West Nile Virus

New Jersey Fights Mosquito Populations with Help from Tiny Crustaceans

By Marcia Anderson

Tiny copepods can decrease the need for pesticides

Tiny copepods can decrease the need for pesticides

Most people generally do not realize the number of areas around their own homes where mosquitoes can find stagnant water to lay their eggs. If something can hold water for more than a few days, it is a mosquito breeding habitat. If standing water can’t be eliminated, the control of mosquito larvae within the water container is the next best step. Some states have re-introduced natural predators, such as copepods, as part of a smart, sensible and sustainable approach called Integrated Pest Management (IPM), in the battle against mosquitoes and mosquito-borne diseases.

What are Copepods? Cousins of shrimp, copepods are tiny crustaceans that are usually less than 2.5 mm – the size of a pin head. They are used successfully to control mosquito larvae in Vietnam, Honduras, Brazil, Australia, Florida, Louisiana, New Jersey and Puerto Rico. Many large species of copepods are voracious predators of mosquito larvae. They are an environmentally friendly tool that provides more effective biological control than any other predatory invertebrate. They can actually lessen the need for pesticides.

Raising Copepods Copepods are being grown in large numbers in New Jersey and Louisiana. They are especially effective in small containers or pools of water found in garbage dumps, roadside ditches or piles of building rubble. They are also effective in controlling the Asian tiger mosquito, Aedes albopictus, which can breed in the smallest of places containing water.

Large copepod species thrive in clean containers especially if given a few grains of rice as an initial food supply. If they have devoured all of the mosquito larvae in a container, a few grains of rice will keep them happy and prevent starvation. Copepods survive longer in containers near trees or other vegetation because shade prevents the containers from drying and leaf-fall provides food and a reservoir for moisture.

Mass Distribution of Copepods Thousands of large copepods (Mesocyclops sp.) can be transported in a small container to sites where they are poured, ladled or sprayed into containers. They can also be transported in backpack tanks from which they are squirted into containers with a hand-held wand. Each tank can hold enough copepods to treat a thousand or more containers, ditches, debris storage areas or even rice paddies.

New Jersey is the first state in the Northeast to use copepods. Beginning in 2011, New Jersey began deploying native copepods to county mosquito control agencies, inspired by an extremely successful program in New Orleans, Louisiana. As of 2013, more than half of New Jersey counties had incorporated copepods in their mosquito management programs.

In New Jersey and Louisiana, state and county mosquito control workers release copepods into residential and commercial areas, naturally reducing the numbers of mosquitoes. There are 13,000 species of copepods but, according to professors at Florida State University’s Medical Entomology Lab, not all copepods are effective at controlling mosquitoes. They should be used only if they occur naturally in an area where they can be reproduced and counted on to reliably attack that area’s mosquito larvae. Native copepods exist in every state. Once the species are identified, it takes time to determine which are best for a laboratory breeding program. It takes at least six months to raise enough of them, more than 50,000, to begin deployment in large-scale mosquito control programs.

Much like the mosquito-eating fish used by most states, copepods are used in pools of standing water that are either hard to reach or are in areas too sensitive for pesticides. They’re more a preventive measure than an ultimate weapon, say New Jersey state officials, but they make a difference in narrowing the scale of the mosquito fight. They actually reduce the number of inspections that county workers have to make and reduce the amount of pesticides needed to control mosquitoes. Remember that when considering the introduction of any vertebrate or invertebrate species, local regulations must be followed and care must be taken not to introduce non-native species into natural aquatic environments.

By using the smart, sensible and sustainable steps IPM offers, you can take control of mosquitoes in your own community. First, eliminate breeding habitats with sanitation and maintenance. For areas of standing water that cannot be eliminated, native biological controls can be employed to facilitate a reduction of mosquitoes, resulting in a reduction of mosquito borne diseases and a diminished reliance on pesticides.

For more information on mosquito control in New York City go to:www.nyc.gov/html/doh/html/environmental/wnv-community.shtml. In other areas, contact your state cooperative extension agent or local health department for region-specific guidance and visit www2.epa.gov/mosquitocontrol.

