Host Plant Preference of Mansonia Mosquitoes

Human brugian filariasis, which is caused by Brugia malayi and B. timori , affects 13 million people in the oriental region (WHO 2002) and is most common in India and China (Ottesen et al. 1997). The most important vectors of B. malayi , in the endemic countries of South-east Asia, are different Mansonia species in the subgenus Mansonioides . The vectors of the parasite causing brugian filariasis in the Western Pacific and South-east Asian regions were reviewed by Chow in 1973 and Ramaliangam in 1975, while Ma. annulifera was reported by Iyengar in 1938, as an agent for transmission of B. malayi in Travancore, India. It has been observed that many species of mosquitoes, particularly under subgenus Mansonioides prefer habitats with well-developed beds of submerged, floating-leaf or emergent aquatic macrophytes because the vegetated regions protect them from physical disturbances and provide mechanical support and favorable conditions for oviposition. Unlike other mosquitoes, the larvae and pupae of Mansonia must attach their breathing tubes to the underwater roots, stems, or leaves of floating aquatic plants if they are to survive (Rajendran et al. 1989). Removal of such plants via mechanical, biological, or chemical control would therefore effectively prevent development of Mansonia . Control of brugian filariasis in most endemic countries has been limited to the use of chemo-therapy, either on the basis of an individual’s filarial symptoms or as mass drug administrations. The objective of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) is to break the transmission cycle between the mosquito vectors and human hosts. Thus knowledge on the distribution of mosquito species, their biology, habitats and control agents (mechanical, biological and chemical) is essential to develop integrated control methods against these insects. Although there have been a few relevant field studies and vector-control trials (Rajendran et al. 1993, Chang 2002, Ferreira et al. 2003), there have hardly been any operational-scale interventions against the vectors of B. malayi and B. timori . The objectives of the present study were to observe the host plant preference of different species of Mansonia mosquitoes during oviposition and to determine if the aquatic macrophyte species influences the survival of Mansonia larvae under laboratory conditions.