Douglas-fir Cone Research Articles

Douglas-fir cone gall midges respond to shape and infrared wavelength attributes of host tree branches

AbstractWe tested the hypothesis that the conophagous Douglas-fir cone gall midge,Contarinia oregonensisFoote (Diptera: Cecidomyiidae), responds to infrared (IR) radiation and other electromagnetic wavelengths associated with cones of Douglas-fir,Pseudotsuga menziesii(Mirbel) Franco (Pinaceae). Early-season (March–April) thermographic images showed that cone orientation (upright, horizontal, pendant) and cone colour (green, purple, green/purple) did not affect apparent cone temperature (inferred from thermographic images). Tree components significantly differed in apparent temperature with foliage being coolest and branches warmest. There was no significant difference in the number of larvae in cones of different colours, and adult midges were equally attracted to traps painted green or purple, suggesting that cone colour does not affect oviposition decisions by gravid females. Adult midges were more strongly attracted to warm traps with IR frequency emissions higher than the background than to cold traps with IR frequency emissions lower than the background. They were also more strongly attracted to warm branch-shaped traps than to warm can-shaped traps. Collectively, these data indicate that the shape and IR attributes of Douglas-fir branches may serve as foraging cues forC. oregonensis.

Potential for pheromone-baited traps to predict seed loss caused by Contarinia oregonensis (Diptera: Cecidomyiidae)

AbstractIn seed orchards of Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco (Pinaceae), located in Washington State and Oregon, United States, we tested whether catches of male Douglas-fir cone gall midges, Contarinia oregonensis Foote, in pheromone-baited traps can be used to predict the extent of galled scales (= seed loss at harvest) caused by developing larvae. In 2000, 27 experimental blocks (4–7 ha each) were selected. In each block we recorded mean numbers of (i) male C. oregonensis captured in 20 pheromone-baited Wing traps, (ii) egg-infested scales in up to 50 conelets in early spring, and (iii) galled scales in up to 50 cones in late summer. In 2001, the experiment was repeated with 20 Delta traps in each of 26 experimental blocks. Moreover, catches of C. oregonensis and nontarget insects in Delta traps and Wing traps were compared in one additional orchard block in 2001. In both years there were positive correlations between mean numbers of egg-infested and galled scales and between mean numbers of captured male C. oregonensis and mean numbers of both egg-infested and galled scales, particularly when only experimental blocks with ≥50% of trees bearing at least 5 conelets were considered. Our results suggest that 4 or 2 captured male C. oregonensis in Wing or Delta traps, respectively, warrant insecticidal control of C. oregonensis. Delta traps, which captured fewer nontarget insects, would be more suitable than Wing traps for operational implementation of this technology.

(Z,Z)-4,7-tridecadien-(S)-2-yl acetate: sex pheromone of Douglas-fir cone gall midge, Contarinia oregonensis.

Our objectives were to identify and field test the sex pheromone of female Douglas-fir cone gall midge, Contarinia oregonensis (Diptera: Ce-cidomyiidae). Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract revealed a single compound (A) that elicited responses from male antennae. Hydrogenation of pheromone extract, followed by renewed GC-EAD analysis, revealed a new EAD-active compound with chromatographic characteristics identical to those of tridecan-2-yl acetate on five fused silica columns (DB-5, DB-210, DB-23, SP-1000, and Cyclodex-B). Syntheses, chromatography, and retention index calculations of all possible tridecen-2-yl acetates suggested that the candidate pheromone A was a tridecadien-2-yl acetate with nonconjugated double bonds. Synthetic candidate pheromone component (Z,Z)-4,7-tridecadien-2-yl acetate (Z4Z7) cochromatographed with A on all analytical columns and elicited comparable antennal activity. In GC-EAD analyses that separated the enantiomers (Z,Z)-4,7-tridecadien-(S)-2-yl acetate (2S-Z4Z7) and (Z,Z)-4,7-tridecadien-(R)-2-yl acetate (2R-Z4Z7) with baseline resolution, only 2S-Z4Z7 as a component in a racemic standard or in pheromone extract elicited antennal responses. In Douglas-fir seed orchards, sticky traps baited with 2S-Z4Z7 captured male C. oregonensis, whereas 2R-Z4Z7 was behaviorally benign. Comparable catches of males in traps baited with racemic Z4Z7 (50 microg) or virgin female C. oregonensis suggested that synthetic pheromone baits could be developed for monitoring C. oregonensis populations in commercial Douglas-fir seed orchards.

