Environmental Almanac: Pesticides should be small tool in management plan
In anticipation of the 31st Insect Fear Film Festival, which is Saturday at the University of Illinois, this week's column is written by two members of the Entomology Graduate Student Association: Michelle Duennes and Todd Johnson:
The theme of this year's Insect Fear Film Festival is "PESTICIDE FEAR!" In one of our two feature films, "Riders of the Whistling Pines," Dichlorodiphenyltrichloroethane (aka DDT) plays a prominent role. As the story opens, an outbreak of tussock moths is threatening the health of the trees in the North Woods. Government foresters want to spray DDT to eliminate the pests and keep the forest healthy.
Here's the plot twist: A bunch of greedy loggers want the trees to be damaged so they can cut and sell the wood.
Whereas 65 years ago pesticides were portrayed as heroes, today you would be hard-pressed to find anything in praise of them. As entomologists, we're concerned about the health of insects, but we also recognize that pesticides can be really useful.
Without them, many farmers simply would not be able to grow or sell crops damaged by insect pests. Take California, where almonds are king. More than 500,000 acres of orchards contribute about 80 percent of worldwide almond production.
A pest of almonds is the navel orangeworm. During its immature stage, the caterpillar feeds on the developing almond. Without effective control measures, this insect could severely damage the $4.3 billion industry.
That's where pesticides like pyrethroids come into play. Pyrethroids act on the nervous system of an insect, causing paralysis and death, and they're very effective against navel orangeworms.
There is a catch, though: Pesticides are great at what they do, but they should not be the major focus of an insect pest management program. (Entomologists generally favor a system known as Integrated Pest Management, which uses chemical, biological and cultural controls synergistically to control pests and reduce inputs of pesticides into the environment.)
The problem with pyrethroids is that they aren't very specific. In addition to killing the navel orangeworm, they also kill the honeybee pollinators of the crop, as well as beneficial predatory mites. Growers are now advised not to apply these pesticides right before or during flower bloom and avoid their use if possible.
Our second feature film emphasizes (in a sensationalized and exaggerated fashion) the tradeoffs to pesticide application.
"Locusts: The 8th Plague" is a 2005 Syfy original about a swarm of genetically engineered, flesh-eating locusts. When the locusts escape from a government research facility in Idaho, the military wants to eradicate them with chemical weapons.
Colt Denton, local entomologist, also wants to save the local human population. But instead of chemical weapons, he proposes using "organic pesticides." Here, the movie mixes things up a bit.
The characters use "organic" to mean nontoxic and safe for the environment. In reality, the term "organic insecticides" as used today refers to insecticides that are not synthesized in a laboratory. (In the 1940s and '50s, "organic insecticide" meant any pesticide synthesized in the laboratory that did not contain heavy metals such as copper and arsenic — those insecticides were called "inorganic.")
An example of an "organic" pesticide would be nicotine, a familiar toxin from tobacco plants that acts on the nervous systems of animals and can be very deadly at low doses. Synthetic analogues of nicotine, the neonicotinoids, have recently gained infamy because of their potential effects on honeybees; a severe mishap with a pesticide applied inappropriately in Oregon caused the mass death of more than 50,000 bumblebees.
To reduce their negative effects of pesticides, it's important to understand the biology of the target insect(s) and how they will affect the environmental as a whole. Additionally, pesticides should be used only when necessary, and in conjunction with other management tools.
We hope you learned a little bit about pesticides and will join us as we suspend our disbelief (briefly) and enjoy some great pesticide fear-related movies. For more information, visit life.illinois.edu/entomology/egsa/ifff.html or facebook.com/IFFFatUofI.
Environmental Almanac is a service of the UI School of Earth, Society and Environment, where Rob Kanter is communications coordinator. Environmental Almanac can be heard on WILL-AM 580 at 4:45 and 6:45 p.m. on Thursdays.