title: Development of Dirofilaria immitis and Dirofilaria repens in Aedes japonicus and Aedes geniculatus.
abstract: The mosquito-borne filarial nematodes Dirofilaria immitis and Dirofilaria repens primarily affect dogs but also cats, causing heartworm disease or subcutaneous dirofilariosis, respectively, and both may also cause zoonotic diseases in humans. Several mosquito species have been reported as competent vectors for these nematodes, but no data are available for the invasive mosquito species Aedes japonicus (Theobald, 1901). The objective of this study was to describe the development of both D. immitis and D. repens under standardised experimental laboratory conditions in mosquitoes.
  
  
  
  For this purpose, both a laboratory strain and field-collected individuals of the invasive mosquito species Ae. japonicus and, for comparative purposes, a laboratory strain of Aedes geniculatus, a rare indigenous species sharing habitats with Ae. japonicus, and of the tropical species Aedes aegypti were used. Anticoagulated microfilariaemic blood was fed at a density of 3000 mf/ml to mosquitoes with a hemotek system. Blood-fed mosquitoes were incubated at 27 °C and 85% relative humidity, and specimens were dissected under the microscope at pre-set time points to observe developmental stages of both Dirofilaria species. Additionally, real-time PCRs were carried out in some microscopically negative samples to determine the infection rates.
  
  
  
  In field-collected Ae. japonicus infectious L3 larvae of both D. immitis and D. repens developed, rendering this mosquito species an efficient vector for both filarial species. Additionally, Ae. geniculatus was shown to be an equally efficient vector for both filarial species. Aedes japonicus mosquitoes from a laboratory colony were refractory to D. immitis but susceptible to D. repens, whereas Ae. aegypti was refractory to both filarial species.
  
  
  
  To our knowledge, Aedes japonicus was for the first time shown to be an efficient vector for both D. immitis and D. repens, indicating that this invasive and locally highly abundant species may contribute to a transmission of filarial worms. The data emphasize the necessity to perform vector competence studies with local mosquito populations as basis for risk assessments. We further demonstrated that detection of filarial DNA in a mosquito species alone does not allow to draw reliable conclusions with regard to its vector competence.
authors.affiliation: National Centre for Vector Entomology, Institute of Parasitology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland. cornelia.silaghi@uzh.ch.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Silaghi
authors.affiliation: Department for Bacteriology and Parasitology, Croatian Veterinary Institute, Zagreb, Croatia.
authors.forename: Relja
authors.initials: R
authors.lastname: Beck
authors.affiliation: Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy.
authors.forename: Gioia
authors.initials: G
authors.lastname: Capelli
authors.affiliation: Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Montarsi
authors.affiliation: National Centre for Vector Entomology, Institute of Parasitology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mathis
mesh_terms: D000330:Aedes / Q000469:parasitology* / Q000502:physiology; D000818:Animals; D004183:Dirofilaria immitis / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000502:physiology; D060348:Dirofilaria repens / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000502:physiology; D004184:Dirofilariasis / Q000469:parasitology* / Q000635:transmission; D004283:Dog Diseases / Q000469:parasitology* / Q000635:transmission; D004285:Dogs; D005247:Feeding Behavior; D007303:Insect Vectors / Q000469:parasitology* / Q000502:physiology; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000502:physiology
keywords: Aedes aegypti; Aedes geniculatus; Aedes japonicus; Dirofilaria immitis; Dirofilaria repens; Dog; Intermediate host; Microfilariae; Vector