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Mosquito License TrainingMosquito License Training

Category 41Category 41

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Chapter 3. Mosquitoes as Vectors of Diseases

1. Discuss the importance of mosquitoes besides their pure nuisance activity.

Mosquitoes are not only a nuisance; they are a serious health threat to people and their pets and livestock. With just one bite, mosquitoes can transmit West Nile Virus and other viruses that cause encephalitis. They can also transmit heartworm disease to dogs and cats.

2. Name the major diseases the mosquitoes typically transmit in Georgia.

Most Common Arboviral Diseases in Georgia• West Nile Virus• Lacrosse Encephalitis• Eastern Equine Encephalitis• Internationally acquired Dengue

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Diseases Carried by Mosquitoes*Eastern equine encephalitis HeartwormJapanese encephalitis ChikungunyaLa Crosse encephalitis Barmah Forest virus St. Louis encephalitis Kunjin virus West Nile virus Ross River feverWestern equine encephalitis O'Nyong-nyong feverDengue Fever/DHF Yellow FeverMalaria Murray Valley encephalitis virus Rift Valley FeverVenezuelan equine encephalitisElephantiasis/Filariasis

*a partial list

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What is encephalitis?• An acute inflammation of

the brain. • Encephalitis with

meningitis is known as meningoencephalitis.

• Symptoms include headache, fever, confusion, drowsiness, and fatigue.

• More advanced and serious symptoms include seizures or convulsions, tremors, hallucinations, and memory problems.

• Encephalitis is most often caused by a viral infection.

3. Recognize and understand the importance of the term encephalitis.

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West Nile Virus

Most human cases occur in late summer and in autumn

1◦ Vector – Culex quinquefasciatus

Highest Risk – the elderly

Case Fatality Rate ~3 to 15%

Yearly Occurrence (so far)

West Nile virus was first isolated from a febrile adult woman in the West Nile District of Uganda in 1937.

WNV first appeared in North America in 1999 in New York City.

WNV was first detected in Georgia in 2001.

other possible vectors:Culex sppAedes albopictusOchlerotatus spp

4. Describe the recent history of WNV in the US.5. Describe the typical transmission cycle of WNV.6. Name the primary vector of WNV in Georgia.

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WNV is not the only mosquito-borne disease found in Georgia.

We also have:

LaCrosse Encephalitis (LAC) – small mammals

Most human cases occur in July, Aug, & Sept

Vector - Oc triseriatus, the treehole mosquito

Highest Risk – children under 15

Case Fatality Rate ~1%

St Louis Encephalitis (SLE) – birds

Most human cases occur in late summer and in autumn

Vector – Culex spp

Highest Risk – the elderly

Case Fatality Rate ~10%

Eastern Equine Encephalitis (EEE) - birds

Most human cases occur in late summer and in autumn

Vector – Culiseta melanura; a variety of bridge vectors

Highest Risk – young children and the elderly

Case Fatality Rate >50% Horse Fatality Rate 90-95%

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Eastern Equine EncephalitisEastern Equine EncephalitisEastern equine encephalitis virus (EEEV) is maintained in a cycle between Culiseta melanura mosquitoes and avian hosts in freshwater hardwood swamps. Cs. melanura is not considered to be an important vector of EEEV to humans because it feeds almost exclusively on birds.

Transmission to humans requires mosquito species capable of creating a "bridge" between infected birds and uninfected mammals such as some Aedes, Coquillettidia, and Culex species

7. Understand the importance of EEE to mosquito control operators.8. Describe the EEE transmission cycle.

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LaCrosse Encephalitis

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MalariaMalaria

9. Name the most important disease transmitted by mosquitoes world-wide.

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Malaria affected 30 percent of the population in the region when the TVA was incorporated in 1933.

The Public Health Service played a vital role in the research and control operations and by 1947, the disease was essentially eliminated.

The U.S. Tennessee Valley Authority (TVA) - The Integration of Malaria Control with

Economic Development (1933)

Mosquito breeding sites were reduced by controlling water levels and insecticide applications.

