Lake Concerns

Biology and Control of Aquatic Plant
A Best Management Practices Handbook: Third Edition
Lyn A. Gettys, William T. Haller and David G. Petty, editors

“Aquatic plants do have the potential to create mosquito habitat, as they do slow flow and create more quiescent areas suitable as mosquito habitat.” -Dr.Brett Hartis

Chapter 5: Aquatic Plants, Mosquitoes and Public Health, page 31
James Cuda, University of Florida

This chapter talks about mosquitoes and Public Health. Below is part of Chapter 5. Please notice the yellow and pink highlighted text.

My interpretation is mosquitoes ARE A SERIOUS threat with these weeds, and the milfoil concentrations are putting the health and safety of property owners and their families in jeopardy without a doubt!

Chapter 5: Aquatic Plants, Mosquitoes and Public Health

Approximately 200 species of aquatic plants are classified as weeds in North America and nearly 50, or 25%, are considered to be of major importance. Aquatic plants become weedy or invasive when they exhibit rapid growth and produce dense monocultures that displace more desirable native plants, reduce biodiversity, interfere with flood control, impede navigation and create breeding sites for disease-vectoring mosquitoes.

The role of aquatic plants in mosquito outbreaks
The aquatic stages of most mosquitoes are not adapted to life in moving waters. They require quiet pools and protected areas where they can obtain oxygen at the water surface via a single air tube (or siphon) in the larval stage or two tubes (or horns) in the pupal stage. Aquatic weed infestations create ideal habitats for mosquito development because the extensive mats produced by many weeds reduce the rippling effect of the water surface. Some mosquito species even have a modified air tube that they insert into the roots of aquatic plants to obtain oxygen. This protects them from light oils that are applied to the water surface for mosquito control.

From a mosquito control perspective, there are two major larval habitat categories that are of concern to aquatic plant managers: standing water (permanent and temporary) and flood water (detention and retention areas). Permanent water mosquitoes (e.g., species in the genera Anopheles , Culex , Coquillettidia and Mansonia) are associated with aquatic plants in freshwater marshes, lakes, ponds, springs and swamps. Temporary water mosquitoes (e.g., species in the genera Culiseta , Ochlerotatus [= Aedes ] and Psorophora ) are associated with vegetation in saline or brackish ditches, borrow pits and canals and freshwater drainage ditches which alternate between wet and dry based on water use and rainfall events.

Permanent water
The amount and type of vegetation occurring in a permanent water body is a good indicator of its potential to produce mosquitoes. For example, the presence of floating mats of cattails, torpedograss, alligatorweed or para grass suggest that larvae of permanent water mosquitoes are likely to be present. Also, dense stands of aquatic plants create ideal conditions for mosquito development by restricting water flow in drainage and irrigation ditches.

The association between aquatic plants and certain species of mosquitoes has evolved over millions of years. The uncontrolled growth of invasive plants often provides an undisturbed habitat that mosquitoes prefer and where they can proliferate. Mosquitoes can colonize virtually any type of water body and aquatic vegetation provides a perfect environment for mosquitoes to thrive. Management of dense surface-growing exotic and native aquatic plants in permanent and temporary water systems is critical to reduce the habitats suitable for mosquito development. After all, “…Without aquatic plants, most of our freshwater mosquito problems would not exist…” (Wilson 1981).

Mosquitoes are insects that belong to the family Culicidae in the order Diptera, or true flies. They are similar in appearance to other flies except they have fragile bodies and their immature stages (eggs, larvae and pupae) develop entirely in aquatic environments. These insects are serious pests that have plagued civilizations throughout human history. In addition to their annoying and often painful bites, they transmit some of the world’s most devastating diseases – dengue, encephalitis, yellow fever, dog heartworm and the dreaded malaria. According to a recent report from the University of Florida, more than 500 million new cases of malaria are reported worldwide each year, resulting in about 1 million deaths. Most of the deaths that are caused by malaria are in children under 10 years of age. The importance of mosquitoes from a nuisance and public health perspective cannot be overstated.