There are more than 80 mosquito species in Florida with 50 of these known to occur in Indian River County. Each county has several species that are a nuisance and others that have the potential to transmit mosquito–borne diseases. As such, it is important to identify which species are prevalent in the District, detect the arrival of invading species or monitor population numbers before implementing control measures. IRMCD monitors the aquatic larval stages of mosquitoes as well as populations of adult mosquitoes, depending on surveillance goals.
Adult mosquitoes may be monitored for a variety of purposes:
- to determine where adults are most numerous;
- to define the nature and extent of the mosquito problem;
- to substantiate service request claims of a mosquito problem;
- to obtain data necessary to comply with state rules and regulations for justification of treatments
- to determine the effectiveness of source reduction, larviciding, and adulticiding control methods;
- to evaluate potential for mosquito-borne disease transmission (refer to Arbovirus Surveillance for more information).
Adult mosquitoes are usually monitored by use of specialized traps or by landing rate counts. In some remote areas the District utilizes Mosquito Magnet traps to assess population numbers within a given area. Other kinds of traps may target particular groups of mosquito species. Regardless of type, traps may be baited with carbon dioxide, octanol or include a small light source as attractants. Trap collections are collected daily, sorted out by species and counted. These trap counts can be utilized to assess changes in adult populations and determine whether control measures are needed, such as sending a spray truck (adulticiding).
Staff also conduct landing rate counts throughout the District to assess populations of adult mosquitoes. This technique consists of counting the number of mosquitoes that land on a person in a given amount of time, typically in one minute. This method provides an estimate of the biting pressure within a given area and can be used to justify control measures/treatment.
Much of the District’s surveillance efforts are focused on the aquatic immature mosquito stages, particularly in the marshes and wetlands adjacent to the Indian River Lagoon. Intense daily inspection of these habitats allows inspectors to identify areas where salt marsh mosquitoes have hatched, allowing treatment with larvicides to kill them before they can develop into biting adults.