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DengueDengue is a viral disease, commonly called "breakbone fever."

Dengue epidemics were common in the 1800s and early 1900s in the U.S.

The last major epidemic of dengue in the continental US occurred in Louisiana in 1945 with 62 confirmed cases, but authorities estimated that there were probably several hundred unapparent and/or unreported cases.

In 1980, Texas recorded 23 locally acquired cases of dengue, and new cases occurred sporadically until 1999, when 18 cases were reported.

Although dengue is not endemic now in most of the US, potential vectors are present in the southern US, and the virus is commonly reported in people entering the country from endemic areas of the tropics.

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What is Yellow Fever?

Rural cycle

Urban cycle

Sylvatic cycle

Initial symptoms include fever, headache, vomiting and backache.

As the disease progresses, the pulse slows and weakens, and bleeding of the gums and bloody urine occur.

Jaundice may also occur.

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HeartwormHeartworm• infection rates:

– 80% in dogs over 2.5 years old– 100% in dogs over 5 years old

• cats can also be infected • in humans, worms are unable to mature• wild canids are the enzootic vector• the primary vector is Cx quinquefasciatus• dogs should receive prophylaxis to prevent infection

and death

10. Name the most important veterinary disease transmitted by mosquitoes in Georgia.

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HeartwormHeartworm

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Heartworm Economic IssuesHeartworm Economic Issues

• Prevention Cost, US - $1.2 billion• Prevention Cost, Georgia - $60,000,000• Treatment - $1000 per case

11. Recognize the economic importance of dog heartworm in Georgia.

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SPECIES LARVAL HABITAT HOST PREFERENCEOVER-

WINTERBITING TIME FLIGHT RANGE

Aedes albopictus AC, TH Humans, Large Mammals Egg D 100 to 300 yards

Aedes vexans FW, GP, IP Humans, Large Mammals Egg C, N 1 to 15 miles

Anopheles quadrimaculatus FW, GP, LM, RP Large Mammals Adults C 1/2 to 1 mile

Coquillettidia perturbans FS, RE, LM, DD Humans, Mammals, Birds Larvae C 1 to 5 miles

Culex nigripalpus GP, FW, DD Humans, Large Mammals Adults C 1/2 to 1 mile

Culex quinquefasciatus AC, SCB, GRP Birds, Humans, Mammals Adults C, N 1/4 to 1/2 mile

Culex restuans WP, GRP, DD Birds, Humans, Mammals Adults C, N 1 to 2 miles

Culex salinarius AC, GP, LM, FS Birds, Humans, Mammals Adults C, N 1/4 to 5 miles

Culiseta melanura FS, WP Birds Larvae C, N 1/2 to 2 miles

Ochlerotatus canadensis WP, DD, FSSmall Mammals, birds, reptiles Egg C, D 0 to 1/4 mile

Ochlerotatus japonicus AC Humans, Mammals, Birds Egg, Larvae D

Ochlerotatus sollicitans SM Humans, Birds Egg C, D 5 to 100 miles

Ochlerotatus taeniorhynchus SM Humans, Birds, Mammals Egg C, N, D 2 to 40 miles

Ochlerotatus triseriatus TH, AC, Red MapleHumans, Mammals, Squirrels Egg C 1/2 to 1 mile

Mosquito Biological DataMosquito Biological Data

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KEY TO HABITATS BITING TIME

AC-Artificial Containers

RE-Rooted Emerged Vegetation

C-CREPUSCULAR (DUSK AND DAWN)

DD-Drainage Ditches RF-Rice Fields D-DAY

FS-Freshwater Swamps

RT-Retention/Detention Ponds N-NIGHT

FW-FloodwatersSCB-Sewage Catch Basins

WP-Woodland Pools SM-Salt Marshes

GP-Grassland Pools TH-Tree Holes

GRP-Ground Pools TP-Temporary Pools

IP-Irrigated Pastures

TRP-Temporary Rain Pools

LM-Lake Margins P-Ponds

http://www.gamosquito.org/resources/biodata.xls

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Mosquito MythsMosquito Myths

Can AIDS be transmitted by mosquitoes?

