The federal/state program to eradicate the light brown apple moth in California by spraying much of the Monterey Bay area puzzles some residents and concerns others. This large-scale attempt to disrupt the reproductive cycle pf the LBAM has inspired me to learn more about pheromones.

Let's start with the point where etymology meets entomology. The word "pheromone" was coined in 1959 by combining Greek words with the literal translation, "to carry that which sets in motion." A more poetic interpretation of this phrase yields, "the carrier of excitement."

A pheromone is "a substance that an animal gives off to trigger a specific behavior or developmental reaction in another member of the same species." This definition includes synthetic versions of natural substances. Both are fragrances that the intended recipient (an insect in this case) can detect even at very low concentrations and at very great distances, and may be either undetectable by, or meaningless to, other insects.

Scientists have produced synthetic pheromones that more than 1,600 insects use to attract mates or for a wide range of other purposes. Chemically speaking, the active ingredient in a pheromone may be a primary alcohol, hydrocarbons, epoxides, acetates or aldehydes. The synthetic sexual attractant pheromone for the light brown apple moth, Check Mate OLR-F, has two active ingredients that are acetates with long names that only a biochemist could love.

Spraying in Monterey County|

The plan of the California Department of Food and Agriculture for Monterey County includes two or more aerial sprayings of Check Mate OLR-F, which affects the male light brown apple moth in the same way as the natural substance produced by females of the species.

By giving the male moths a super-abundance of this sexual attractant, the spraying program confuses them and interferes with their ability to locate the females for mating or even an opportunity to get to know them over a casual luncheon of your favorite plants.

The spraying program targets areas where the insect pest has been spotted, and is designed as the first stage of more extensive spraying in Santa Cruz County, where a great many more light brown apple moths have been observed. The strategy resembles that used in controlling forest fires: start by controlling the perimeter of the problem, then work toward the center.

California's Department of Pesticide Regulation (DPR) has reported that, "the proposed applications (of Check Mate OLR-F) can be performed with minimal risk to the environment and public health" and concluded that there is no need for environmental monitoring.

The DPR notes that workers "directly involved in the application of the pheromone" would have the greatest potential exposure to the substance, but protective equipment (eye protection, gloves, long-sleeved shirt, long pants, etc.) would provide appropriate protection. The DPR also states, "Given the very low toxicity and extremely low application rates, no such protection is necessary for the general public ... any risk to the public would be considered insignificant."

The DPR's report cites an Environmental Protection Agency fact sheet on lepidopteran (i.e., moth) pheromones, which states "no risk to human health is expected from the use of these pheromones" and observes that, "during more than 10 years of use of lepidopteran pheromones, no adverse effects have been reported ..."

In my opinion, these scientific statements are credible and persuasive, even in a time when we might respond to political statements with a measure of skepticism.

The upside of pheromones|

Let us move beyond concerns over the possible downside of this spraying program, and consider its upside. We can immediately applaud the program because it replaces the previous spraying of nursery plants with the chemical pesticide chlorpyrifos, which is an organophospate. This is a highly toxic substance with product names such as Dursban Pro, Malathion and Diazinon.

The EPA has ordered the use of Dursban phased out in the United States because of environmental concerns for the safety of mammals and marine animals. Currently, its use is limited to very specific commercial applications.

The California Certified Organic Farmers has supported the CDFA's pheromone spraying program.

The CCOF, founded in 1973, calls itself "one of the nation's oldest and largest third-party organic certifying agencies." CCOF Executive Director Peggy Miars said, "The state is being extremely careful to choose nontoxic materials and to minimize spraying to key areas. We feel that the state is respecting the needs of organic farms as well as the concerns of citizens."

Another reason to support the pheromone spraying is its greater effectiveness in limiting the potential damage of the LBAM. Pesticides can be effective when they are applied directly to the pest, but the LBAM obviously could be appear in more places than could be treated safely with a powerfully toxic chemical. A benign pheromone, on the other hand, could be used to treat a large target area with confidence about public safety, environmental protection and cost-effectiveness.

The bottom line|

Those who have opposed this spraying program presumably are concerned with issues other than the scientific and economic justifications for controlling the LBAM with pheromones. They have presented two points: federal and state agricultural agencies have not given local citizens and public officials research data to prove that pheromones are safe for humans or a role in the decision-making process.

Such arguments reflect a distrust of federal and state authorities more than substantial concerns. To be realistic, we are exposed daily to numerous chemicals that have not been proven safe for human exposure, and federal and state agencies make countless decisions without citizen participation. Our complex, fast-moving society simply could not function if we require absolute foreknowledge of the consequences of our actions and decision-making at the grass roots level.

Assuming that the LBAM is a real threat to California's

$31 billion agricultural businesses, thoughtful people should prefer widespread spraying with pheromone to narrowly focused spraying with chlorpyrifos.

All things considered, this spraying program looks like a winner. While it might not eradiate the LBAM completely, it represents the best available strategy for controlling this particular pest.

More about pheromones |

My initial study of pheromones has uncovered a rich trove of gardening information. Look for more about the many ways that insects use pheromones and how humans are learning more about this form of insect communication. And you thought that soil microbes were fascinating!

Tom Karwin is a Santa Cruz resident and a member of the Monterey Bay Master Gardeners. He can be reached at gardening@karwin.com.