Effects of two juvenile hormone analogs on hemolymph and fat-body metabolites of the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)

Abstract

Early sixth instar larvae of Choristoneura fumiferana were treated with LD50 doses of the juvenile hormone analogs fenoxycarb and methoprene. Fenoxycarb caused an initial decrease, then an increase, in hemolymph carbohydrate concentration; fat-body glycogen was depleted initially, then increased in concentration (cf. controls) toward the end of the 6-day experimental period. Methoprene caused an opposite effect on hemolymph carbohydrates, but a similar effect (cf. fenoxycarb) on fat-body glycogen. Protein concentrations in the hemolymph of fenoxycarb-treated and methoprene-treated insects were lower than those of controls. The concentration of fat-body soluble protein of fenoxycarb-treated insects was initially lower, then higher, than that of controls. Methoprene did not alter soluble protein levels in the fat bodies. Lipids in the hemolymph of fenoxycarb-treated insects were depleted (cf. controls) throughout the experimental period; in the fat bodies, lipid concentration was elevated initially, then lowered. In methoprene-treated insects, hemolymph lipid levels were similar to those of controls up to 96 h post-treatment, then declined to lower than control levels; fat-body lipid content was initially higher, then lower, and finally higher, than that of controls. Fenoxycarb and methoprene caused severe, yet dissimilar, disruptions in metabolism of all three nutrients.