic aquatic habitats.

Animal Feed↗
PubMed1987

Differential effects of Bacillus sphaericus strain 2362 on Culex quinquefasciatus and its competitor Culex cinereus in West Africa.

The larval susceptibility to Bacillus sphaericus strain 2362 of the non-man-biting mosquito Culex cinereus and the urban filariasis vector Culex quinquefasciatus, two competitor mosquitoes in polluted habitats, was compared. In the laboratory, both species ingested a similar amount of B. sphaericus spores when fed c. 2 x 10(5) spores per ml for 30 min. However, in the same experiment, third-instar larvae of Cx quinquefasciatus were reduced by 98% at 24 h exposure while Cx cinereus larvae were only reduced by 6% at 72 h. In the field, preimaginal populations of Cx cinereus ingested, within a week, more than 99% of the applied spores, but showed no significant decrease through 14 days in cesspools treated at 10 g/m2 of a flowable concentrate of B. sphaericus 2362, containing 2 x 10(10) spores/g. It is proposed that specific biological control of Cx quinquefasciatus could result from appropriate treatment of breeding-sites with larvicidal B. sphaericus and competitive displacement by Cx cinereus or other mosquitoes with larvae that are more tolerant of B. sphaericus.

Africa, Western↗
PubMed1990

[Shelters of mosquitoes Culex (Culex) in rural zones (Diptera: Culicidae)].

The human activities carried out in rural zones have been affecting the behavior of mosquitoes of the Culex (Culex) subgenera, which was the reason for undertaking this investigation with a view to registering data on the natural resting places in pastures and on the edge of or within primitive and residual forest areas. Three localities with different mesological conditions, as to type of human activity, all them situated in the Ribeira Valley region of S. Paulo State, Brazil, were chosen. The species most abundantly found were Cx. mollis (28.0%), Cx. declarator (25.0%), Cx. lygrus (13.0%) and Cx. coronator (9.6%). The collection of mosquitoes Cx. bidens + Cx. dolosus + Cx. chidesteri, known to be more urban, was much smaller than that of any other species of the group. With reference to outdoor environments, woodland contributed with 2,281 individuals (71.4%) suggesting their preference for this resting place, except for Cx. quinquefasciatus. Results are evaluated for the determination of the potential domicilation of each species and consequence of the same for the human population.

Animals↗
PubMed2002

Reproductive activity and survival of Culex pipiens pallens and Culex quinquefasciatus (Diptera: Culicidae) in Japan at high temperature.

The egg hatchability, insemination, and longevity of Japanese Culex pipiens pallens Coquillett and Japanese Culex quinquefasciatus Say were compared at 25 and 30 degrees C. Egg hatchability was high in Cx. p. pallens at 25 degrees C, but it was very low at 30 degrees C because almost no females were inseminated at this temperature. In Cx. quinquefasciatus, the egg hatchability and insemination rates were very high, even at 30 degrees C. The longevity of adult females and males was generally shorter in Cx. p. pallens than in Cx. quinquefasciatus at both temperatures. Because high temperatures may restrict the spread of Cx. p. pallens, we suggest that even if this species spreads to Okinawa, the possibility of it becoming established is very low.

Animals↗
PubMed2003

Differences in extent of genetic introgression between sympatric Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in California and South Africa.

Comparisons of five morphological characters, 12 enzyme electrophoresis profiles, and Wolbachia pipientis infection rates were used to characterize populations of members of the Culex pipiens L. complex in California and South Africa. In South Africa, male phallosome DV/D ratio, male maxillary palp index, branching of siphonal seta 1a, the enzyme locus Mdhp-1, and W. pipientis infection rates proved highly diagnostic for separating Culex quinquefasciatus from Cx. pipiens phenotypes. In Johannesburg, where sympatric members of the Cx. pipiens complex were analyzed as one population, a significant Wahlund Effect was observed in the enzyme loci such as Ao, 6-Pgdh, Mdh-2, and Pgm. In California, all populations of the Cx. pipiens complex were in Hardy Weinberg equilibrium at all polymorphic enzyme loci examined. Additionally, in California, all populations had similar W. pipientis infection rates and appeared morphologically identical (except for DV/D ratio, in extreme north and south). These findings indicate that in South Africa, Cx. pipiens and Cx. quinquefasciatus remain as genetically distinct populations and behave as separate species. Conversely, in California, there is considerable genetic introgression between Cx. pipiens and Cx. quinquefasciatus, and they behave as a single species.

Animals↗
PubMed2005

Oviposition preferences of Culex restuans and Culex pipiens (Diptera: Culicidae) for selected infusions in oviposition traps and gravid traps.

