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Pupal weights and fecundities of spruce budworm from Minnesota had different means, coefficients of variation, and frequency distributions than spruce budworm from New Hampshire. The two variables were correlated in one of the populations but not the other.

Spruce budworm moths collected as larvae from two species of host trees in four populations were mated in single pairs in two years. In 1980 but not 1981, more of the intra-population matings than the inter-population matings were fertile. Host tree origin was not a significant factor in the level of sterility.

Caged field studies indicate that the foliage of western larch is apparently less suitable to western spruce budworm larval development than the foliage of Douglas-fir, subalpine fir, and Engelmann spruce.

The utilization of stored lipids (fat) for energy metabolism appears to be a fundamental process for many biological systems especially during the early stages of their development. The participation of the glyoxylate cycle (GOG) together with other metabolic sequences like gluconeogenesis and beta oxidation are necessary for the conversion of lipids to carbohydrates. This report describes the distribution of the GOG amongst biological systems and examines its importance to the development and existence of biological cells under different physiological conditions. The report also describes...

Western spruce budworm were reared on three host foliages and artificial medium. Trace element analyses showed large differences in elemental concentrations between food sources and only minor differences between insect life stages. Discriminant analyses were carried out to test the distinctiveness of adult chemoprints from each rearing regime. Fe, Cu, and Zn were distributed differentially between egg mass and other parts of the female moths. Females reared on artificial medium weighed more than foliage-fed females.

The epicuticular waxes from four host plants of the eastern spruce budworm are examined with respect to their influence on the feeding behavior of the sixth-instar larva. Both current and one-year old needles contain stimulating chemicals in their epicuticular wax layer. Some pure fatty acids known to occur in balsam fir wax are stimulatory, and may serve to enhance the already strong feeding response to sucrose.

Extracts of non-host plants and selected naturally occurring compounds have been screened for their effects on feeding by spruce budworm larvae, (Choristoneura fumiferana (Clem.), using as diet a filter paper substrate impregnated with the synergistic feeding stimulants, sucrose, and L-proline. The most potent feeding deterrents identified to date are alkaloids.

Female larvae ate about 1.5 times as much foliage as male larvae. Larvae ate significantly less old foliage than current foliage. Balsam fir current foliage was eaten in greater quantitities than any other foliage; white spruce current and balsam fir old were eaten to the same extent; very little old white spruce was eaten.

Feeding efficiencies and growth rates of western spruce budworm larvae varied among hosts tested. Pupae attained normal size regardless of host species. Candidate defensive compounds (tannins and phenols) varied only slightly with the vigor of the host. The relationship between these defensive compounds and measures of larvae growth were not entirely consistent with current theories on the role of secondary plant compounds.

Ample evidence exists that inland populations of Douglas-fir suffer varying amounts of defoliation by western spruce budworm (Johnson and Denton 1975; Williams 1967; McDonald 1981). Such variation in plant insect association can be the result of the plant escaping attack in time and place to actual confrontation between plant and insect (Harris 1980). Co-evolved genetic interaction between insect and plant is usually involved in initiation and preservation of plant polymorphisms, whether they be morphological or chemical responses (Gilbert 1982; Berenbaum 1983).