Tests for induction of feeding preferences in larvae of eastern spruce budworm using extracts from three host plants

Feeding preferences to extracts from three host plants were determined for sixth-instar eastern spruce budworm larvae reared on one of three hosts or on artificial diet. Preferences of foliage-reared larvae were compared to those of diet-reared, or naive, larvae. No effect of plant induction was found using amino acids and bases and chloroform extracts on test disks in three-choice experiments. Possible effects of habituation for sugars and glycosides from white spruce were shown. Organic acids contributed to a phenomenon of avoidance learning in larvae reared on all three hosts, showing that this fraction from balsam fir was the least deterrent, while that from black spruce was the most deterrent.     

Enniatins fromFusarium avenaceum isolated from balsam fir foliage and their toxicity to spruce budworm larvae,Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae)

Material extracted from hyphae ofFusarium avenaceum, isolated from foliage of balsam fir,Abies balsamea, was toxic to spruce budworm larvae when incorporated into insect diet. The major insecticidal component of the toxic fraction was identified by chemical and spectroscopic methods as enniatin complex, rich in enniatin A/A₁. Possible ecological implications of these observations are considered.     

Orientation behavior of second-instar larvae of eastern spruce budwormChoristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae) in a y-type olfactometer

A two-choice, wind-tunnel olfactometer was designed and contructed to determine whether second-instar eastern spruce budworm larvae,Christoneura fumiferana (Clem.), could detect and discriminate among host-plant volatiles. Volatiles of current year's growth ofPicea glauca were preferred over those ofP. rubens, P. mariana, or air.Abies balsamea was preferred overP. mariana or air.P. rubens andP. mariana were both preferred over air. Two-year-old growth ofP. glauca, A. balsamea, P. rubens, andP. mariana were all preferred over air. Current year's growth of these host evergreen species was usually preferred over former year's growth of the same species in each case.     

Behavioral responses of the female eastern spruce budwormChoristoneura fumiferana (Lepidoptera,Tortricidae) to the sex pheromone of her own species

Female eastern spruce budworm moths respond to the synthetic sex pheromone of their own species (a mixture ofcis- andtrans-11-tetradecenal) by walking, antennal grooming, flexation of the body, extension of the ovipositors, and oviposition. The sex pheromone is perceived by receptors on the antennae. Electroantennogram responses from the female are approximately two-thirds the amplitude of those obtained from males.     

Olfactory response of eastern spruce budworm larvae to red spruce needles exposed to acid rain and elevated levels of ozone

Second-instar eastern spruce budworm larvae,Choristoneura fumiferana (Clem.), were tested in a two-choice, Y-type, wind-tunnel olfactometer for preferences for red spruce,Picea rubens Sarg., needles exposed for eight weeks to charcoal-filtered air (CFA) or 0.15 ppm ozone (O₃) in combination with acidified rainfall at pH 4.2 or 3.0. Volatiles from needles treated with CFA plus pH 4.2 rain (control) were preferred over those from needles exposed to pH 3.0 rain + O₃ or O₃ alone; O₃-treated needles were chosen over those exposed to pH 3.0 rain + O₃. No preference was shown between the pH 4.2 and 3.0 rain treatments. Larvae chose purified air flowing through the olfactometer in preference to needle volatiles from the pH 3.0 rain + O₃ treatment.The use of trade, firm, or corporation names in this paper is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture or the Forest Service of any product or service to the exclusion of others that may be suitable.     

Behavioral effects of secondary components of sex pheromone of western spruce budworm (Choristoneura occidentalis) free

In a laboratory wind tunnel, upwind flight and close-range orientation to a pheromone source by maleC. occidentalis were facilitated by the addition of the secondary componentsE/Z11-tetradecen-1-ol acetate (8911) andE/Z11-tetradecen-1-ol (8515) to low source concentrations of the primary components,E/Z11-tetradecenal (928). Male responses to the blends tested never equalled their responses to virgin females. The primary components alone, when released at a rate similar to that of a calling female, never elicited male upwind flight or source location. However, the addition of the secondary components enhanced these behavioral sequences.Lepidoptera: Tortricidae.     