Field studies were conducted in southwestern Virginia to determine the ovipositional preferences of Culex restuans and Culex pipiens by using ovitraps and gravid traps baited with selected infusions. For the ovitrap collections, 4 different infusions (manure, hay, grass, and rabbit chow) were used. Significant differences among infusions were detected on most sample dates for both species. For 3 of the first 4 wk of collections, the manure infusion collected significantly more Cx. restuans than all the other infusions. The hay and grass infusions collected the majority of the egg rafts during weeks 5-9. Cx. pipiens egg rafts were absent from the first 3 wk of collections. Of the remaining 6 wk, 4 showed significant differences in attractiveness of infusions, with the hay and grass infusions preferred by Cx. pipiens. Two infusions, manure and hay, were used for the gravid trap experiment and both Cx. restuans and Cx. pipiens data were combined for analysis. Only the first 2 wk showed significance, with manure being preferred over hay in both weeks. In later collections, the relative attractiveness of the hay infusion increased. A seasonal shift in infusion preference may be related to incubation temperature during preparation of the infusions. New infusions were prepared each week and incubation was done outside. Increased attractiveness of the hay infusion coincided with higher average temperatures in July and August. Hay infusion was very effective for trapping both Cx. pipiens and Cx. restuans in southwestern Virginia and is more convenient to use than manure. However, cool outside temperatures in the early season may interfere with the fermentation process and thus incubation should be done for a longer time or brought indoors.

Animals↗
PubMed2005

First record of Culex (Culex) coronator in Louisiana, USA.

The 1st confirmed record of Culex coronator for Louisiana was made at Fort Polk, LA, from carbon dioxide-baited light trap and gravid trap collections performed from April to October 2004. In addition to the new record, 17 mosquito species in 5 genera (Aedes, Anopheles, Coquillettidia, Culex, and Psorophora) were collected. Collection-site and species distribution data are included.

Animals↗
PubMed1986

An interspecific mosquito model for the mesenteronal infection barrier to western equine encephalomyelitis virus (Culex tarsalis and Culex pipiens).

Culex tarsalis, a putative mosquito vector of western equine encephalomyelitis (WEE) virus, is susceptible to peroral infection by WEE virus. The nonvector mosquito, Culex pipiens, has a very high peroral threshold of infection and is considered to be refractory. By parenteral inoculation, both mosquito species are equally susceptible. Thus, Cx. tarsalis and Cx. pipiens represent an excellent model system to examine the mechanisms for the mesenteronal infection barrier to WEE virus. Diethylaminoethyl (DEAE)-dextran (1.6 mg/ml), when added to a pledget bloodmeal that contained high concentrations of WEE virus, enhanced peroral infection rates of Cx. pipiens. In Cx. tarsalis, a reduction in infection rates was observed when low WEE concentrations of virus were ingested. DEAE-dextran had no apparent effects on the dissemination of WEE after infection of either mosquito species. It is suggested that the peroral enhancement of WEE viral infection observed with Cx. pipiens may be related to random, nonspecific mechanisms of infection, since it requires high titers of ingested WEE virus. Interference with specific binding of WEE virus to cellular receptor sites is suggested to explain the reduction in WEE viral infection rates in Cx. tarsalis. Altering the pH of the ingested infectious bloodmeal did not affect the WEE viral infection rate of Cx. pipiens, within the range of 6.0-8.5. Cx. tarsalis was optimally infected when the infectious bloodmeal was pH 8.0, and the infection rate was significantly reduced when the infectious blood was at either extreme of the pH range tested. This is again interpreted to indicate that different mechanisms control the peroral infection of Cx. tarsalis and Cx. pipiens with WEE virus. The mesenteronal infection barrier to WEE virus in Cx. pipiens is associated with an inability of the virus to adsorb and/or penetrate mesenteronal epithelial when administered perorally. The barrier is not related to an inability of the Cx. pipiens mesenteronal epithelial cells to support viral multiplication since these cells become infected when the virus is administered parenterally.

Animals↗
PubMed1999

Effects of high temperature on the emergence and survival of adult Culex pipiens molestus and Culex quinquefasciatus in Japan.

The emergence rate and adult survival (longevity) of Japanese strains of Culex pipiens molestus and Culex quinquefasciatus were compared at temperatures of 21, 25, and 30 degrees C. The pupation and emergence rates in both strains were higher at 21 and 25 degrees C than at 30 degrees C. The adult emergence rate, especially in females, was lower in Cx. p. molestus than in Cx. quinquefasciatus. Longevity of females and males was lower in Cx. p. molestus at 25 degrees C and above. The survival of Cx. p. molestus was adversely affected by temperatures of 28 degrees C and higher. High temperature may restrict the distribution of this species. Therefore, if Cx. p. molestus infests the Okinawa region, the likelihood that it will become established is minimal.

Animals↗
PubMed1999

Effects of neem products containing azadirachtin on blood feeding, fecundity, and survivorship of Culex tarsalis and Culex quinquefasciatus (Diptera: Culicidae).