There is no scientific evidence to suggest that this is possible.

Is it impossible? It is safe to say that the involvement of blood-feeding insects and arthropods is biologically insignificant if it occurs at all.

12. Recognize that AIDS is not transmitted by mosquitoes.

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Chapter 4.Integrated Mosquito Management

1. Name the five aspects of Integrated Mosquito Management.

a) Education / Communication

b) Surveillance / Mapping

c) Source Reduction

d) Larviciding

e) Adulticiding

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The 4 overlapping aims of mosquito control are to:

• prevent mosquito bites, • keep mosquito populations at acceptable densities, • minimize mosquito-vertebrate contact, and • reduce the longevity of female mosquitoes.

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Education/Communication

• The public should:– Recognize the problem– Recognize the cause of

the problem– Know how to correct

the problem– Know how to assist

mosquito control

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Working with the Public

• It is important to follow up on complaints in order to:

– Learn of problem areas– Learn what control measures are acceptable to

area residents– Obtain feedback on effectiveness of control

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Public Relations

• person-to-person contact– phone calls– letters– home visits

• group contacts– lectures– school visits

• mass media activities

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2. Discuss the importance of sanitation in controlling container breeding mosquitoes around homes.

Most Mosquito Problems Start at Home: Home Owner Checklist

1. Cover or properly dispose of any water-holding containers.2. Fill in or drain low places in yard.3. Keep ditches, drains, gutters, and culverts free of weeds and

trash.4. Cover trash containers to keep out rain water.5. Repair leaky pipes

and outdoor faucets.6. Empty wading pools

weekly and store indoors when notin use.

7. Take proper careof the backyardpool.

8. Fill in tree holesand hollow stumps.

9. Change water inbird baths weekly.

10. Keep grass cut and shrubs trimmed to eliminate adult mosquitoresting sites.

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3. Describe the proper technique for using insect repellents.

The 5 D’s of DISEASE PREVENTION:

Dusk Avoid being outdoors whenDawn mosquitoes are most active.Dress Cover your skin with protective clothingDEET Protect bare skin with mosquito

repellent.Drain Empty containers holding stagnant water in which mosquitoes breed.

Credit: J.Rutherford, Monroe CHD

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1. DEET (N, N-diethyl-3-methylbenzamide) is probably the best insect repellent, repelling both mosquitoes and ticks.

2. It is sold under numerous brand names (Off ®, Cutter ®, etc.) and comes in lotion, spray and many other forms.

3. Concentrations of DEET range from about 5% all the way up to 100%.

4. After a certain point (~35%), though, higher concentrations do not guarantee greater protection.

5. The American Academy of Pediatrics recommends that repellents used on children contain no more than 10% DEET.

6. As with all repellents, DEET-based products should be applied only according to the directions on the product label.

REPELLENTS

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1. Picaridin has effectiveness comparable that of DEET. 2. Products with picaridin can be expected to provide better and longer-lasting

protection than plant-based repellents. 3. Cutter Advanced® contains picaridin as an active ingredient.

1. Oil of lemon eucalyptus (or PMD) has been tested against mosquitoes found in the US, and provides protection similar to repellents with low concentrations of DEET.

2. Repel® Lemon Eucalyptus contains this active ingredient.

Other RepellentsPICARIDIN

PMD

1. IR3535 is labeled for use against mosquitoes, ticks, and biting flies. 2. IR3535 is somewhat less effective than DEET against mosquitoes. 3. This repellent is currently available exclusively through the Avon Corporation

as Skin-So-Soft Bug Guard plus IR3535.

IR3535

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PERMETHRIN

1. Permethrin is a pesticide rather than a repellent.

2. It is not for use on the skin, but is intended for clothing.

3. Permethrin products are sold in lawn, garden or sporting goods stores under names such as Permanone Repel ®.

4. Permethrin can retain its potency for at least two weeks — even through several launderings.

5. The combination of Permethrin-treated clothing and DEET-treated skin creates almost complete protection against mosquito bites.