Attributes of Red Squirrel Caches in a Non-Serotinous Conifer Forest

Factors influencing caching behavior of red squirrels (Tamiasciurus hudsonicus) were studied in Pattee Canyon, Lolo National Forest, Montana. Tamiasciurus hudsonicus in this population cache ponderosa pine (Pinus ponderosa) cones and Douglas-fir (Pseudotsuga menziesii) cones in multiple caches of varying size. In comparison with randomly-selected, potential cache sites, caches were associated with soft soil and were near T. hudsonicus nests. Frequency of cache use was not significantly correlated with any measured attribute of caches. The use of multiple caches in this population may be a response to feeding on non-serotinous cones, which must be cached quickly.

Cone and Seed Insect Phrenology in a Douglas-Fir Seed Orchard During Three Years in Western Oregon

Seasonal patterns of cone and seed insect activity and seed loss relative to cone production and weather patterns were examined over a 3-yr period in a Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco, seed orchard in western Oregon. Six insect species showed distinct patterns of occurrence and cone or seed damage during this period. A weevil, Lepesoma lecontei (Casey); the Douglas-fir cone gall midge, Contarinia oregonensis Foote; and two lepidopterans, Barbara colfaxiana Kearfott and Dioryctria abietivorella (Grote), damaged cones or seed exposed during late April each year. The Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl, damaged seed in cones exposed during May and June; western conifer seed bug, Leptoglossus occidentalis Heidemann, was most damaging in cones exposed July-August.

Response of Douglas-Fir Cone and Seed Insects to Implants of Systemic Insecticides in a Northern California Forest and a Southern Oregon Seed Orchard

The systemic insecticides acephate, dimethoate, and carbofuran were implanted into Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco, at Oakridge, OR, and Willow Creek, CA, to evaluate their effectiveness in reducing seed and cone insect damage. The acephate-implant treatment significantly reduced seed damage by the Douglas-fir cone moth, Barbara colfaxiana (Kearfott) (Lepidoptera: Olethreutidae), and a cone gall midge, Contarinia oregonensis Foote (Diptera: Cecidomyiidae), and significantly increased the percentage of filled seed by 300% at the California site. Neither dimethoate nor carbofuran significantly affected any of the seed or cone insects encountered in this study. Acephate was not effective against a seed chalcid, Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), nor the western conifer-seed bug, Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae). The association observed between C. oregonensis damage and undeveloped seeds suggests that management strategies that include effective control measures should also include methods to monitor and reduce seed abortion.

Aerial Applications of Esfenvalerate to Suppress Contarinia oregonensis (Diptera: Cecidomyiidae) and Megastigmus spermotrophus (Hymenoptera: Torymidae) in Douglas-Fir Seed Orchards

Aerial applications of esfenvalerate significantly reduced populations of a Douglas-fir cone gall midge, Contarinia oregonensis Foote, and a Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl, in mature Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, seed orchards. Populations of the spruce spider mite, Oligonychus ununguis (Jacobi), increased significantly in treated areas. Our results demonstrated that aerial applications can be made under conditions in the Pacific Northwest and can reduce insect damage levels with between 10 to 20 times less metric insecticide than when high-volume orchard sprayers are used.

DISTRIBUTION OF BARBARA COLFAXIANA (KEARFOTT) (LEPIDOPTERA: TORTRICIDAE) EGGS WITHIN AND AMONG DOUGLAS-FIR CROWNS AND METHODS FOR ESTIMATING EGG DENSITIES

