Identification of potential vectors of Dirofilaria immitis and Brugia pahangi (Spirurida: Filariidae): First observation of infective third-stage larva of B. pahangi in Culex quinquefasciatus (Diptera: Culicidae)

ABSTRACT

Information on the mosquito species that transmit canine filariosis is scanty. Hence, an experimental study was conducted to identify the potential vectors responsible for the transmission of D. immitis Leidy and B. pahangi Buckley & Edeson. A total of 367 mosquitoes belonging to six species containing both laboratory and field strains (i.e. Aedes togoi Theobald, Aedes aegypti Linnaeus, Aedes albopictus Skuse, Culex quinquefasciatus Say, Culex vishnui Theobald and Anopheles dirus Peyton & Harrison) were used in this study. All mosquitoes were artificially fed on either D. immitis or B. pahangi microfilariae (mfs) infected blood by using the Hemotek™ membrane feeding system. Out of 367 mosquitoes, 228 (64.9%) were fully engorged. After feeding on D. immitis (20%) and B. pahangi (33%) mfs positive blood, the mortality rates for Cx. quinquefasciatus were found to be slightly lower than that of other species of mosquitoes. On the other hand, majority of An. dirus were found to be incapable to withstand the infection of mfs as the mortality rates were relatively high (D. immitis = 71.4%; B. pahangi = 100.0%). Brugia pahangi was detected in Ae. togoi and Cx. quinquefasciatus with infection rates of 50% and 25%, respectively. Aedes togoi was the only species infected with D. immitis with an infection rate of 69%. Our results showed that Ae. togoi was an excellent experimental vector for both D. immitis and B. pahangi. This study also documented the observation of B. pahangi, for the first time in the head region of Cx. quinquefasciatus under a laboratory setting.

KEYWORDS:

• Brugia pahangi
• Dirofilaria immitis
• filaria
• mosquitoes
• vector

Acknowledgments

We would like to express our gratitude to the owners of the animal shelters and veterinarians for their assistance in sample collection. We are also grateful to Dr Jonathan Liew Wee Kent for his technical assistance in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Sample credit author statement

Wei Yin Vinnie-Siow: Methodology, Investigation, Writing-Original Draft, Formal analysis, Van Lun Low: Conceptualization, Investigation, Writing-Review & Editing, Supervision, Tiong Kai Tan: Investigation, Writing-Review & Editing, Supervision, Meng Li Wong: Investigation, Cherng Shii Leong: Investigation, Nazni Wasi Ahmad: Resources, Writing- Review& Editing, Yvonne Ai Lian Lim: Writing-Review & Editing, Supervision.

Additional information

Funding

This study was financially supported by the Higher Institution Centre of Excellence (HICoE) program (MO002-2019) and the Universiti Malaya research grant (PG098-2016A)