Mosquito Biology & Control

Objective هدف Name the biology of mosquitoes to appropriate control measures.

Overview مرور Life Cycle Behavior Control Measures

Importance of Mosquitoes Found worldwide except Antarctica Adult female mosquitoes require a blood meal for successful reproduction May transmit viruses, protozoa, and filarial disease agents Can have devastating impact, especially during military campaigns

Mosquitoes Diseases Mosquitoes are vectors of several important diseases: Malaria Dengue Yellow Fever Encephalitides (arboviruses)

Mosquito Growth and Development Complete Metamorphosis Egg, larva, pupa, adult Water is required for larval development BLOOD WATER

Egg Raft (Culex species)

Single Eggs (Anopheles species)

Mosquito Habitats Some require large bodies of still water with emergent vegetation (lake margins, rice fields) Flooded rice field

Mosquito Habitats Some require “dirty” water (lots of organic materials)

Mosquito Habitats Salt marshes (brackish water)

Mosquito Habitats Some require water in ditches, streams and other narrow vegetated watercourses (water does not move rapidly)

L - R: Bamboo, Pitcher Plant, Bromeliads Mosquito Habitat Water in certain plants L - R: Bamboo, Pitcher Plant, Bromeliads

Mosquito Habitat Water in tree holes

Mosquito Habitat Some attach themselves to plants and get their oxygen through the plant

Mosquito Habitats Water in artificial containers: cans, bottles, bird feeders, flower vases, and tires

Mosquito Habitat

Mosquito Growth and Development A mosquito larva hatches from an egg…..

Mosquito Growth and Development The larvae (“wigglers”) feed on microscopic plants and organic debris in the water; a few are predaceous (Toxorhynchites spp). Using a respiratory tube, the larvae obtain oxygen from the surface of the water (Anopheles, Culex, and Aedes) or from aquatic vegetation (Mansonia).

Mosquito Larvae Culex & Aedes Anopheles

Mosquito Larvae Mansonia species

Mosquito Larvae Mosquitoes have four larval stages Development completed in 4 to 10 days

Mosquitoe Pupae The pupae are also known as tumblers: quite active but do not feed they breathe through two trumpet-like tubes located on the thorax 2 to 5 days as pupae

Mosquito Adult Emerging

And flying away…..

Mosquito Behavior Defined: “The complex of mosquito actions and activities that meshes with, manipulates, and uses their environment” Mosquitoes do not think or reason as humans do -- they act/react instinctively to certain stimulus. We can use their behavior to facilitate surveying for them, trapping them, and killing them.

Break

Mosquito Behavior Feeding behavior Resting behavior Response to light Flight behavior Mating behavior

Feeding Behavior Males do not feed on blood. Most mosquito species require a blood meal for the adult female to complete the reproduction cycle. Males do not feed on blood. Almost all mosquitoes need a blood meal to supply protein for each batch of eggs. Some species can break down muscles for the protein to form one batch of eggs.

Feeding Behavior Mosquito females are “pool feeders” when they take a blood meal. They insert their straw-like proboscis into the host until it reaches capillary blood. They salivate into the wound, injecting materials to keep the blood from clotting, causing a sub-dermal blood pool to form. They pull the liquid blood pool through their proboscis to feed.

Culex species Aedes species Blood-Fed “Engorged” Culex species Aedes species

Feeding Behavior Males and females feed on plant nectar to obtain carbohydrates necessary for their energy requirements.

Host Specificity Many mosquitoes are host specific: Anthropophilic: feed exclusively on humans Other animals Domestic animals Wild animals Birds Or any mixture of the above. Domestic mosquitoes: found in close association with humans Problems arise when pathogens are transferred between hosts Mosquito feeding on bird now feeds on human

Host Attraction Attractiveness for mosquito based on an identifiable attribute of the primary host Carbon Dioxide (CO2): Attractive to many species; but all animals exhale CO2 L-lactic acid: Thought to be a human attractant; not considered to be important Octenol: Attractive to some, but not all spp. Other unidentified chemicals specific to host Colors, shapes, sizes, temperatures

Feeding Periodicity Feed only during certain times of a 24-hour cycle Knowing when they’re out feeding helps in targeting surveillance and control Diurnal -- during the day Crepuscular -- around sunrise and sunset Nocturnal -- during the night

Feeding Location Endophagic: prefer to feed inside of structures Rest in room corners, under beds, along roof, wait for host to come inside Exophagic: prefer to feed outside of structures Rest in shrubs, trees, pipes, feed on hosts when active outside

Resting Location Endophilic: prefer to rest inside after feeding Rest inside closets, behind curtains, in animal stalls, etc. Exophilic: prefer to rest outside after feeding Rest in vegetation, tree canopy, leaf litter, etc.

Attraction to Light Light attracts most mosquitoes, as it does most insects Attractiveness is most pronounced during night hours Some are so sensitive that they exhibit lunar periodicity More active with certain phases of the moon Increased activity w. full moon; decreased w. new moon However, not all mosquitoes are attracted to lights

Flight Range Distance able to fly varies from species to species Some tend to be weak flyers (</= 100 yds) -- Aedes aegypti and many peridomestic species Some are strong flyers (Aedes dorsalis, and most salt marsh breeders)...

Mating Behavior Adult males usually emerge from the pupal stage ~24 hours before females Male genitalia must rotate 180 degrees before they become functional -- a slow process A heavy emergence of males is often followed the next day by a heavy emergence of females

Mating Behavior In some species, males form mating swarms near the emergence site to mate with females as they emerge In some species, the adults mate singly, often near the blood host

Mosquito Control Control techniques vary with situation Large area management Limited recreational areas Residential Indoor Outdoor Field operational -- combinations of above

Control In/Around Buildings Reduce vegetation to reduce mosquito resting sites Outdoor residual pesticides applications in resting places Screens, caulking, other barriers Space spraying (“mosquito fogging”)

Wide Area Mosquito Management Can be a complex problem Involves separate sites and groups, and thus requires community involvement and administrative oversight needed Uses several control strategies, such as…

Health Education Education of the public to gain Understanding: People must understand the importance and process so they can and will contribute to it Support: People must support the process so they will clean up their areas, make their property accessible, and take personal precautions to avoid disease

Survey for Breeding Places Baseline survey must be made to locate the breeding sites of problem mosquitoes Oviposition sites (where eggs are laid) Larval habitats (where are they developing) Adult surveys (where are they hanging out and when)

Source Reduction Channel stagnant water streams Drain or fill if possible Remove vegetation that forms harborage Stock lakes and ponds with top-feeding minnows or mosquitofish (Gambusia)

Gambusia Mosquito fish

Chemical Management Larviciding Control the larvae before they become mobile blood-feeders Should be first line of attack Adulticiding Control the adults before they bite Proper pesticide must be used in the proper way!

Larval Control Use of an appropriate larvicide

Larval Control Biological Control: Stock with predators like this Toxorhynchites mosquito species or Gambusia fish

Summary Life Cycle Behavior Control Measures

Questions? سوالات Questions?