Feeding responses of eastern spruce budworm larvae to sucrose and other carbohydrates

Spruce budworm larvae reared on an artificial diet were tested for preference of twelve carbohydrates over a water control. A strong preference for sucrose was seen, followed by fructose, inositol, and glucose. Male and female larvae do not differ in their responses to sucrose. The behavioral threshold for sucrose is at 10^–4 to 10^–3 M, with a peak response in the range of 0.01 to 0.05 M sucrose. Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae).Work leading to this publication was funded in part by a USDA Forest Service sponsored program entitled Canada/United States Spruce Budworms Program (grant 23–352), and in part by the National Sciences and Engineering Council of Canada (operating grant A9723), and in part by the Whitehall Foundation.     

Effect of foliage proximity on attraction ofChoristoneura occidentalis andC. retiniana (Lepidoptera: Tortricidae) to pheromone sources

Pheromone-baited traps located close to both host and nonhost crowns were more attractive than traps located between crowns for bothC. occidentalis Freeman andC. retiniana (Walsingham) at both 10 m and at 1.5 m above the ground. At 10 m height, traps located in host foliage were more attractive than those located in nonhost foliage, but at 1.5m height there was no significant difference. These results were obtained for both dense and sparse populations ofC. occidentalis and sparse populations ofC. retiniana. We conclude that the tree species on which a virgin female is located is not an important factor restricting mating between closely relatedChoristoneura spp. Also, the tree species on which a trap is located may not be an important factor that must be standardized in developing pheromone monitoring systems forC. occidentalis andC. retiniana.     

Chemistry and field evaluation of the sex pheromone of western spruce budworm,Choristoneura occidentalis,Freeman

Chemical analyses and field bioassays showed a mixture of 92% (E)- and 8% (Z)-11-tetradecenal to be the sex attractant pheromone of the western spruce budworm,Choristoneura occidentalis Freeman. Females were also found to emit small amounts of the corresponding acetates and alcohols, but these components were not active in the bioassay. In contrast, in whole female tip extracts, (E)-11-tetradecenyl acetate predominates, and aldehyde pheromone components are present in lesser quantities, suggesting that final biosynthesis of pheromone takes place just prior to or during emission. At release rates approximating that of the female (2–4 ng/hr), a 928EZ blend of the synthetic aldehydes was at least as attractive as live females. Addition of the corresponding acetates or alcohols up to 50% of the aldehyde content did not significantly enhance or inhibit attraction. No major differences were apparent in pheromone production of females from a laboratory stock or from field collections from diverse geographic locations ranging from Colorado to British Columbia.     

Feeding preferences of eastern spruce budworm larvae in two-choice tests with extracts of mature foliage and with pure amino acids

The feeding preferences and feeding rates of eastern spruce budworm on extracts from mature foliage normally avoided by larvae indicate that the chemical composition of four major host plants does not account for this avoidance. Other factors such as the degree of lignification and/or moisture content of the older foliage may play a more important role. Of 14 amino acids tested, alanine, lysine, proline, and serine stimulated feeding. The interactions of amino acids and sucrose were studied, and the results are discussed in relation to feeding preferences and feeding rates.     

Sex pheromone chemistry of the western spruce budwormChoristoneura occidentalis Free

SCOT capillary Chromatographic and SCOT capillary chromatographic-mass spectrometic analyses of gland washes and effluvia of virgin femaleChoristoneura occidentalis Free, have been conducted with both a diapausing and nondiapausing strain of this insect. The following compounds were identified in gland washes and effluvia in both strains:E andZ11–14Ald,E andZ11–14Ac,E andZ11–14OH and 14Ald, 14Ac, and 14OH. The average aldehyde: acetate: alcohol ratio found by analysis of single glands by virgin females (nondiapausing strain) was 170.73. Analysis of virgin female effluvia gave this ratio as 1038 (diapausing strain: %Z=8, 11, 15, respectively) and 1036 (nondiapausing strain: %Z=8, 11, 12, respectively). The saturated components were generally 1–2% of theE isomer in each case. Comparisons of EAG responses of bothC. occidentalis andC. fumiferana toE11–14Ald,E11–14Ac andE11–14OH were made. Correlations with both laboratory and field data previously published were also made betweenC. fumiferana andC. occidentalis.Lepidoptera: Tortricidae.     

Behavior and survival of western spruce budworm,Choristoneura occidentalis Freeman,exposed to an ω-fluorinated pheromone analogue

-Fluorinated (E)-11-tetradecenal (14F-E11-14: Al) was synthesized using 1,10-decanediol as a starting compound. Male and female western spruce budworm,Choristoneura occidentalis Freeman, moths exposed to 14F-E11-14: Al had LC₅₀s (CI) of 12.0 (7.4–19.5) µg and 41.7 (22.7–76.2) µg, respectively. Antennectomized moths had lower mortality rates than normal moths. 14F-E11-14:Al elicited slightly lower amplitudes than 97:3 (E/Z)-11-tetradecenal (E/Z11-14:Al) in electroantennogram studies, but the lag or recovery period following excitation by 14F-E11-14:Al was much lower than forE/Z11-14:Al at the same concentrations. 14F-E11-14:Al andE11-14:Al evoked similar responses from male moths in wind-tunnel evaluations but neither compound was as effective as a virgin female in stimulating moths to fly upwind to contact the lure.     

