AUTOGENY AND BLOOD-FEEDING BY CULEX TARSALIS (DIPTERA: CULICIDAE) AND THE INTERVAL BETWEEN OVIPOSITION AND FEEDING

1982 ◽  
Vol 114 (6) ◽  
pp. 515-521 ◽  
Author(s):  
R. L. Nelson ◽  
M. M. Milby

AbstractFemale Culex tarsalis Coquillett trapped in CO2-baited light traps or reared from field-collected pupae were marked with fluorescent dust, released, and recaptured in traps baited with CO2 with or without light. Recaptures of trapped females peaked on the first night of recapture collections. Recaptures of reared females peaked on the first or second night when autogeny rates were low (25–44%) but 2-4 nights later when rates were high (86–88%). It was concluded that autogenous females did not seek blood until after they had oviposited, and that autogenously induced delays in feeding probably influence the extent of virus transmission by C. tarsalis.Stretched follicular tubes indicating recent oviposition were found in 23.4% and 5.2% of empty parous females from shelters and CO2-baited traps, respectively, and in 2.3% of freshly engorged parous females from shelters. Females often failed to blood-feed until at least the second night after oviposition.

Author(s):  
Bruno Leite Rodrigues ◽  
Glaucilene da Silva Costa ◽  
Paloma Helena Fernandes Shimabukuro

Abstract The transmission of pathogens that cause leishmaniases occurs by the bite of female sand flies (Diptera: Psychodidae) in their vertebrate hosts, which makes the identification of their bloodmeal sources an important step for the control and epidemiology of these diseases. In Brazil, the state of Roraima has a great diversity of sand flies, vertebrate hosts, and protozoan Leishmania, but little is known about the host blood-feeding preferences of sand flies. Thus, we evaluated the bloodmeal sources of sand flies collected from their sylvatic habitats in Parque Nacional do Viruá, Roraima. Fieldwork was carried-out between 13th and 18th August 2019 using CDC light traps. Sand flies were slide-mounted and morphologically identified using the head and last segments of the abdomen. Engorged females had their DNA extracted, followed by amplification and sequencing of the cytochrome b (cytb) molecular marker for vertebrates. Sequences were analyzed and compared with those from GenBank using the BLASTn search tool, in addition to the reconstruction of a phylogenetic tree to demonstrate the clustering pattern of these sequences. A total of 1,209 sand flies were identified, comprising 20 species, in which the most abundant were Psychodopygus ayrozai (Barretto and Coutinho) (42.10%) and Psychodopygus chagasi (Costa Lima) (26.22%). Bloodmeal source identification was successfully performed for 34 sand flies, that confirm four vertebrate species, being the most abundant the armadillo Dasypus novemcinctus Linnaeus, 1758 (Cingulata: Dasypodidae).


2020 ◽  
Vol 20 (6) ◽  
Author(s):  
Fallon Fowler ◽  
Tashiana Wilcox ◽  
Stephanie Orr ◽  
Wes Watson

Abstract Understanding collection methodologies and their limitations are essential when targeting specific arthropods for use in habitat restoration, conservation, laboratory colony formation, or when holistically representing local populations using ecological surveys. For dung beetles, the most popular collection methodology is baited traps, followed by light traps and unbaited flight-intercept traps during diversity surveys. A less common collection method, flotation, is assumed to be laborious and messy, and so only a handful of papers exist on its refinement and strengths. Our purpose was threefold: First, we tested the recovery and survival rates of Labarrus (=Aphodius) pseudolividus (Balthasar) and Onthophagus taurus (Schreber) when floating beetle-seeded dung pats to determine potential collection and safety issues. We collected 72.4 and 78% of the seeded L. pseudolividus and O. taurus, respectively, with >95% survival rating. Second, we developed a flotation-sieving technique that enables users to rapidly collect and passively sort dung beetles with less time and effort. Specifically, we often collected 50–100 g of wild dung beetles within a couple of hours of gathering dung and sorted them in a couple more by allowing dung beetles to sort themselves by size within a series of sieves; Third, we reviewed flotation-based advantages and disadvantages in comparison to other methodologies.


Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1441
Author(s):  
Alexander Bergman ◽  
Emma Dahl ◽  
Åke Lundkvist ◽  
Jenny C. Hesson

A crucial, but unresolved question concerning mosquito-borne virus transmission is how these viruses can remain endemic in regions where the transmission is halted for long periods of time, due to mosquito inactivity in, e.g., winter. In northern Europe, Sindbis virus (SINV) (genus alphavirus, Togaviridae) is transmitted among birds by Culex mosquitoes during the summer, with occasional symptomatic infections occurring in humans. In winter 2018–19, we sampled hibernating Culex spp females in a SINV endemic region in Sweden and assessed them individually for SINV infection status, blood-feeding status, and species. The results showed that 35 out of the 767 collected mosquitoes were infected by SINV, i.e., an infection rate of 4.6%. The vast majority of the collected mosquitoes had not previously blood-fed (98.4%) and were of the species Cx. pipiens (99.5%). This is the first study of SINV overwintering, and it concludes that SINV can be commonly found in the hibernating Cx. pipiens population in an endemic region in Sweden, and that these mosquitoes become infected through other means besides blood-feeding. Further studies on mosquito ecology and viral interactions are needed to elucidate the mechanisms of the persistence of these viruses over winter.


1982 ◽  
Vol 114 (1) ◽  
pp. 85-86 ◽  
Author(s):  
P. W. Arntfield ◽  
W. J. Gallaway ◽  
R. A. Brust

Diapause development in Culex tarsalis Coquillett has been characterized by reduced blood-feeding to complete termination of ovariole development at or before stage IIa (Bennington et al. 1958; Schaefer and Washino 1970; Schaefer et al. 1971; Bellamy and Corbet 1973; Mitchell 1979). The role that diapausing Culex species have in overwintering arboviruses has been examined (Eldridge 1966, 1968; Eldridge et al. 1972; Reeves 1974; Eldridge and Bailey 1979; Mitchell 1979). Gonotrophic dissociation and its implications for survival of the vector and virus has been reviewed by Washino (1977). Eldridge (1966) indicated gonotrophic dissociation was possible in Culex pipiens L. incubated at low temperature and short daylength and later reported failure of ovarioles of prehibernating C. pipiens to mature following a blood meal (Eldridge and Bailey 1979). Eldridge et al. (1972) reported that Culex restuans Theobald exhibited gonotrophic dissociation in response to conditioning by short daylength and low temperature. Mitchell (1981) has reported blood-feeding and gonotrophic dissociation in a significant portion of diapausing Culex tarsalis from Colorado, when females were kept at 15°C and at short daylength conditions.


Viruses ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 215 ◽  
Author(s):  
Anna C. Fagre ◽  
Rebekah C. Kading

Bats are known to harbor and transmit many emerging and re-emerging viruses, many of which are extremely pathogenic in humans but do not cause overt pathology in their bat reservoir hosts: henipaviruses (Nipah and Hendra), filoviruses (Ebola and Marburg), and coronaviruses (SARS-CoV and MERS-CoV). Direct transmission cycles are often implicated in these outbreaks, with virus shed in bat feces, urine, and saliva. An additional mode of virus transmission between bats and humans requiring further exploration is the spread of disease via arthropod vectors. Despite the shared ecological niches that bats fill with many hematophagous arthropods (e.g. mosquitoes, ticks, biting midges, etc.) known to play a role in the transmission of medically important arboviruses, knowledge surrounding the potential for bats to act as reservoirs for arboviruses is limited. To this end, a comprehensive literature review was undertaken examining the current understanding and potential for bats to act as reservoirs for viruses transmitted by blood-feeding arthropods. Serosurveillance and viral isolation from either free-ranging or captive bats are described in relation to four arboviral groups (Bunyavirales, Flaviviridae, Reoviridae, Togaviridae). Further, ecological associations between bats and hematophagous viral vectors are characterized (e.g. bat bloodmeals in mosquitoes, ingestion of mosquitoes by bats, etc). Lastly, knowledge gaps related to hematophagous ectoparasites (bat bugs and bed bugs (Cimicidae) and bat flies (Nycteribiidae and Streblidae)), in addition to future directions for characterization of bat-vector-virus relationships are described.


