The April edition of Estuary magazine, a publication of the CalFed program and the San Francisco Public Utilities Commission, has some coverage of the “Moth Mess” as they call it. (CalFed is a joint California/Federal agency that conducts scientific research and makes decisions related to water use in the Sacramento River Delta — what’s causing the decline of the Delta Smelt, how much water do the salmon need, that sort of thing). For those of you who have been living in caves for the past few months, the issue is that the “Light Brown Apple Moth,” an Australian species, has established a foothold in California. The moth is potentially a major agricultural pest, and could also be a threat to some plants that are important to natural ecosystems, and California wants to do aerial spraying of pheromones over the entire state to disrupt the moth’s mating in an attempt to totally eradicate it before it becomes fully established. Some Bay Area cities have sued to prevent this.
The Estuary article says that (1) analysis shows that bird kills on Monterey Bay were not, as some people have claimed, due to the “checkmate” pheromone spray; (2) an oft-quoted report by UC Santa Cruz’s Daniel Harder, that says that the moth is not a major pest in New Zealand, has been criticized by New Zealand researchers who “issued a stinging rebuke to his paper’s conclusion”; and (3) the California Department of Food and Agriculture is claiming success in eliminating the moth from some areas in Southern California through use of the pheromone spray.
[UPDATE: Thursday, April 24: “Santa Cruz County Superior Court Judge Paul Burdick ruled Thursday morning that aerial spraying to control the light brown apple moth could not continue in Santa Cruz County” pending an environmental review, which the state is trying to avoid on the grounds of an “agricultural emergency.” The Santa Cruz Sentinel has an article about this, thanks to a blog commenter for passing this along.]
If it were my call, I would choose some alternative to spraying in the parts of the state that are objecting the most, and maybe in all densely populated areas, pending some more study about human health effects. But I think it’s a close call. Deciding to spray is not unreasonable. Suing to stop the spraying is also not unreasonable. Some of the public comments by opponents of spraying are unreasonable, though.
People dread risks that they’re not used to much more than risks of comparable magnitude that they are used to. (There are actually researchers who study this effect and try to quantify it in various ways). We breathe literally millions of 0.5- to 10-micron particles per day of pet dander, brake dust, pollen, toner, cigarette smoke, viruses, combustion products, etc., etc., many of which are chemically and/or biologically active, but we literally don’t even think about them, most of the time. But the prospect of adding something new to the mix is scary, even if it’s a tiny quantity that (unlike the above) you’ll only be exposed to for a very short time. There seems to be a lot less resistance to the idea in agricultural areas, where they’re used to the idea of much more toxic stuff being sprayed around all the time. I’m not saying that spraying toxic chemicals around is a good thing! In fact, a problem with _not_ spraying pheromones now is that if the moth gets established as an agricultural pest, the amount of pesticide use is likely to go up in the future, to control the moths.
I also think there’s a phenomenon like one I sometimes experience…bear with me for the analogy. When we’re leaving the house, my wife will sometimes say “did you lock the back door after going out this morning?” If she didn’t ask, I would be quite confident that it was fine, but once she asks it introduces this gnawing element of doubt. I always go back and check, and indeed, the door is always locked. (This also works in reverse, if I ask my wife she also can’t forget about it). Somehow, just bringing the question to the forefront seems to make it more likely that the answer is “no.” Similarly, just the fact that people have prominently raised the question of whether the spray is safe, seems to make it more likely that it isn’t. Or at least, I fancy that is an effect.
There are negatives to spraying pheromones, such as possible human health impacts, even severe ones for a few people. There are negatives to not spraying pheromones, including possible crop damage, ecosystem damage, and negative health and ecosystem impacts from future spraying of pesticides. It’s by no means obvious whether spraying pheromones now will have worse environmental impact in the long run than allowing the moth to spread (coupled with future chemical attempts to control it). It’s also by no means obvious which will have worse human health impacts in the long run. I wish everyone on both sides would stop pretending that the answer is obvious, and try to have a rational or at least calm discussion of it.
By the way, the California Department of Food and Agriculture (remember, they have an agenda too!) has a press release about the criticisms of Harder’s article.