AbstractThe spatial and frequency distributions of Douglas-fir cone moth, Barbara colfaxiana (Kearfott), eggs in Douglas-fir trees and stands were determined by dissecting 13 262 conelets collected from 81 trees in three sites and 2 years. There were no consistent trends in egg density associated with crown level or aspect. The frequency distribution of eggs per conelet fitted the negative binomial in three of five site-years but a common k for the negative binomial could not be calculated. Green’s index of aggregation suggested that the cone moth egg distribution was significantly aggregated in each site-year.The optimal number of conelets per tree to sample was determined to be four in forest stands and three in seed orchards. The number of sample trees required for estimating mean egg density with 10% and 20% precision and 90% confidence was calculated for a range of mean egg densities using the method of Kuno. The sample sizes required to estimate a control threshold density of 0.6 eggs per conelet with 10% precision and 90% confidence were very large and would be impractical for operational use. Therefore, a sequential sampling plan was developed for use in seed orchards that would classify cone moth egg densities as either above or below a critical density at which 10% seed loss would be expected.

Influence of Host Genotype on Douglas-Fir Seed Losses to Contarinia oregonensis (Diptera: Cecidomyiidae) and Megastigmus spermotrophus (Hymenoptera: Torymidae) in Western Oregon

Seed losses to the Douglas-fir cone gall midge, Contarinia oregonensis Foote, and Douglas-fir seed chalcid, Megastigmus spermotrophus (Wachtl), were measured in a Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco, clonal seed orchard and in a Douglas-fir progeny plantation in western Oregon. Seed losses to both insects differed significantly (P < 0.05) among clones and among the progeny of selected parental crosses. Seed loss differed more than three times between least-infested and most-infested clones or progeny. Seed losses in the progeny plantation indicated that resistance to these two insects is a heritable trait, with greater resistance showing a tendency to dominate over lesser resistance. Insect responses to host genotype may be modified by factors associated with the position of the tree within the stand. Implications of these results for tree improvement programs and seed orchard management are discussed.

Trunk-Implanted Acephate to Protect Douglas-Fir Seed Crops on Individual Trees in Northern California

To reduce seed and cone insect damage, 0.875 g per capsule of acephate (technical grade) was implanted into individual Douglas-fir, Pseudotsuga menziesii (Mirb.) Franko, trees on 15 April or 6 May 1985. A spacing of one capsule per 10 cm of trunk circumference was used. Neither implant treatment affected actual infestation levels of a Douglas-fir cone gall midge, Contarinia oregonensis Foote, or a Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl. Both implant treatments, however, significantly reduced the damage of a fir coneworm, Dioryctria abietivorella (Grote), and the Douglas-fir cone moth, Barhara colfaxiana (Kearfott), by at least 62%. The latter implant significantly increased the number of filled seeds per cone by 154% compared with control trees, but the difference between implant treatment dates was not significant. Interspecific interaction between reduction of damage by Lepidoptera and the increase in C. oregonensis-damaged seeds and filled seeds suggests a negative association with reduced predation.

LACINIPOLIA PATALIS GROTE (LEPIDOPTERA: NOCTUIDAE) INFESTING DOUGLAS-FIR CONES: A NEW HOST RECORD

Larvae of Lacinipolia patalis (Grote) (Lepidoptera: Noctuidae) were discovered in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) cones collected from the Louisiana-Pacific Corporation's Little River Seed Orchard near Trinidad Head in Humboldt County, CA (elevation 91 m) during the fall of 1985. Previous surveys have not reported this noctuid from Douglas-fir cones (Keen 1958; Tietz 1972; Furniss and Carolin 1977; Hedlin et al. 1980; Ruth 1980; Schowalter et al. 1985). Its usual hosts are blackberry and loganberry (Rubus spp.) and roses (Rosa spp.); it normally feeds on foliage and, to some extent, dead fruit bases and dead leaves (Crumb 1956). The shift from angiosperm leaves and fruit to gymnosperm cones is somewhat surprising. Blackberries, however, grow around the perimeter of the seed orchard and along the rows between trees, and so provide an abundance of the usual host for L. patalis nearby.

