Development of Dirofilaria immitis (Leidy) in Aedes aegypti (L.) and Culex quinquefasciatus (Say) from Maceió, Alagoas, Brazil

Abstract

Dirofilaria immitis (Leidy, 1856) is a nematode that can be transmitted mainly by mosquitoes of the genera Aedes, Culex and Anopheles (KW Ludlam et al. 1970 JAVMA 157: 1354-1359. The susceptibility of mosquitoes to support development of D. immitis not only differs according to the vector species but also with regard to strains of a particular species (BM Christensen et al. 1984 J Invertebr Pathol 44: 267-274, CSB Apperson et al. 1989 Both mosquitos populations were originated from Maceió. Therefore, Ae. aegypti were reared at the insectary of Fiocruz, Recife, PE and the strain of Cx. quinquefasciatus was maintained at the insectary of the Universidade Federal de Alagoas in Maceió. Mosquitoes eggs were hatched in cubes containing dechlorinated water, larvae were reared with cat food (Whiskas ® ) and adults were kept at 27±1ºC and 70±10% R.H. A 4 years-old mixedbreed male dog naturally infected with D. immitis was used as the microfilariae (mf) donor (80 mf/ 20 µl blood) and one uninfected animal was used as control. Females 3-to 7-day-old of both mosquito species were allowed to feed on blood with anticoagulant via an artificial apparatus (LC Rutledge et al. 1964 Mosq News 24: 407-419) or directly on microfilaraemic and amicrofilaraemic dogs. Four different experiments were carried out and both mosquito species were fed simultaneously on the dog and via artificial apparatus between 4 p.m. and 5 p.m., during 30 min. Mosquitoes were dissected daily and D. immitis larvae were recorded. The developmental stages of the parasite were identified according to AER Taylor (1960 J Helminthol 34: 27-39). Mortality was recorded daily and the vector efficiency of mosquito species was determined as described by L Kartman (1954 Exp Parasitol 2: 27-78).Survival rates recorded with a total of 1,573 Cx. quinquefasciatus and 1,588 Ae. aegypti females fed on the microfilaraemic dog, were 30.6% and 20% respectively. For mosquitoes fed on the uninfected dog the values were 85% for the former and 46.4% for the latter species. The death of infected mosquitoes could be caused by the movement of large numbers of mf from the midgut to the Malpighian tubules as suggested by DR Hamilton and RE Bradley (1979 J Med Entomol 3: 305-306). The sausage form was observed on the 4th day and from days 8 to 9, the larvae grew longer and more narrow (L 2 ) reaching the infective larval stage (L 3 ) on the 10th day for Ae. aegypti and four days later for Cx. quinquefasciatus. Shorter developmental periods of D. immitis in a vector, as observed in Ae. aegypti, would favour disease transmission (KM Loftin et al. 1995 J Am Mosq Control Assoc 11: 90-93). Although both mosquito species ingested similar number of mf, the number of L 3 recorded per female was significantly higher in Ae. aegypti. In fact, no L 3 were recorded in Cx. quinquefasciatus which fed directly on the microfilaraemic dog and only one L 3 + Corresponding

Vector competence of Culex quinquefasciatus say from different regions of Brazil to Dirofilaria immitis

“…quinquefasciatus females were fed under conditions of microfilaraemia similar to those in our experiment. However, our values are slightly higher than that reported by Brito et al (1999) (i.e. VE = 0.0%) and lower than that reported by Loftin et al (1995), who determined a VE of 2.7% for the AL strain of Cx.…”

“…quinquefasciatus populations (χ 2 α5 = 6.66), with a variation of between 50.8% to 75% (Table III). Levels of survival were greater than those reported by Brito et al (1999), who only recorded a 30.6% survival in Cx. quinquefasciatus from Alagoas (AL) infected with D. immitis.…”

“…These findings are in agreement with studies on Cx. quinquefasciatus from other locations (Kartman 1953, 1954, Villavaso & Steelman 1970, Lowrie 1991, Loftin et al 1995, Brito et al 1999). In the case of Ae.…”

Vectorial competence of Aedes aegypti (Linnaeus 1762) Rio de Janeiro Strain, to Dirofilaria immitis (Leidy 1856)

“…quinquefasciatus and for that reason, it has better potential than Cx. quinquefasciatus as a vector of canine heartworm in Maceió (Brito et al 1999).…”

Morfología y citoquímica de cultivos celulares de Aedes aegypti (Diptera: Culicidae) y susceptibilidad a Leishmania panamensis (Kinetoplastida: Trypanosomatidae)

“…Es importante resaltar que A. aegypti no es vector de Leishmania, pero si de otras infecciones que afectan a los animales y al hombre; entre estas tenemos: dengue, fiebre amarilla y filariasis (Brito et al 1999, Harrington et al 2005. No obstante, líneas celulares derivadas de mosquitos han sido utilizadas como posibles modelos in vitro para el establecimiento y aislamiento de algunos patógenos, que no están necesariamente relacionados con sus hospederos naturales.…”