Mosquitoes in oklahoma
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Mosquitoes in Oklahoma. Dr. Russell Wright, Prof. Emeritus. General Biology of Mosquitoes. Insects that belong to Order DIPTERA which includes all the flies. Have four life stages: Egg -- laid on surface or edge of water. Larvae -- live only in water. Pupae -- live only in water. Adults.

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Mosquitoes in Oklahoma

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Mosquitoes in oklahoma

Mosquitoes in Oklahoma

Dr. Russell Wright, Prof. Emeritus


General biology of mosquitoes

General Biology of Mosquitoes

  • Insects that belong to Order DIPTERA which includes all the flies.

  • Have four life stages:

    • Egg -- laid on surface or edge of water.

    • Larvae -- live only in water.

    • Pupae -- live only in water.

    • Adults


Mosquitoes in oklahoma

Eggs

  • Laid on singly on surface or edge of water.

  • Some species lay eggs in rafts on surface of water.

  • Some sp. hatch 24-36 hrs.

  • Some hatch after one, two or three years.

  • Over wintering stage for some species


Larvae

Larvae

  • Four stages: 1st, 2nd, 3rd, 4th instars.

  • Called “wrigglers”,very active, come to surface for air.

  • Total length 6-12 days. Some species even weeks.


Pupae

Pupae

  • Stage that changes from larvae to adult.

  • Called “tumblers” very active, come to surface for air.

  • Stage lasts from 3-6 days.


Adult male

Adult (Male)

  • Emerges first

  • Feeds on nectar sources for energy.

  • Mates within 3 to 7 days and dies


Adult females

Adult (Females)

  • Emerges and feeds on nectar.

  • Mates, usually only once.

  • Searches for blood meal.

  • Needs blood meal to develop eggs.

  • 1-5 blood meals over life of 7 to 28 days.


Mosquito life cycle

Mosquito Life Cycle


Mosquito species present in oklahoma

Mosquito Species Present in Oklahoma:

  • Approximately 60 known species in Oklahoma. Over 230 species in U.S.

  • Usually only 6-8 species will be a nuisance pest in any given area.


Genus and species

Genus and species

  • Every species is more different from each other genetically than you and I are from any other human on earth.

  • So I will need to use at least Genus names, sometimes species as I refer to biology.

  • Think of these names as the folks you know as Jane, Linda, Ann , Tom. Dick, Harry etc.

  • However if you think of any of your friends by these names, don’t tell them I told you to do so.


Classification based on larval habitat

Classification Based on Larval Habitat

  • Flood Water Mosquitoes

  • Permanent Water Mosquitoes

    • Permanent Pool Group

    • Transient Water Group

  • Container Mosquitoes


Larval habitat

Larval Habitat

  • Important to know which mosquitoes cause problems and when.

  • Identify larval habitats based on adults present.

  • Most effective to find and map larval habitats and eliminate or treat in this stage.


Flood water mosquitoes

Flood Water Mosquitoes

  • Mosquitoes in Genera Aedes, Ochlerotatus, and Psorophora

  • Some species from these three genera are the most important pest species.

  • Bite humans, livestock, pets. And can have very large populations in spring and early summer.

  • Do not believe that most vector WNV


Flood water mosquitoes cont

Flood Water Mosquitoes (cont.)

  • Eggs are laid on the soil surface at the edge of standing pools of water that are left from heavy rains or floods.

    • Often woodland pools; roadside ditches or low areas along creeks rivers that collect flood water.

  • Eggs hatch when flooded by run off from heavy rains or flood water.


Flood water mosquitoes cont1

Flood Water Mosquitoes (cont.)

  • Eggs are over wintering stage. In most cases must spend winter in egg case, called diapause stage.

  • Can survive in egg stage for several years until flooded.

  • However, can have different hatches within several days if increased water levels hatch new eggs.


Flood water mosquitoes cont2

Flood Water Mosquitoes (cont.)

  • Adult populations peak in late April, May, and June, some species hatch with late summer fall rains .

  • Adults die quickly during hot weather.

  • Any flooded pools usually dry up too fast to support larvae in hot weather.

  • Females most active around sunset or in shady areas when disturbed.


Floodwater pool aedes vexans

Floodwater Pool – Aedes vexans


Floodwater pool aedes vexans1

Floodwater Pool – Aedes vexans


Permanent water mosquitoes permanent pool group

Permanent Water MosquitoesPermanent Pool Group

  • Genera Anopheles, Coquillettida, Mansonia some Culex sp.

  • Found in quiet bodies of freshwater with sunlight, much surface vegetation and very little wave action.