Inventory Monitoring for Estimating Impact of Insects on Seed Production in a Douglas-Fir Seed Orchard in Western Oregon

Impact of various factors on seed production was examined in a Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) seed orchard in western Oregon during 1984. Cones were examined monthly between April and September for mortality or evidence of insect damage. Loss of immature cones began early in the growing season and had a substantial impact on seed production. A newly discovered cone-feeding weevil, Lepesoma lecontei (Casey), caused a large proportion of this mortality. Unexplained cone mortality (possibly frost damage), undeveloped seed, Douglas-fir cone gall midge ( Contarinia oregonensis Foote), and Douglas-fir seed chalcid ( Megastigmus spermotrophus (Wachtl)) were other major causes of seed loss. Crown elevation was important for an accurate estimate of the importance of some seed-loss factors. An inventory monitoring system for Douglas-fir seed production based on early monitoring of immature cones, identifying specific seed loss factors, stratified crown sampling, and an adequate sample size, is suggested.

In vivo pupal response to orientation detected by proton magnetic resonance chemical microscopy

1. 1. Proton magnetic resonance ( 1H-NMR) spectra revealed immediate and reversible changes in overwintering Douglas-fir cone moth ( Barbara colfaxiana) pupae when the whole animal was inverted. 2. 2. Principal compounds observed by this technique were aqueous fluids and lipids. 3. 3. Changes were seen in the distribution of aqueous fluids within pupae and in the resonant frequencies of portions of both the aqueous fluid and lipid protons. 4. 4. Proton distribution maps showed that haemolymph collected at the lower extremity of the animal. 5. 5. Portions of the aqueous fluid in the haemolymph pool were observed to be different from each other. 6. 6. Water signals of haemolymph associated with the thorax showed greatest changes in 1H-NMR chemical shift when pupae were inverted. 7. 7. Changes in distribution of haemolymph appear to be due to gravitational force and activity of the heart. 8. 8. Observed in 1H-NMR chemical shift changes of portions of the haemolymph may be due to alterations of the effective magnetic field arising from anisotropic magnetic susceptibilty, the biological activity of organs and organ systems, or a combination of both.

Single and Double Application of Fenvalerate and Dimethoate for Control of Douglas-fir Seed and Cone Insects1

Douglas-fir cones were sprayed once (13 April) or twice (13 April and 16 May) with a 0.025% concentration of fenvalerate or a 0.23% concentration of dimethoate to reduce infestation of seed and cone insects. Single application of either chemical did not significantly reduce incidence of fused seed caused by a Douglas-fir cone gall midge, Contarinia oregonensis Foote. The double application of fenvalerate significantly reduced (64%) the infestation of a Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl. Two applications of dimethoate significantly reduced infestation levels of both the cone gall midge and the seed chalcid by 78 and 39%, respectively. The increase in percentage of extractable filled seeds associated with all spray treatments was higher than that of the unsprayed control, but the difference was not significant.

DISTRIBUTION OF CONTARINIA OREGONENSIS FOOTE (DIPTERA: CECIDOMYIIDAE) EGGS IN DOUGLAS-FIR SEED ORCHARDS AND A METHOD OF ESTIMATING EGG DENSITY

AbstractEfficient sampling procedures for estimating densities of eggs of Douglas-fir cone gall midge (DFCGM), Contarinia oregonensis Foote, on individual trees as well as for orchards were developed from data collected in Douglas-fir seed orchards in 1978–1981. Egg distribution was contagious and generally fitted the negative binomial distribution on individual trees, but a common k could not be estimated. Tree and crown level affected density of midge eggs within orchards. Average density at the midpoint of the cone-bearing portion of the crown was not significantly different from the tree average. The optimum sampling pattern in an orchard, i.e. one conelet from the midpoint of the cone-bearing portion of each of 120 trees, would require 120 person-hours to process the samples when DFCGM egg densities are high (worst-case situation).

DAMAGE PREDICTION FOR CONTARINIA OREGONENSIS FOOTE (DIPTERA: CECIDOMYIIDAE) IN DOUGLAS-FIR SEED ORCHARDS

AbstractDamage at cone harvest by the Douglas-fir cone gall midge, Contarinia oregonensis Foote, was positively correlated with the number of egg-infested scales per conelet in the spring. Reducing the average number of galled seeds per cone by 1.5 increased the average number of filled seeds per cone by 1.0 in insecticide trials. Optimum sample sizes for estimating average densities of egg-infested scales were calculated to be one conelet per tree and 150 trees per orchard. The mean crowding variable was linearly related to average density so a sequential sampling technique relative to a critical density, using Iwao’s procedure, was developed for determining the need of control actions.

