(Beyond Pesticides, June 9, 2014) A recent talk given by Donald Weston, PhD, a professor emeritus in UC Berkeley’s Department of Integrative Biology, to a community group in San Jose, California warned residents about the dangers that lawn care insecticides present to local aquatic life. The talk focused on the problems synthetic pyrethroids and fipronil can have on Hyalella azteca and Chironomus dilutes. Increasing levels of pesticide runoff in local stream systems have not only led to decreased populations of these aquatic crustaceans, but also populations that have become resistant to pesticides. Aquatic invertebrates are extremely sensitive to pesticide runoff and different states around the country have struggled with creating pesticide regulations that foster a healthy aquatic ecosystem. A good way to reduce pesticide runoff is to transition away from toxic land care methods and adopt organic practices.
Hyalella crustaceans, a tiny shrimp-like animal, are hypersensitive to pyrethroids, which are a class of insecticides used by professional lawn care companies and found in common products like Raid and mixed with fertilizer products like Scotts Turf Builder under the name SummerGuard. Chironomus dilutes, a red worm-like invertebrate, is sensitive to fipronil, which is used to kill fleas on dogs and cats and on lawns to control ants and termites. Currently, Contra County, California professional pest control operators use 13,300 pounds of pesticides, which do not include pesticides used by private citizens. Hyalella curstaceasn, which live in Contra County creeks, are exposed to such high levels of these chemicals that they have begun building resistance to pyrethroids.
Dr. Weston was quoted in a San Jose Mercury News article saying, “It scares us, because that tells us there’s enough pyrethroid in the creek to cause them to mutate. The sensitive pests have been killed off; the rest have mutated and survived.”
Previous studies performed by Dr. Weston have found pyrethroids at high levels in streams throughout California. Urban runoff data, taken between 2006 and 2010, showed all communities in the Sacramento area and the Bay Area had toxic levels, especially after a rainfall. Dr. Weston first began looking at pyrethroid levels in streams bordering farm fields in 2004, and reported levels in some creek sediments high enough to kill Hyalella curstaceasns, which are used by the U.S. Environmental Protection Agency (EPA) as an indicator of the health of freshwater sediment.
The streams have become so contaminated with pyrethroids that, according to Dr. Weston, “We’d have to flood the county 6,046 feet deep to dilute it enough so that Hyalella could live. That’s equal to two Mount Diablos, stacked on top of each other.”
Pyrethroids are synthetic versions of pyrethrin, a natural insecticide found in certain species of chrysanthemum. It initially was introduced on the market as a ”˜safer’ alternative to the highly toxic organophosphates, such as chlorpyrifos and diazinon which were banned for homeowner use in 2001 and 2004, respectively. They are now one of the most popular class of household pesticides, available in the form of powders and sprays to control ants, mosquitoes, fleas, flies, and cockroaches. Pyrethroids are dangerous to aquatic life even at concentrations used to eliminate mosquitoes. Of the varieties of pyrethroids used, befinthrin was most commonly found in previous research conducted by Dr. Weston.
Fipronil, a broad spectrum insecticide, was first introduced in the U.S. in 1996 and is highly toxic to aquatic life. and understood not to be readily biodegradable. In water and sediment that lack oxygen, fipronil degrades more slowly, with a half-life of 116-130 days and its breakdown products are also considered to be highly toxic to aquatic organisms. Beyond it being incredibly toxic to fresh water invertebrates, it is also highly toxic to bees.
Other states besides California have also struggled with the effects that pesticides can have on aquatic invertebrates. Last summer, Connecticut Governor Daniel Malloy signed into law House Bill 6441, which banned methoprene and resmethrin, a pyrethroid insecticide, in coastal areas such as the Long Island Sound because of declines in lobster populations. Declines in the Sound’s lobster population have been alarmingly common for the past 15 years, devastating fishermen and the local economy that depends on them. Connecticut legislators say that they were convinced that banning the two mosquito pesticides after learning that Rhode Island and Massachusetts had enacted similar bans with successful results. A similar bill to ban the use of methoprene was also introduced in Suffolk County, New York last summer.
One way to help change this problem is to start managing your lawn organically. For information on how to manage your lawn without the use of harmful pesticides, see Beyond Pesticides’ Lawns and Landscapes webpage. The site also provides an online training, Organic Land Care Basic Training for Municipal Officials and Transitioning Landscapers, to assist in going pesticide-free.
Source: San Jose Mercury News
All unattributed positions and opinions in this piece are those of Beyond Pesticides.