  • Shallow edges of ponds, some lakes backwaters of rivers even slow moving streams.

  • Never in main lake or pond areas with much wave action.


Permanent pool group cont

Permanent Pool Group (cont.)

  • Anopheles lay eggs singly on surface of water, each egg with a float.

  • Eggs hatch in 24-36 hrs. Many generations a year tend to peak mid late summer

  • Adults over winter triggered by photoperiod.

  • Deep south perhaps cycle can go all year, slower in winter.


Permanent pool group cont1

Permanent Pool Group (cont.)

  • Genera Coquillettidia and Mansonia

  • Mansonia mosquitoes lay eggs in groups attached to plant stems underwater; Coquillettidia in rafts onwater surface.

  • Larvae insert breathing siphon into plant and takes oxygen directly from plant tissues. Cattail marshes and similar type water.

  • Appear to have one prolonged generation per year and at least in south over winter in larval stage.

  • Not much of a nuisance pest.


Permanent water mosquitoes transient water group

Permanent Water MosquitoesTransient Water Group

  • Genera Culex and Culiseta

  • Canals, long standing ground pools or roadside ditches, catch basins, storm sewers , clogged sewers long standing irrigation pools, water often becomes very foul polluted for some species others need fairly clean water.

  • These mosquitoes lay eggs in rafts on the surface of the water.

  • Eggs hatch within 24-36 hours.


Transient water group cont

Transient Water Group (cont.)

  • These mosquitoes normally over winter in the adult stage.

  • Adults emerging in late summer or fall do not search for a blood meal, but mate and female searches for sheltered areas to spend winter.

    • Caves, burrows, sewers, basements etc.

  • Populations low in spring peak in mid to late summer. Vary some with species.


Culex spp laying eggs

Culex spp. Laying Eggs


Transient water group cont1

Transient Water Group (cont.)

  • Populations of these mosquitoes low in spring.

  • Takes awhile to build large populations.

  • Peak abundance July-October.

  • Many species prefer birds as hosts.

  • Are often best vectors of viruses.

  • Bite more readily at night.


Transient water mosquito habitat

Transient Water Mosquito Habitat


Container mosquitoes

Container Mosquitoes

  • Certain species in 5-6 Genera

  • In nature larvae live in tree holes, rock pools even leaf axils.

  • Many species now associated with man made containers or materials that hold water.

    • Tires, cans, buckets , birdbaths, gutters, pet water dishes, plant container bottoms that catch water, even cans, paper cups etc.


Typical container mosquito habitat

Typical Container Mosquito Habitat


Asian tiger mosquito

Asian Tiger Mosquito

  • Aedes albopictus

  • Larvae in containers of any size.


Aedes albopictus eggs in container

Aedes albopictus Eggs in Container

  • Efficient container breeder utilizing available sources.

  • Eggs laid on surface of water, on sides of container, and on stick.

  • Immediate egg hatch of some eggs, delayed hatch for others.


Asian tiger mosquito1

Asian Tiger Mosquito

  • First found in OK 1990-91, Tulsa, SE Counties.

  • By 2000 was found in all counties we surveyed.

  • Most important pest in most areas.

  • Bites in mid to late afternoon.

  • Abundant from mid June through Sept.


Distribution of asian tiger mosquito in oklahoma

1990-91

Thru 2000

Distribution of Asian Tiger Mosquito in Oklahoma


Mosquito species of greatest concern

Mosquito Species of Greatest Concern

  • Belong to Genus Culex

  • Include C. pipiens/quinquefasciatus, southern house mosquito most likely vector

  • C. restuans, C. salinarius, C. tarsalis.

  • Note: all are permanent water mosquitoes, populations peak in summer through fall at same time virus activity peaks

  • All prefer to feed on birds.


Possible wnv vector species in oklahoma

Possible WNV Vector Speciesin Oklahoma

  • Bridge vectors to humans & horses.

  • Culex tarsalis – Cx. salinarius Permanent transient water but not very stagnant

  • Aedes vexans –floodwater; spring through mid summer

  • Aedes albopictus

  • Ochlerotatus triseriatus. Oc. hendersoni

    • Container or tree hole species


Surveillance

Surveillance

  • Knowledge of the mosquito species in a given area and relative abundance is necessary in planning control measures.

  • Some species do not vector WNV, control not as important.

  • Accurate records must be kept of surveillance locations.

  • Species I.D. is essential.


Larviciding

Larviciding

  • Controlling mosquito larvae most effective control measure because life stage is confined to aquatic habitat.

  • Water management by drainage or source reduction.

  • Larvicides can be used if drainage not available or adequate.

  • Not as practical in Oklahoma until we have identified larval sites.


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