Aedes mosquito species in western Saudi Arabia

Abstract The Aedes Meigen (Diptera: Culicidae) mosquito species populations in the western region of Saudi Arabia, especially in and around Jeddah, are increasing, therefore increasing susceptibility of humans to the dengue virus. An extensive survey was carried out for one year, and four species were identified with the help of different pictorial keys available. The identification was based on morphological characteristics of adult female Aedes mosquitoes.


Introduction
Several mosquito species are of medical importance, but Aedes Meigen (Diptera: Culicidae) species are becoming the most important from a medical point of view all over the world. Aedes species (especially Aedes aegypti and Aedes albopictus) are vectors of arbo-viruses that infect various vertebrates, including humans. The most common arboviruses spread by Aedes species and infecting humans are the dengue fever virus, yellow fever virus, and chikungunya virus. The Aedes species of Saudi Arabia have been studied by several people, such as Mattingly and Knight (1956), Buttiker (1979Buttiker ( , 1981, Wills et al (1985), Abdullah and Merdan (1995), Al Zahrani (2001), Jupp et al (2002), Godsey Jr. et al (2003), Al Kherji (2005), Azzam (2006, and Al Ahmad et al (2011). Mattingly and Knight (1956) identified three species from the southwest only, namely Aedes aegypti, Aedes arabiensis and Aedes caspius. Buttiker (1979Buttiker ( , 1981 did not report-ed any Aedes species from this region. Wills et al. (1985) recorded Aedes caspius from the eastern part of the country. Abdullah and Merdan (1995)  There is no authentic record of Aedes mosquito fauna in the western region of Saudi Arabia. In an effort to better understand the fauna, we performed a comprehensive study of the aedine mosquitoes of the western region. The present work is the result of intensive surveillance for almost one year, from January 2010 to December 2010. The study revealed the presence of four species of Aedes in this region. Some of them have been reported in earlier studies from different parts of Saudi Arabia.

Material and Methods
Aedes species bite during the day and sometimes early night, and dawn and dusk are the peak biting times (WHO 2008). A thorough sampling was carried out by installing the light traps in various habitats in the western region of the country. Black Hole light traps (Rubicon, Inc., www.btglobal.co.kr) were used to attract the adult mosquitoes during the entire period of surveillance. Powered aspirators and flash torches were also used to collect mosquitoes from their different resting places.
Fourteen traps were installed in the city of Jeddah. The other towns selected for the surveillance were Al-Qunfudha, Al Qooz, Al Laith, Adham, Tharibaan, Khalees, Rabiq, and Al Kamil, and two traps were set in each city ( Figure 1). Live adult mosquitoes were brought to the laboratory for identification. After keeping them for 25 minutes in the deep freezer for immobilization, the samples were thoroughly searched for Aedes species, which were sorted out species wise and sex wise to determine the male:female ratio. Identification was done on the basis of adult female mor-phological characters with the help of different standard taxonomic keys and catalogues (Barraud 1934;Mattingly 1956, 1971;Knight and Stone 1977;Harbach andKnight 1980, 1981;Reinert 2000;Rueda 2004;Azzam 2006).

Results and Discussion
In the present study, four species of Aedes were identified from the western region of Saudi Arabia. Aedes (Stegomyia) aegypti (L.) was most commonly collected from almost all the locations of Jeddah and other towns. Aedes (Ochlerotatus) caspius (Pallas) was restricted in the regions that are close to sea. The highest number of Aedes (Ochlerotatus) caspius were collected from Bariman and South of Jeddah, and a few specimens were also collected from Rabiq and Al Qooz. Aedes (Ochlerotatus) vexans var. arabiensis (Meigen) was mainly concentrated in Al-Qunfudha and Al-Qooz, but a few specimens were also collected from Jeddah and other areas. Aedes vittatus Bigot was abundantly found in Al-Qooz and Al-Qunfudha. From the city of Jeddah, two female specimens of Ae. vittatus were collected from Um-Salam region only ( Table 1).
Correct identification of Aedes mosquitoes is necessary for effective control of Dengue fever and other arbo-viral diseases prevalent in this region. A simple guide with the diagnostic features is prepared to identify the Aedes mosquitoes of Western region of Saudi Arabia.