I just read a news release on a planned gypsy moth treatment in BC. I've included parts of the release below, in between the dashed lines. With environmental awareness the highest it's probably ever been, aerial spray programs usually get people concerned about the pros and cons.
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The Ministry of Environment has approved aerial spraying for an isolated infestation of gypsy moth (Lymantria dispar) in Courtenay this spring.
The planned treatment consists of three aerial applications of Foray 48B between April 15 and June 30, 2007 to control the moth. Foray 48B contains Bacillus thuringiensis var. Kurstaki (Btk), a naturally occurring, soil-based organism that only impacts caterpillars that eat sprayed leaves. Btk is naturally present in urban, forest and agricultural soil around the province. It has been approved to control gypsy moth larvae since 1961.
Treatment dates are weather-dependent and will be advertised closer to the first application date. Each treatment application will be completed before 7:30 a.m. The Ministry of Forests and Range will advise of spray dates one week and 24 hours before spraying begins.
Large gypsy moth populations defoliated sections of forests and residential areas in Ontario and the eastern U.S. in recent years and pose a threat to the province’s forests, orchards and urban trees. The moths are unintentionally brought to B.C. on vehicles, trains and materials from affected areas in eastern North America on an ongoing basis. The presence of moths can pose a quarantine threat and in 1999 resulted in the U.S. threatening to refuse shipments of trees and plants from B.C.’s nurseries without additional certifications.
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According to wikipedia, Bt is included in specific insecticides under trade names such as Dipel and Thuricide. Because of their specificity, these pesticides are regarded as environmentally friendly, with little or no effect on humans, wildlife, pollinators, and most other beneficial insects.
It seems that Bacillus thuringiensis is really not a threat to anything but the moths. Carefully planned aerial spraying, especially on such a small scale as this, shouldn't pose any harm to people or animals. I remember living on campus at the University of BC in the early 90's, when some similar spray programs were going on over the Point Grey area. It was a bit unsettling hearing the planes flying overhead and knowing they were broadcast spraying, but knowing the science behind Bt helps. Much better than risking the spread of the gypsy moth to BC's orchards, city trees and forests. We've already seen what the mountain pine beetle has done to pine trees in urban and rural areas, and we don't need a repeat scenario with an insect that attacks other species of trees.
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