6. In field trials conducted in Alaska, Permethrin-treated clothing and 35% DEET on exposed skin provided greater than 99.9% protection.

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Safe Repellent Use

DO • Use aerosol or pump sprays for treating skin and

clothing; these products provide an even application.

• Use liquids, creams, lotions or sticks to more precisely apply the product to exposed skin.

• Wash DEET-covered skin with soap and water after outdoor activity.

• Keep insect repellents out of the reach of children at all times.

DON’T • Apply to eyes, lips or mouth, or over cuts, wounds

or irritated skin. • Over-apply to the skin, or saturate clothing. • Apply to skin beneath clothing, or to skin that is not

exposed. • Apply more or more often than recommended on

the product label

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5 Steps to an Effective IMM Program:

1. Education / Communication

2. Surveillance / Mapping

3. Source Reduction

4. Larviciding

5. Adulticiding

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Knowing what mosquito species are present andwhere they are breeding is essential to a well-plannedmosquito control program.

SURVEILLANCESURVEILLANCE

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4. Explain why the use of maps is so important to a comprehensive mosquito control program.

Reasonably accurate and comprehensive maps are essential in conducting a mosquito control operation.

•Maps provide info for field survey and control activities•Maps assist in program evaluation and reporting

Master maps should contain:•treatment areas•potential flight range of mosquito species from breeding sites•populated areas•mosquito surveillance sites•habitats•vector-borne disease issues•elevation•street information•water elements

5. Understand the concept of larval and adult surveillance.

Gravid Trap

Light Trap

Mosquito Surveillance

Mosquito Surveillance

Mosquito surveillance is the cornerstone of mosquito control.

No mosquito control program can operate effectively without a surveillance program.

Mosquito surveillance can reveal:

•The species of mosquitoes that are active in a community

•The presence of disease vector species

•The presence of mosquitoes infected with arboviral diseases

•The breeding habitats of the local species

•The size of the local mosquito population

•When to apply pesticides to control the mosquito population.

Benefits of Mosquito Surveillance:Benefits of Mosquito Surveillance:

•Provides data for local risk assessment

•Assists in making mosquito control decisions

•Saves money by fine-tuning control efforts

•Monitors for presence of arboviruses

•May provide early detection for other introduced arboviruses

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What Kind of Trap Should You Use?

depends on your need and your budget

Oviposition Trap

• Used to collect eggs from container breeding mosquitoes

• Gravid females lay eggs just above the waterline• Eggs are hatched and reared to 4th instar for identification

Larval ID Equipment

http://www.rci.rutgers.edu/~insects/dipping.htm38

LANDING COUNTS

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6. Name 3 types of adult surveillance.

Gravid Traps

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Light TrapLight Trap

Other Trapping Methods• Insect sweep net• Bait trap• Truck trap• Resting collections• New Jersey light traps

7. Explain why source reduction is the best way to control mosquitoes.

Source reduction ranges from the simple overturning of a discarded bucket or disposing of waste tires to complex water‑level manipulations in marshes.

The removal or reduction of mosquito breeding habitat is often the most effective and economical long‑term method of mosquito control.

Water management.

Prevention of breeding can be accomplished by removing surface waters from productive sites to reduce oviposition, manipulating shoreline water levels or flooding areas in which mosquitoes oviposit in the soil.

•open marsh water management •impoundment management

8. List 3 modes of action for commonly used larvicides.

Reduction of breeding sites is the most effective intervention for controlling mosquito populations.

Because many sites cannot be controlled by source reduction, the next most effective intervention is mosquito larviciding.

Several materials in various formulations are labeled for mosquito larviciding, including:

•biological control agents (Diptera‑specific bacterial based products),• insect growth regulators (IGR), •conventional insecticides, •non-petroleum oils, and •monomolecular film agents.

Larvicide Modes of Action

The timing of larvicide application is dependent on the nature of the control agent.

