Coffee Grounds for Mosquito Control

August 2, 2009

RECYCLE BIODEGRADABLE coffee grounds and simultaneously knockdown mosquitoes vectoring dengue, yellow fever, West Nile virus, malaria and other diseases. Hermione Bicudo at Universidade Estadual Paulista in Sao Paulo, Brazil, has been working towards that goal since the early 1980s. Mosquito control alternatives are needed, as mosquitoes are rapid, prolific breeders that rapidly develop resistance to pyrethroid, organophosphate and other types of insecticides.

Bicudo’s lab began studying caffeine effects on Drosophila fruit flies in the early 1980s. Drosophila fruit flies are a model insect widely used from the early twentieth century to unravel the mysteries of inheritance and genetics. Caffeine has been used relatively safely for centuries, and is found in medicines, cosmetics and food and beverages like coffee, tea, guarana and chocolate. Used coffee grounds are a ubiquitous waste product in modern caffeinated societies.

A resurgence of yellow fever mosquito, Aedes aegypti, in Brazil prompted Bicudo’s lab to test whether deleterious caffeine effects on Drosophila fruit flies (e.g. less frequent mating, less egg laying capacity, shorter life spans) might also slow mosquito population growth. Approximately four full soup spoons of used coffee grounds in a 250 mL glass of water killed 100% of aquatic mosquito larvae. This translated into fewer adult mosquitoes (the biting, blood-sucking stage) and less new mosquito egg laying (thus, lower mosquito populations over time). Used coffee grounds also have fertilizer value for plants, and can be dusted onto Bromeliads and other garden plants (possibly also puddles, ponds, tree holes, used tire breeding sites, etc.) where accumulated water forms potential mosquito breeding sites.

In contrast to other researchers, Bicuda’s lab found that caffeine solutions became more effective against mosquitoes with age. Day-old caffeine solutions took 20 days to kill 100% of mosquito larave; 25-day old caffeine solutions killed 100% of mosquito larvae in 1 day. Combined with elimination of mosquito breeding sites, used coffee grounds or caffeine solutions could prove very useful in IPM (integrated pest management) programs to slow pesticide resistance and reduce mosquito breeding.


Beating the Bed Bug Blues

July 15, 2009

“SUCH BUGS and goblins in my life,” said Shakespeare’s Hamlet during the medieval era when “bug” meant bed bug. Indeed, bedbugs have been part of the human condition from prehistoric times. By 400 B.C. the ancient Greeks were scratching bedbug bites and singing the Big Bed Bug Blues. Bat caves, bird nests and animal barns are the natural habitats supporting bed bugs and their goblin-like natural enemies like itch mites, assassin bugs, assorted ants, centipedes, and spiders.

Though bedbug biocontrol by the currently-known crop of natural enemies seems better left to the Batcave and more rustic outdoorsy habitats, natural ecological principles still apply in human dwellings. Contrary to the DDT-nostalgia (interestingly, lacking scientific citations) infesting Wikipedia, pesticides cannot substitute for human smarts in fighting bedbugs. Even in the heyday of DDT bed bugs were hard to kill and there was pesticide resistance, Clemson University urban entomologist Eric Benson told an Entomological Society of America (ESA) annual meeting. Indeed, overdoing pesticides is likely to kill natural enemies and stimulate outbreaks of new indoor pests (e.g. rat mites).

An integrated pest management (IPM) approach pits human ingenuity and a multiplicity of tactics against bedbugs. Shripat Kamble of the University of Nebraska told an ESA annual meeting of traditional bedbug remedies rememebered from a childhood in India: “People commonly used in the summertime heat treatment. Keeping the cot outside in the hot sun,” and shaking the bed so the bugs spilled onto bare ground hot enough to kill. “Another treatment that was commonly done was boiling water, and then pouring boiling water through all the hiding areas of the bed bugs…A lot of times it worked, and sometimes we still had problems.”

Nobody, not even the professionals, has a surefire remedy guaranteed to work against bedbugs every time in every household. Like Shakespeare and the ancient Greeks, bedbugs are likely to remain a part of the modern human condition.