About the Author: Marcia is with EPA’s Center of Expertise for School IPM in Dallas, Texas. She holds a PhD in Environmental Management from Montclair State University along with degrees in Biology, Environmental Design, Landscape Architecture, and Instruction and Curriculum. Marcia was formerly with the EPA Region 2 Pesticides Program and has been a professor of Earth and Environmental Studies, Geology, and Oceanography at several universities.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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West Nile Virus and Reduction of Mosquito Habitats – Part 1

By Marcia Anderson

I have been following the “Worst Outbreak of West Nile Virus (WNV) since 1999” reports in newspapers and on the Internet for days. So far there are 1,118 reported cases and 41 deaths.  Companies have been hired to spray insecticide by plane over Dallas, Texas since August 16. The pyrethroid insecticide selected is said to kill adult mosquitoes by direct contact. In addition, New York City began ground-based spraying on August 24, also to protect people from West Nile Virus. However, spraying is only a temporary answer to the problem, as only adult mosquitoes are killed. Mosquito larvae still reside in bodies of water and will emerge as adults one to five days later.

Why is mosquito control important? About 1 percent of the people that contract WNV usually get either meningitis, an inflammation of the spinal cord, or encephalitis, an inflammation of the brain. People with suppressed immune systems and older people are the most vulnerable to contracting the disease and there is no human vaccine for WNV.

Hungry mosquitoes are attracted to body warmth and exhalation of carbon dioxide. They also find their victims by sight and by chemical sensors. They are especially attuned to ammonia and lactic acid typical in human sweat. The sensors work best in humid air. Only the female mosquitoes require a blood meal which is necessary for making eggs. Did you know that women are bitten more often than men, as women have slightly higher body temperature than men?

What can you do to protect yourself? Follow the 4 Ds:

  1. Use an insect repellant for deterrent.
  2. Dress wearing long sleeves and long pants.
  3. Avoid being in mosquito prone areas around dusk and dawn.
  4. Make sure all standing water is drained.

The fact is that all mosquitoes need water to breed. Many mosquitoes living in urban and suburban settings prefer to breed in standing water rich in decomposing organic material and will not lay eggs in clear water. Dead leaves, grass clippings and algae, quickly begin to break down in moist habitats and produce an infusion that is highly attractive to the females. They are particularly abundant in areas where sewage leaks into drainage systems, catch basins and storm drains. Others will only lay eggs in clean water. The peak time some mosquitoes to bite is just following sunset and just before sunrise, so cover-up or use repellants if you are going to be outside at these times, however, there are some mosquitoes that are 24- hour feeders.

What else can you do? The best  non-chemical mosquito management approach is to reduce/eliminate breeding habitats through the following steps:

1. Identify locations and sizes of all stagnant water bodies, including basins, storm drains, blocked roof gutters, and all water retaining containers. These are all important mosquito larval habitats.

2. Remove or destroy domestic breeding sites. By eliminating all standing water and water collecting containers, you can reduce the number of mosquitoes in your neighborhood. Sites include discarded appliances, car parts, plastic bags, tarps, food containers, tires, pet water bowls left out for days,  saucers, potted plants, and birdbaths, kiddy pools, children’s play equipment left outside to collect water, and garbage cans and dumpsters without proper drainage or lids.

If you live in an area with swales, open stormwater culverts or trenches, they need to be maintained to prevent them from becoming filled with sediment and plant debris. This will cause ponding or puddles of water that may soon become a mosquito breeding habitat. Clogged gutters and flat roof tops with poor drainage are commonly overlooked mosquito breeding habitats.  Thus, if there is standing water close to you, that you cannot do anything about, please call 311 in New York City.

About the Author: Marcia is the bed bug and vector management specialist for the Pesticides Program in Edison. She has a BS in Biology from Monmouth, second degree in Environmental Design-Landscape Architecture from Rutgers, Masters in Instruction and Curriculum from Kean, and is a PhD in Environmental Management candidate from Montclair – specializing in Integrated Pest Management and Environmental Communications. Prior to EPA, and concurrently, she has been a professor of Earth and Environmental Studies, Geology and Oceanography at Kean University for 14 years.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.