Human beings are the major source of feed for many species of urban mosquitoes and therefore human landing collection provides valuable index of population density 1617. The biting behaviour of Cx. quinquefasciatus was studied in a house, located in Jaihindpuram, Madurai, Tamil Nadu, India (Figure 1). This area is known for the abundance of Cx. quinquefasciatus. Therefore this mosquito was selected in the present study to assess the biting behaviour. The landing mosquitoes for biting were collected during the period from July 2006 to November 2006 to assess the biting behaviour in four different sites. The collections were made in the first floor and second floor and also in the indoor and outdoor conditions. Adult mosquitoes attracted to human being (25 years old female) were collected from the collection sites for 24 hours continuously in order to determine whether Cx. quinquefasciatus exhibits exophagic or endophagic behaviour and also to note the existence of the vertical stratification in the biting behaviour. As per the methodology of Pandian and Chandrashekaran 18, the adult female mosquitoes landing on exposed parts of the leg for biting were collected with a small transparent plastic container with cap at the time of probing on the human beings. For catching of each mosquito, individual plastic container was used. Hourly collected mosquitoes were put in a separate labeled polythene bag. A mechanical aspirator was used to collect adult mosquitoes using flash lights during 18-06 hours. The collected specimens were brought to the laboratory and identified with standard keys 192021. After identification the hourly catches of mosquitoes were plotted to understand the biting pattern. As this mosquito species was dominant in numbers and the other species were negligible, this was alone considered. The data were collected twice and the mean values were calculated.

Mosquitoes are not only pests; they are also capable of transmitting several diseases like malaria, encephalitis and yellow fever. There are more than 2500 species of mosquitoes in the world. Recently, mosquito-borne diseases are threatening the world. Mosquitoes transmit diseases to more than 700,000,000 people each year. No single method will provide adequate control of mosquitoes and so a combination of biological, chemical and environmental management and repellents is needed at present to attack mosquitoes. In this context, the knowledge about the behaviour of mosquitoes and suggestion of suitable alternative methods are desirable. Cx. quinquefasciatus is found predominantly in the urban areas and it breeds enormously in all the available habitats and multiply in large numbers 222324.

The identification of the pattern of biting rhythm of this mosquito is a pre-requisite for the testing of efficacy of both synthetic and plant derived repellents. This mosquito feeds mainly during the dark phase of the day. Though it feeds throughout the night, the peak of biting activity was recorded at three times, one soon after the dusk, another one at the middle of the night and the last one just before the dawn. The occurrence of multiple peaks in the biting activity is a unique feature. Peaks were noticed during 20-21 h during September and October while they were noticed during morning hours in August and November. Least values were observed during noon in all the six months (Figure 2).This mosquito exhibits exophagic behavior. Only in July the peak was seen in indoor conditions while in other other months peaks were observed in outdoor conditions. Maximum biting was noticed during 04-05 h in September, October and November (Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7). This mosquito exhibited a vertical stratification in its biting behaviour by feeding predominantly in the first floor and to a lesser extent in the second floor. Biting was more in the first floor than that of second floor during the six months. Maximum biting was recorded during 20-21h in August, September and October. In July it was during 18-19h and 04-05h in November. Cx. quinquefasciatus revealed the nocturnal biting pattern in the present study, that means the biting activity was more in night time than the day time. Along with that, a mild biting activity was also observed in the early morning time. The predominant nocturnal biting pattern showed by Cx. quinquefasciatus in the study site correlated with the observations of Birley and Rajagopalan 25 and other similar kind of studies carried out at various time periods 26272829. The mosquito showed a peak biting density between 18 and 20h in Nigeria which was demonstrated by the crowding of local people in outdoor till 22h in the study area 30.

The temperature is always having inverse relationship with the population density of mosquitoes, whereas, rainfall is always having a positive relationship with the abundance of Cx. quinquefasciatus. This coincides with the findings of Lindsay et al. 31 and Gajanana et al. 32. This is explicable as the rain creates more sites for mosquito breeding. The seasonal abundance of mosquitoes has been studied in several endemic areas including Pondicherry in India 33. Other than climate and availability of breeding places, the factors like environmental conditions (odours from other sources, prohibitive wind speeds); physiological conditions (circadian phase, gonotrophic stage and nutritional status); and the mosquito genotype (olfactory proteins involved in response to external stimuli) are also having their influence on the population density. All these factors have been reported to affect the responsiveness of mosquitoes 3435. For example, the vectors make use of human activities effectively for their breeding and perpetuation. The breeding habit of Cx. quinquefasciatusis an interesting phenomenon where they use to exploit the food processing activity of human beings in the Imo River Basin study areas, whose favorable food is fermented cassava, Manihot utillissema. In these areas, Cx. quinquefasciatus use the pots of fermenting cassava as their breeding site. This food processing strategy is practiced almost throughout the year and that ensures the breeding of Cx. quinquefasciatusall over the year. This kind of human practices alter the pattern of transmission of diseases in the tropics 363738.

The establishment of insecticide resistance in major vectors reveals that single vector control operations are not suitable for the effective control of disease transmitting vectors in human beings. In this connection, the ideal one is integrated vector management that will permit the participation of individuals, communities and governments to understand the disease burden in the combination of a number of options available. Through that, people may ensure their safety against the prevalence of diseases 39. The findings of this study revealed that different places of human dwelling elicited different responses which affected the behavioural landing site preference of Cx. quinquefasciatusin their attempt to feed on their host blood. The density of mosquitoes was abundant in the ground floor than the top floors and it exhibited a peak during midnight 40. The vertical stratification of the mosquitoes was recorded. The density of mosquitoes was more in outdoor than indoor. It showed the exophilic behaviour in the feeding pattern. In the present study, there were several peaks of biting patterns observed i.e., one soon after the dusk, another one at the midnight and the last one just before the dawn. In conclusion, it is mandatory to take proper precautionary measures in order to protect humans from the dreadful mosquito-borne diseases and their nuisance. Hence it is recommended to avoid the mosquito bites by avoiding infested areas, wearing protective cloth and applying appropriate mosquito repellents in order to safeguard from the mosquitoes and their ill effects.