. Conditions d'insectes et de maladies aux États-Unis, de 1979 à 1983 : quoi d'autre est de plus en plus dans nos forêts ?. Les insectes forestiers des États-Unis ; les maladies et ravageurs des arbres United States ; plantes résistant aux maladies et aux ravageurs. 15 spongieuse. La figure 8. La photographie infrarouge altitude plus Mifflin County, PA. La défoliation spongieuse apparaît gris bleu ONU- forêts endommagées ; photographie ; rouge vif et de l'eau photographies noir. F-705632 insecticides biologiques ; et le coût augmenté d'insecti- cides chimiques contenant des huiles de pétrole. Le travail se poursuit sur le développement de souches plus efficace de B.t. et impro

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. Insect and disease conditions in the United States, 1979-83 : what else is growing in our forests?. Forest insects United States; Trees Diseases and pests United States; Plants Disease and pest resistance. Gypsy Moth 15. Figure 8. High- altitude infrared photography over Mifflin County, PA. Gypsy moth defoliation appears gray blue; un- damaged forests photograph bright red; and water photographs black. F-705632 biological insecticides; and the in- creased cost of chemical insecti- cides containing petroleum oils. Work continues on the develop- ment of more effective strains of B.t. and improved formulations of the nuclear polyhedrosis virus. Furthermore, the use of the in- secticide diflubenzuron, an insect growth regulator that interferes with the molting of the larvae, in- creased 17 percent from 1979 to 1983. Isolated infestations have been successfully eradicated. Disparlure, a synthetic sex pheromone used to prevent or disrupt mating, has been effective in eradicating low-level gypsy moth populations in several areas. Similar results have been achiev- ed using applications of insec- ticides in combination with disparlure-baited traps. Small isolated populations have also been eradicated by releasing sterilized male moths. Sterilized males mate with wild females, which then lay sterile eggs. Larvae never emerge from the sterile eggs. Outlook Undoubtedly, the gypsy moth will continue its spread south and west. Consequently, all the susceptible hardwood forests from Maine to Louisiana could become infested. We can only speculate on how rapidly the insect will spread and what impact it will have on the hardwood forests. In the generally infested areas, gypsy moth control will rely on insecticides for some time to come. Eventually, however, silvicultural practices to reduce the impact of the insect may offer an alternative to insecticides in high-value timber stands. In addi- tion, the technique of flooding an area with sterilized life stages of the moth may event

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