By Marcia Anderson
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.