1975 ◽  
Vol 65 (1) ◽  
pp. 81-96 ◽  
Author(s):  
John B. Davies

AbstractThe biting activity of Culex (Melanoconion) portesi Senevet & Abonnenc and C. (M.) taeniopus D. & K. in a secondary seasonal marsh forest in Trinidad was studied by means of catches by six mouse-baited suction traps, and a single light-trap. The traps were cleared at hourly intervals between 17.00 h and 07.00 h on nights which approximated to the new, first quarter, full and last quarter phases of the moon. The catches were compared with illumination at canopy and ground level which was estimated by selenium photocells whose output was recorded on the continuous chart of a servo-potentiometer. Humidity, rainfall, temperature and cloud cover were also recorded. In the suction traps both species showed peaks of activity at evening and dawn twilight at new moon, although the dawn peak was not very pronounced with C. taeniopus, but this pattern was modified on other nights in a manner which was consistent with moon age. At full moon the evening and dawn peaks were replaced by increased activity during moonrise and the middle of the night. The light-traps failed to show the evening and dawn activity and did not always duplicate the baited traps during darkness. Two hypotheses based on either a permissive range of illumination or an underlying circadian rhythm are discussed; neither fully explains the observed biting activity. Although an association between moonlight and biting activity does exist, an understanding of its nature will require more experimental data.


1977 ◽  
Vol 67 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Alan R. Walker

AbstractLight-traps were used to sample populations of C. comutus De Meillon, C. pallidipennis G, I. & M. and C. schultzei (End.) gp. at sites at Embakasi, Kiboko and Makindu between 1971 and 1975. The samples were graded into age-groups by the degree of abdominal pigmentation, estimates of calendar ageing were made, and the seasonal variation in age-structure of the populations was recorded. Survival rates were calculated on the basis of a graphical model of the continually overlapping generations, and the survival rate of 0·8 was found typical. This rate is considered sufficiently high for C. cornutus, C. pallidipennis and C. schultzei gp. to act as vectors of bluetongue virus disease of sheep and/or ephemeral fever virus disease of cattle.


2012 ◽  
Vol 144 (5) ◽  
pp. 667-671 ◽  
Author(s):  
Curtis Russell ◽  
Fiona F. Hunter

AbstractWe tested whether the known bird-biting mosquito, Culex pipiens Linnaeus (Diptera: Culicidae), is attracted to human hosts by placing humans at ground level (∼1.5 m) or in the forest canopy (∼5 m) in a Niagara woodlot. Modified Centers for Disease Control (CDC) miniature light traps (no light, no CO2) were placed next to the human hosts to capture the attracted mosquitoes. The human-baited traps were compared with control traps (standard CDC miniature light traps with CO2, but no light). As expected from previous research, there were more C. pipiens captured at the higher elevation than at ground level. Generally, they were attracted to control traps more than to human-baited traps at 5 m, whereas at 1.5 m there was no difference between the two trap types. As a comparison, most Aedes vexans (Meigen) mosquitoes were captured at the 1.5 m elevation but there were significantly more captured in the control traps than the human-baited traps during all periods. Because C. pipiens is attracted to humans throughout the entire season at the 1.5 m height (where they might encounter humans), it is likely that C. pipiens can serve as a bridge vector of West Nile virus (WNV).


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