The role of monoterpenes in resistance of Douglas fir to western spruce budworm defoliation

We conducted defoliation experiments with 7- to 8-year-old clones of Douglas fir [Pseudotsuga menziesii (Mirb.) Franco var. glauca] to assess the role of monoterpenes as a resistance mechanism to western spruce budworm (Choristoneura occidentalis Freeman) defoliation. The grafted clones were derived from mature trees that showed resistance or susceptibility to budworm defoliation in the forest. All clones were exposed to either budworm defoliation or nondefoliation treatments in 1998 and 1999 under greenhouse conditions. We found that the total concentration of monoterpenes in current-year foliage varied greatly between two consecutive years in clones in the greenhouse and in their corresponding mature trees in the forest. Fractional composition of different monoterpenes was similar between different years and between clones and mature trees, indicating genetic control of this trait. Two different defoliation experiments were conducted to assess the importance of budburst phenology as a factor determining host plant resistance. In the 1998 experiment, budworm feeding was matched to the budburst of each individual plant. Monoterpene concentration was high in 1998, and budworm potential fitness was greater on clones from the resistant mature trees that had lower concentrations of total monoterpenes. In the 1999 experiment, budworm feeding was matched to budburst of the whole population of plants in order to mimic conditions similar to insects feeding on trees in the field. The concentration of monoterpenes was low in 1999, and budworm fitness was not related to monoterpenes. Total monoterpene concentration was negatively related to foliar nitrogen concentration, suggesting that C/N balance may affect monoterpene synthesis in needles. However, tree growth was not related to total monoterpene concentration. We concluded that expression of differences in budworm resistance among Douglas fir genotypes might be caused by interactions among multiple resistance mechanisms such as needle monoterpenes and tree budburst phenology.     

Rate of release of spruce budworm pheromone from virgin females and synthetic lures

The rate of pheromone [(E)- and (Z)-11-tetradecenal] release from calling virginChoristoneura fumiferana females and synthetic lures was determined in both static and aerated atmospheres. In a static system ca. 2 ng/hr was recovered per female. Owing to the > 75% adsorption onto the females' bodies in static atmospheres, the actual release rate has to be corrected to roughly 9–27 ng/hr, depending on the percentage adsorbed. In the air-flow system, females were found to release between 4 and 20 ng/hr. On a 168 light-dark cycle, calling began 1–2 hr before lights-off and continued nonstop until lights-on. Pheromone was emitted throughout calling, while no pheromone was detected during the noncalling periods.Lepidoptera: Tortricidae.Published as Journal Article No. 10258 of the Michigan Agricultural Experiment Station.     

Feeding preferences of spruce budworm (Choristoneura fumiferana Clem.) larvae to some host-plant chemicals

Single-choice and three-choice tests were used to determine the relative importance of host-plant chemical extracts in eliciting feeding by spruce bud worm larvae. Water-soluble components of the host trees are the most important and, of these, the sugar and glycoside fractions are the most stimulating. The amino acid and organic base fractions have no apparent effect. The organic acid fractions deter feeding slightly.Lepidoptera: Tortricidae.Supported by the National Sciences and Engineering Research Council of Canada, Operating Grant No. A9723 to P.J.A.     

Spruce budworm (Choristoneura fumiferana) pheromone chemistry and behavioral responses to pheromone components and analogs

This paper reviews the sex pheromone chemistry and pheromone-mediated behavior of the spruce budworm and related coniferophagous (Choristoneura) budworms. InC. fumiferana, temporal changes in pheromone-gland monounsaturated fatty acids (pheromone precursors) enable the prediction of the primary sex pheromone components. This technique may also be applicable for predicting additional pheromone components. Tetradecanal (14 Ald), previously shown to enhance close-range precopulatory behavior, lowers the threshold of response by males for upwind flight to a pheromone-component source. Spruce budworm males maintain upwind flight to 955 (E/Z)-1,12-pentadecadiene (diolefin analog) after initiating upwind flight to a primary-component pheromone source (955E/Z11-14Ald). This is the first demonstration of apparently normal male flight responses to a pheromone analog.Lepidoptera: Tortricidae     