When late 3rd or early 4th-instar larvae of Culex tarsalis Coquillett and Culex quinquefasciatus Say mosquitoes were treated with sublethal dosages of neem insecticide until pupation, the blood-feeding activity of the resulting adults was essentially the same as that of untreated controls. In contrast, blood-feeding activity was suppressed when newly emerged adults were fed continuously on 10 parts per million (ppm) or 50 ppm azadirachtin (AZ) in 10% sucrose solution for seven days. Fecundity was also reduced by the various neem treatments. When late 3rd or early 4th-instar larvae were treated with 0.010 ppm AZ to pupation, the resultant females had a lower rate of oviposition than did the untreated controls after a full blood meal. When late instar larvae were treated at 0.005 ppm and 0.010 ppm AZ, the resultant females produced smaller egg rafts after a full blood meal, as compared to the controls, but egg viability was not affected. In newly emerged adults feeding continuously on 10 ppm and 50 ppm AZ in 10% sucrose for seven days (before blood feeding), the oviposition rate, size of egg raft, and hatching rate of the eggs after a full blood meal were all reduced. When newly blood-fed adults were fed continuously on 10 ppm and 50 ppm AZ in 10% sucrose for five days, their oviposition rate was lower than controls in most cases, but the egg raft size and viability of eggs were not affected. In freshly blood-fed females topically treated with AZ with 1 or 5 micrograms/female, the oviposition rate and size of egg rafts were generally reduced. The females receiving topical treatment laid eggs and their hatching was not affected. The longevity of adult females feeding continuously on 10 ppm and 50 ppm AZ in 10% sucrose solution after emergence was reduced, whereas, the longevity of males was only affected at the higher concentration.

Animals↗
PubMed2004

Rapid assays for identification of members of the Culex (Culex) pipiens complex, their hybrids, and other sibling species (Diptera: culicidae).

Mosquitoes in the Culex (Culex) pipiens complex of species, known as vectors of periodic filariasis and deadly encephalitides, have recently emerged as important vectors of West Nile virus in the United States. Highly conserved morphology but marked differences in potential vectorial capacity require the development of polymerase chain reaction (PCR)-based tests that unambiguously distinguish among the different species. We introduce and describe a series of PCR-based assays that use polymorphisms in the second intron of the acetylcholinesterase-2 (ace-2) locus for the identification of members of the Cx. pipiens complex (Cx. pipiens, Cx. quinquefasciatus, Cx. p. pallens, Cx. australicus), two other species that are commonly mislabeled as Cx. pipiens (Cx. torrentium and Cx. pervigilans), as well as hybrids between Cx. pipiens and Cx. quinquefasciatus.

Acetylcholinesterase↗
PubMedDate not supplied

[Differentiation between the urban mosquito Culex pipiens pipiens F. molestus and Culex torrentium (Diptera: Culicidae) by the molecular genetic methods].

The molecular characters suitable for the differentiation between the autogenous form of Culex pipiens pipiens (the urban mosquito) and the species Culex torrentium, which was previously identified erroneously as an anautogenous form of C. pipiens pipiens (Shaikevich, Vinogradova, 2004), are given. These mosquitoes differ in the infection by the endosymbiotic bacteria Wolbachia pipientis, 6 transitions among 247 nucleotide sequences of 3' part of the cytochrome oxidase subunit I (COI) gene of mitochondrial DNA (mtDNA), in the mtDNA fragments resulted from the restriction analysis, and in the lengths of second internal transcribed spacer (ITS2) sequences in the ribosomal DNA.

Animals↗
PubMed2006

Laboratory studies on the possibility of Culex (Culex) pipiens l. to harbour and transmit Hepatozoon matruhensis to the Egyptian snake Psammophis schokari.

A successful experimental infection of Psammophis schokari snake with Hepatozoon matruhensis through Culex (Culex) pipiens bites was carried out under laboratory condition of 20 +/- 1 degrees C and 60-70 % R.H. The period monitored for gametocyte maturation ranged from 38 to 42 days while the recorded prepatent period ranged from 28 to 35 days. The effect of infection was nonsignificant on longevity, incubation period and percenttage of egg hatching (P>0.05). Meanwhile a significant increase (P<0.05) in the preoviposition period together with a significant reduction (P<0.001) in the number of eggs deposited of infected females were recorded.

Animals↗
PubMed2006

Experimental infection of Culex annulirostris, Culex gelidus, and Aedes vigilax with a yellow fever/Japanese encephalitis virus vaccine chimera (ChimeriVax-JE).

Australian mosquitoes from which Japanese encephalitis virus (JEV) has been recovered (Culex annulirostris, Culex gelidus, and Aedes vigilax) were assessed for their ability to be infected with the ChimeriVax-JE vaccine, with yellow fever vaccine virus 17D (YF 17D) from which the backbone of ChimeriVax-JE vaccine is derived and with JEV-Nakayama. None of the mosquitoes became infected after being fed orally with 6.1 log(10) plaque-forming units (PFU)/mL of ChimeriVax-JE vaccine, which is greater than the peak viremia in vaccinees (mean peak viremia = 4.8 PFU/mL, range = 0-30 PFU/mL of 0.9 days mean duration, range = 0-11 days). Some members of all three species of mosquito became infected when fed on JEV-Nakayama, but only Ae. vigilax was infected when fed on YF 17D. The results suggest that none of these three species of mosquito are likely to set up secondary cycles of transmission of ChimeriVax-JE in Australia after feeding on a viremic vaccinee.

Aedes↗