Search results for "Culex"
showing 10 items of 34 documents
Transmission studies of a European Sindbis virus in the floodwater mosquito Aedes vexans (Diptera: Culicidae)
2002
Abstract Sindbis viruses are arthropod-borne viruses, which are maintained in nature in a Culex mosquitobird associated transmission cycle, but Aedes species have been suspected as playing a role in infecting humans. In this study, we addressed the question whether or not Germany's most abundant floodwater mosquito species Aedes vexans (Diptera, Culicidae) can serve as an efficient vector for Sindbis viruses. Firstly, the overall susceptibility of Ae. vexans was tested by intrathoracic inoculation of 40 plaque forming units (PFU) Karelian fever virus (KFV, an European Sindbis virus isolate) per female mosquito. Viral titres rose after inoculation reaching a maximum (about a 350-fold increas…
A Red Eye Colour Mutation in Culex pipiens after X-irradiation
1963
FOUR 1–2-day-old males of Culex pipiens were irradiated with a dose of 4,000 r. The mutant ‘red eye’ (r) was isolated from F3 cultures of two of the irradiated males (♂ II and ♂ IV). From male II, there were three red-eyed females which arose out of a single F2 brother–sister mating; from male IV, 80 red-eyed females and one red-eyed male from 14 F2 brother–sister matings. According to the experimental procedure, this means that at least one sperm from male II and at least fourteen sperms from male IV carried the mutation r. Thus, the same mutation was recovered in parallel from two irradiated males. The clustered appearance of the mutation in male IV was presumably caused by the occurrence…
Eradication of Culex pipiens fatigans through Cytoplasmic Incompatibility
1967
Culex pipiens fatigans is the chief vector of filariasis in south-east Asia. Urbanization has often caused the numbers of this mosquito—and with it the danger of filariasis infection—to increase alarmingly1. The natural vigour, tolerance and fast development of resistance to insecticides of this mosquito necessitate the development of other control methods, and cytoplasmic incompatibility2 seems to be an ideal means.
Effect of an Insect Growth Regulator (Halofenozide) on the Cuticular Hydrocarbons ofCulex pipiensLarvae
2013
The cuticular hydrocarbons of the fourth-instar larvae of Culex pipiens aged one and six days were analysed by gas chromatography and gas chromatography-mass spectrometry. The effect of an insect growth regulator (halofenozide = RH-0345) on the cuticular hydrocarbons was evaluated using newly moulted fourth-instar larvae of C. pipiens, at the lethal concentrations (LC50 = 12.58 and LC90 = 28.58 µ/l). A previous study revealed that RH-0345 is toxic to larvae of C. pipiens by induction of precocious larval moulting. Several cuticular hydrocarbons (CHCs) were identified and many of the other compounds remained unknown. Our data show that the CHC classes consisted of n-alkanes (C23-C29) and dif…
Inherited semisterility for control of harmful insects. II. Degree of sterility and types of translocations in the mosquito Culex pipiens L.
1971
Fur die Anwendung von Semisterilitat infolge von Translokationen zur Bekampfung schadlicher Insekten ist der Grad der Semisterilitat und die Art der zugrundeliegenden Translokation von Bedeutung. Von den bisher untersuchten 124 Translokationen hatten 101 einen Sterilitatsgrad zwischen 10 und 50%, 23 uber 50 bis zu 85%. Mit dem mannlichen Geschlechtsfaktor M gekoppelte Translokationen sind zur Zeit die fur die Praxis am nutzlichsten. Sie treten nicht so haufig auf als erwartet, machen aber doch rund 1/4 aller getesteten Translokationen aus. Es werden Grunde angefuhrt, weshalb M-gekoppelte Translokationen nutzlicher sind.
Studies on the laboratory mating habits of the mosquito Culex pipiens
2009
SYNOPSIS The variation in copulatory activity in three strains of Culex pipiens is investigated and the results are discussed in relation to genetic control of mosquito populations.
Vertical transmission of naturally occurring Bunyamwera and insect-specific flavivirus infections in mosquitoes from islands and mainland shores of L…
2018
Background Many arboviruses transmitted by mosquitoes have been implicated as causative agents of both human and animal illnesses in East Africa. Although epidemics of arboviral emerging infectious diseases have risen in frequency in recent years, the extent to which mosquitoes maintain pathogens in circulation during inter-epidemic periods is still poorly understood. This study aimed to investigate whether arboviruses may be maintained by vertical transmission via immature life stages of different mosquito vector species. Methodology We collected immature mosquitoes (egg, larva, pupa) on the shores and islands of Lake Baringo and Lake Victoria in western Kenya and reared them to adults. Mo…
Proposed use of spatial mortality assessments as part of the pesticide evaluation scheme for vector control
2013
Background: The WHO Pesticide Evaluation Scheme to evaluate the efficacy of insecticides does not include the testing of a lethal effect at a distance. A tool was developed to evaluate the spatial mortality of an insecticide product against adult mosquitoes at a distance under laboratory and field conditions. Operational implications are discussed. Methods: Insecticide paint, Inesfly 5A IGR (TM), containing two organophosphates (OPs): chlorpyrifos and diazinon, and one insect growth regulator (IGR): pyriproxyfen, was the product tested. Laboratory tests were performed using "distance boxes" with surfaces treated with one layer of control or insecticide paint at a dose of 1 kg/6 sq m. Field …
Effects of halofenozide (RH-0345) on cuticular hydrocarbons of mosquito larvae of Culex pipiens
2011
Poster; Insect cuticular hydrocarbons are known to have a protection and a pheromonal role. Quantitative changes in the cuticular hydrocarbons of Diptera occur over time and were used in a preliminary attempt to age-grade of mosquitoes. Halofenozide (RH-0345) is an insect growth regulator belonging to the class of non-steroidal ecdysone agonists. In a previous study, halofenozide was found to be effective against larvae of Culex pipiens L. (Diptera: Culicidae) and exerted its toxicity primarily by the induction of a precocious lethal molting (Boudjelida et al., 2005). In this study, newly molted 4th instar larvae of C. pipiens were exposed to halofenozide (23% EC) for 24 h at LC50 (12.58 µg…
Die Zuordnung der Koppelungsgruppen zu den Chromosomen bei der Stechm�cke Culex pipiens L.
1972
Die Numerierung der drei Koppelungsgruppen von Culex pipiens L. (Laven, 1967b) stimmt mit der bisherigen auf der Grose der Chromosomen beruhenden cytologischen Numerierung (Rai, 1963; Dennhofer, 1968) uberein. Das kurze Chromosomenpaar (I) tragt die geschlechtsbestimmenden Faktoren M bzw. m und die geschlechtsgekoppelten Gene der 1. Koppelungsgruppe. Das mittellange Paar (II) entspricht der 2. Koppelungsgruppe, der die Augenfarbmutation ruby (Iltis, Barr, McCelland und Myers, 1965) angehort. Die ungefahre Lokalisierung dieses Allels wird diskutiert. Das langste der Homologenpaare (III) ist der 3. Koppelungsgruppe gleichzusetzen, der z. B. die mannchenbegrenzte Palpenmutation kps (Laven, 195…