Role of Douglas fir (Pseudotsuga menziesii) carbohydrates in resistance to budworm (Choristoneura occidentalis)

The current year's growth of Douglas fir contains galactose, unusual in that this carbohydrate makes up 78.7% of the total carbohydrate fraction. An agar diet study was undertaken to determine the effects of galactose, other carbohydrates, and terpenes on western spruce budworm larval mortality, growth rate, and adult biomas production. All concentrations of the carbohydrates and terpenes tested, as well as other mineral elements not tested, were typical of the current year's foliage of Douglas fir. In experiment I, the diet containing 5.61% total carbohydrate did not significantly affect larval mortality when compared to the control diet. However, diets containing 9.45% and 15% total carbohydrate concentrations significantly increased larval mortality 64% and 96.1%, respectively, when compared to the control. Also in experiment I, terpenes alone (78.9% morality) and terpenes in combination with 9.45% and 15% total carbohydrates significantly increased larval mortality (97.2% and 100%, respectively) when compared to mortality on the control diet (44%). To determine which carbohydrate was causing the adverse effect, 6% glucose, 6% fructose, and 6% galactose were placed individually and in combination with terpenes in diets in experiment II. The 6% galactose diet significantly increased larval mortality and reduced growth rate when compared to the control, glucose, and fructose diets. Glucose resulted in 16% less larval mortality, significantly enhanced female larval growth rate and pupal weight, but did not affect male larval growth rate and pupal weight, when compared to the control. Fructose resulted in a significant decrease in larval mortality and a general trend of enhanced female and male larval growth rate and pupal weight. Larval mortality on terpenes alone was not significantly different from the control, but terpenes with 6% galactose increased larval mortality and decreased female and male growth rate and pupal weight significantly when compared to glucose-terpene and fructose-terpene diets. No significant interactions were found between carbohydrates and terpenes in either experiment.     

Some solid-phase syntheses of the sex attractant of the spruce budworm—trans-11-tetradecenal

The sex attractant of the spruce budworm,Choristoneura fumiferana,trans-11-tetradecenal (I), was synthesized on solid phases by three different routes from inexpensive 1,10-decanediol. The preparation of thetrans-alkene I directly on the polymer support was not completely stereoselective.The Use of Polymer Supports in Organic Synthesis, XIII.     

Attraction of male spruce budworm moths,Choristoneura fumiferana (Clemens), to pheromone-baited traps in small-tree thinnings

Mean catches of spruce budworm,Choristoneura fumiferana (Clemens), moths were not significantly different among four small-tree thinning treatments of young spruce-fir-hemlock regeneration. Significant inverse relationships were found between trap catches and distances to nearby spruce-fir-hemlock overstory. Prevailing wind directions indicated that moths were attracted anemotactically to upwind pheromone sources. No definite trends were detected between catches and temperature or precipitation.Lepidoptera: Tortricidae.A contribution to the Canada/ United States (CANUSA) Spruce Budworms Program. Mention of proprietary products does not constitute an endorsement of those products by the USDA.     

Roles of minor components in pheromone-mediated behavior of western spruce budworm male moths

The behavior of male western spruce budworm moths,Choristoneura occidentalis Freeman, was observed in a flight tunnel in response to virgin females and synthetic sex pheromone components, alone and in blends. Pheromone blends were also compared in the field using sticky trap bioassays. Pheromones were incorporated into small rods of polyvinyl chloride. The blend of 928 (E/Z)-11-tetradecenal-8911 (E/Z)-11-tetradecenyl acetate-8515 (E/Z)-11-tetradecenol (AldAcOH) that approximated that released from a virgin female moth elicited levels of response similar to those elicited by the female. This blend induced a significantly greater percentage of moths to fly upwind and land at the lure than did the Ald lure. In contrast to the flight-tunnel bioassays, the numbers of moths caught in Ald-baited sticky traps in the field were not significantly increased by the addition of Ac and OH lures. The net upwind groundspeed of flight in response to the 0.05% Ald lure was lower than that in response to the virgin females and was significantly increased by the addition of Ac + OH lures in two of three bioassays. The flight-tunnel bioassays support the hypothesis that the natural blend of major (Ald) and minor (Ac + OH) components stimulates the precopulatory behavior of western spruce budworm male moths at long range (> 1 m downwind) as well as at close range.