Vector competence of selected mosquito strains infected with dog heartworm (Dirofilaria immitis)

Mosquitoes are obligate developmental vectors of Dirofilaria immitis to dogs and other wild canids.  Worldwide over 70 species of mosquito are known to be vectors.  However, most publications only look at positive or negative infections. Herein we present a method to evaluate relative competence infection rates with a laboratory infection assay system.

          Aedes albopictus (UF2012) and Aedes aegypti (Orlando strain, UF subcolony) were infected with D. immitis via infected blood in a membrane feeding apparatus. Thereafter, mosquitoes were held at at one of three temperature schedules; constant 27 ºC, cycling from 14-27 ºC daily, or cycling from 14-25 ºC daily.  Mosquito mortality was measured daily and ability for a given mosquito species to develop infective stage D. immitis was measured as third stage D. immitis produced per mosquito using dissection.

          The mosquito strains evaluated were found to be refractory to development of infective stage D. immitis. Further experiments are planned to confirm this observation, with additional field strains evaluated.

          The D. immitis pathogen must cycle through mosquito hosts to develop. Currently, the evidence is not definitive for which vectors are responsible for the majority of infections in north central Florida. Additional planned experiments to improve vector incrimination will be discussed.