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Title: Effects of aerially applied mexacarbate on western spruce budworm larvae and their parasites in Montana
Author: Williams, Carroll B., Jr.; Shea, Patrick J.; McGregor, Mark D.
Source: Res. Paper PSW-RP-144. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 14 p
Station ID: RP-PSW-144
Description: In tests on the Bitterroot National Forest, Montana, in 1965 and 1966, mexacarbate, aerially applied at the rate of 0.15 lb a.i./gal/acre (68.04 g a.iJ3.785 1/0.404 ha), killed about 90 percent of the western spruce budworm (Choristoneura occidentalis Freeman) populations. More parasitized budworm larvae survived treatments than nonparasitized. Apanteles fumiferanae Viereck and Glypta fumiferanae Viereck-two overwintering parasites-and Phaeogenes hariolus (Cresson), Mesochorus sp., and tachinids-late larval, pupal parasites-increased following treatments. But parasites tended to return to pretreatment levels the next year. In 1968, mexacarbate, aerially applied at the rate of 1 oz a.i./pt/acre (28.35 g a.iJ473.16 m1/0.404 ha), achieved 71 percent mortality in one area and 53 percent in another. A. fumiferanae, G. fumiferanae, and tachinids increased in the area of lowest budworm mortality, and parasitism by A. fumiferanae and G. fumiferanae remained significantly higher than the 1968 prespray level for from 1 to 2 years, respectively. The results suggest that mexacarbate may be used to moderately suppress populations of budworm larvae in order to increase the ratio of parasites to budworm.
Key Words: insecticides; mexacarbate; naled; Choristoneura occidentalis; Apanteles fumiferanae; Glypta fumiferanae; Phaeogenes hariolus; Mesochorus; tachinids.
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Williams, Carroll B., Jr.; Shea, Patrick J.; McGregor, Mark D. 1979. Effects of aerially applied mexacarbate on western spruce budworm larvae and their parasites in Montana Res. Paper PSW-RP-144. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station; 14 p.
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