IGRs – Insect Growth Regulators• mimic an essential insect hormone• upsets the physiological molting process and kills mosquitoes in the subsequent pupal stage

Monomolecular films• reduce the water surface tension• the larvae are unable to attach to the water surface• the larva is not able to obtain air

Bacterial toxins• must be ingested by the larvae• toxins are released by the mosquito gut pH• toxins damage the larval gut

9. Name the most common type of adulticide application conducted today.

Treatment of adult mosquitoes (adulticiding) is the most visible practice exercised by mosquito control operations.

This option is usually reserved for managing mosquito populations that have reached the adult stage in spite of efforts to intervene in the larval stage or when such treatments have not, or cannot, be conducted.

Adulticides are often applied as ultra‑low‑volume (ULV) sprays in which small amounts (3 fluid ounces or less per acre) of insecticide are dispersed either by truck-mounted equipment or from fixed‑wing or rotary aircraft.

Fundamentals of ULV• ULV droplets must drift through the habitat and impinge on flying mosquitoes in order to provide optimal control benefits

• These applications are typically programmed to occur between dusk and shortly after dawn, when most beneficial insects are resting

• These tiny droplets are unlikely to impinge on objects larger than mosquitoes because those larger objects' physical characteristics and size cause the droplets to drift around rather than deposit on them

• The use of the fine ULV droplets means that there are literally millions more droplets to impinge on mosquitoes than there would be if larger droplets were used

10. Explain why the calibration of adulticide machines is so critical.

Using the proper size range for the droplets makes it possible to increase control efficiency and decrease the risk of adverse impact to the environment and public health.

The primary reason a piece of equipment must be calibrated is to make sure it is operating in an effective manner and discharging insecticide in the correct amounts according to label recommendations of the particular insecticide.

11. Discuss the importance of insecticide resistance to a mosquito control operator.

• Individual differences in susceptibility exist within each species.• Individuals who are substantially less susceptible may be present, generally at low frequencies, in at least some insect populations. • In the presence of a insecticide, it is these substantially less susceptible individuals that survive and reproduce. • Hence the development of a portion of a population of insects that are increasingly tolerant to a specific type of insecticide. • Insect populations exposed to insecticides that have a similar mode of action for extended periods can be expected to develop resistance.

How to prevent this resistance is an important aspect of mosquito control today.

Insecticide resistance is defined by differences in susceptibility that arise among populations of the same species exposed to insecticides.

The risk of developing insecticide resistance in insect populations can be minimized by the use of Integrated Mosquito Management techniques.

These practices try to reduce the need for insecticide applications. In addition, it is prudent to rotate the type of insecticide, active ingredient and corresponding mode of action of the insecticides used against an insect population.

While this may necessitate the use of a more expensive product for some applications, the long term benefits of preserving susceptibility far outweigh any short term costs.

There are a limited number of insecticides registered for mosquito control.

12. List 3 larvicides and 3 adulticides.

http://www.epa.gov/opp00001/health/mosquitoes/control.htm

Microbial Larvicides:• Bti• Bacillus sphaericus

Methoprene - IGR

Temephos - OP

Monomolecular Films

Oils

Larvicides kill mosquito larvae. Larvicides include biological insecticides, such as the microbial larvicides Bacillus sphaericus and Bacillus thuringiensis israelensis. Larvicides include other pesticides, such as temephos, methoprene, oils, and monomolecular films. Larvicide treatment of breeding habitats help reduce the adult mosquito population in nearby areas.

Spinosad

Mosquito adulticides are applied as ultra-low volume (ULV) sprays. ULV sprayers dispense very fine aerosol droplets that stay aloft and kill flying mosquitoes on contact. ULV applications involve small quantities of pesticide active ingredient in relation to the size of the area treated, typically less than 3 ounces per acre, which minimizes exposure and risks to people and the environment.

Organophosphates•Naled•Malathion•Chlorpyrifos

Pyrethroids•Permethrin•Resmethrin•Sumithrin

Zenivex - non-ester pyrethroid