Chapter I INTRODUCTION A. Background of the Study
Mosquitoes are insect vectors responsible for the transmission of parasitic and viral infections to millions of people worldwide (Kovendan, et al., 2012). These vectors cause a major health hazard by transmitting vector-borne diseases especially in tropical countries. In a tropical country like the Philippines, dengue outbreaks have shown a very alarming number of cases. The National Epidemiology Center of the Philippines' Department of Health reports a total of 132,046 dengue cases from January to 13 October 2012. This is 24.92% higher compared to the same time period in 2011 (WHO, 2013). Of the total cases, 20.42% came from the National Capital Region (NCR), with highest contributors from Quezon City (7,754 cases), Manila (4,379 cases) and Caloocan City (2,967 cases). Next to NCR, Region III and Region IV-A registered the highest number of cases, which are 15.79% and 15.66% respectively, to the overall figure. These three areas, collectively characterized as highly urbanized and densely-populated, were consistently reported as the three most dengue endemic regions in the country over the past years (WHO, 2013).
Mosquito control, in view of their medical importance, assumes global importance (Subramaniam, et al., 2012). In the context of ever increasing trend to use more powerful synthetic insecticides to achieve immediate results in the control of the said vector, an alarming increase in the vector’s physiological resistance, its increased toxicity to non-target organisms and high costs are noteworthy (WHO, 1981).
Recently, stress is being laid on eco-friendly means of vector management. These include the use of natural products of plant origin as an alternative approach for mosquito control. The use of different parts of locally available plants and their various products in the control of mosquitoes