EVALUATION OF FOUR CHEMICAL INSECTICIDES REGISTERED FOR CONTROL OF THE DOUGLAS-FIR CONE GALL MIDGE, CONTARINIA OREGONENSIS (DIPTERA: CECIDOMYIIDAE), AND THE DOUGLAS-FIR SEED CHALCID, MEGASTIGMUS SPERMOTROPHUS (HYMENOPTERA: TORYMIDAE), IN DOUGLAS-FIR SEED ORCHARDS

AbstractOxydemeton-methyl, azinphosmethyl, dimethoate, and acephate were evaluated in Douglas-fir seed orchards for control of Douglas-fir cone gall midge, Contarinia oregonensis Foote, and Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl. Results varied with infestation levels and specific chemicals. There was no significant reduction of infestation levels of either insect with the application of acephate. Oxydemeton-methyl injections, oxydemeton-methyl spray, and dimethoate significantly reduced cone gall midge damage. All four chemicals were ineffective against the seed chalcid for infestations of less than 10% of extractable seed. Oxydemeton-methyl injections, azinphosmethyl, and dimethoate significantly reduced the incidence of seed chalcid when the infestation was high (61%). There was no statistically significant difference (α = 0.05) for pairwise comparisons between chemicals which significantly reduced the infestation levels of either insect.

EFFECT OF TEMPERATURE DURING MAY TO AUGUST ON TERMINATION OF PROLONGED DIAPAUSE IN THE DOUGLAS-FIR CONE MOTH (LEPIDOPTERA: TORTRICIDAE)

The Douglas-fir cone moth, Barbara coljaxiana (Kearfott) (Lepidoptera: Tortricidae), has the capacity for prolonged diapause, i.e. diapause for two or more winters (Hedlin 1960). This diapause allows for temporal spacing of populations and reduction of intraspecific competition. Specifically, when cone crops are small, excessive moth densities can occur and cause conelet mortality prior to completion of feeding by cone moth larvae, which results in moth mortality. If all moths emerged each year, moth-caused destruction of the conelet population, particularly in years of light production, would have drastic effects on the moth population.

CHANGES IN HEMOLYMPH PROTEINS IN RELATION TO DORMANCY OFBARBARA COLFAXIANAKFT. AND THE INFLUENCE OF ECDYSONE AND PRECOCENE ON THE PROTEIN COMPOSITION

AbstractHemolymph proteins of the Douglas-fir cone moth,Barbara colfaxiana(Kft.), in the year of pupation (year P) and the next year (year P + 1) were studied by visual examination and analysis of digitized images of isoelectric focussing patterns. Differences in these proteins between light and dark individuals in year P and P + 1 were not related to dormancy duration but reflected the extent of pharate-adult development. Hormone applications were more effective in changing hemolymph proteins of light insects than those of dark ones. Changes in the hemolymph proteins of light insects in year P + 1 were not very obvious by visual examination of gels but were readily detectable by digital image analysis and showed that development occurred in these insects through June-September leading to visible pigmentation differences observable in relation to dormancy commitments of these insects.

CONE AND SEED INSECTS IN DOUGLAS-FIR,PSEUDOTSUGA MENZIESII(MIRB.) FRANCO, SEED ORCHARDS IN THE WESTERN UNITED STATES: DISTRIBUTION AND RELATIVE IMPACT

AbstractDouglas-fir cones were collected from 17 seed orchards in California, Oregon, and Washington in the fall of 1983. Cones were completely dissected and seed losses ascribed to the Douglas-fir cone gall midge (Contarinia oregonensis(Foote)), the Douglas-fir seed chalcid (Megastigmus spermotrophus(Wachtl)), the Douglas-fir cone moth (Barbara colfaxiana(Kearfott)), and the fir coneworm (Dioryctria abietivorella(Groté)). There appear to be great differences between orchards, but overallC. oregonensisandM. spermotrophuscollectively destroyed approximately 70% of the filled seed. Physiographic province significantly (P&lt;0.05) explained variation in damage by all insect species between seed orchards. In general, damage by all species increased from northern provinces to southern mountainous provinces. Damage byC. oregonensisandB. colfaxianaappeared to be related to land use or management factors, as well.