by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications
Abstract
The southern pine beetle, Dendroctonus frontalis Zimmerman (SPB), and eight of its hymenopterous parasites were studied to evaluate the effects of SPB density and tree bark thickness (BKTH) on the parasites.
Significant differences between infestations were found for densities of Dendrosoter sulcatus Muesebeck (Braconidae), Heydenia unica Cook and Davis (Pteromalidae), Rhopalicus sp. (Pteromalidae), Roptrocerus xylophagorum (Ratzeburg) (Torymidae), and SPB. Roptrocerus xylophagorum and SPB varied similarly among infestations. Parasite and SPB densities were generally highest at midbole of infested trees and decreased toward the ends. The male-to-female ratio for Roptrocerus xylophagorum was 1.7 to I, this being the only parasite observed to depart from a I:I sex ratio.
Rhopalicus sp. density increased linearly with SPB density and decreasing BKTH. Roptrocerus xylophagorum density was linearly related to SPB density and BKTH, and an SPB density-BKTH interaction was found. Spathius pallidus Ashmead (Braconidae) density was not related to SPB density but increased quadratically with decreasing BKTH. Coeloides pissodis (Ashmead) (Braconidae) and Cecidostiba dendroctoni Ashmead (Pteromalidae) displayed inverse density-dependent responses to SPB density, and linear responses to BKTH. Dendrosoter sulcatus, H. unica, and Eurytoma spp. (Eurytomidae) exhibited inverse density dependent responses to spa density, and quadratic responses to BKTH.
To read the full article please visit the link below:
GARGIULLO, PM, and CW BERISFORD. 1981. “EFFECTS OF HOST DENSITY AND BARK THICKNESS ON THE DENSITIES OF PARASITES OF THE SOUTHERN PINE-BEETLE (COLEOPTERA, SCOLYTIDAE).” Environmental Entomology10 (3): 392–99.
https://doi.org/10.1093/ee/10.3.392.
by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications
Abstract
This laboratory study investigates the effects of constant temperature on reemergence of the southern pine beetle, Dendroctonus frontalis Zimmermann. Beetles reemerged at temperatures between 12.5 and 33.3°C, with the relationship of adult residence time and constant temperature forming a backwards “J” -shaped curve. Adult residence time was greatest at 12.5°C (46 days) and least at 27°C (12 days). The distributions of those limes changed with temperature. At 12.5 and 15°C, the distributions were near uniform, but as temperature increased to 30°C, the distributions became peaked and skewed right. Above 30°C, the distributions became less peaked. About 90% of the beetles reemerged at temperatures between 12.5 and 30°C, whereas above 30°C the percentage dropped precipitously. Males reemerged I or 2 days before females at temperatures below 30°C, but the reverse condition was found at 30°C or above. A two-component model is used to predict reemergence as a function of temperature. The first component describes reemergence rates as a function of temperature. The second component distributes the reemerging population over physiological time. When combined, these components distribute reemergence over calendar time, and are suitable for incorporation into a larger population model of D. frontalis.
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GAGNE, JA, TL WAGNER, PJH SHARPE, RN COULSON, and WS FARGO. 1982. “REEMERGENCE OF DENDROCTONUS-FRONTALIS (COLEOPTERA, SCOLYTIDAE) AT CONSTANT TEMPERATURES.” Environmental Entomology11 (6): 1216–22.
https://doi.org/10.1093/ee/11.6.1216.
by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications
Abstract
Two estimators of trends in Dendroctonus frontalis Zimmerman populations are evaluated. One estimator is brood increase ratio, R*, the brood beetles emerging per parent. The other is within-tree survival, S*, the brood beetles emerging per egg. The sampling distributions
of R* and S* were studied using computer simulations. Both R* and S* are biased, always overestimating R and S, but S* is less biased and more consistent than R*. The distributions of R* and S* become less biased and more peaked as sample size increases.
The validity and sensitivity of tests of hypotheses based on R* and S* are discussed. Because the distributions of R* and S* are not normal, the estimators should be used cautiously in tests of hypotheses that assume normality. Besides the statistical problems inherent in using R* and S*, there are problems in gathering sufficient data to calculate the estimators reliably. Complete dissection of bark samples and precise timing of sampling are vital.
To read the full article please visit the link below:
GAGNE, JA, TL WAGNER, PE PULLEY, JD COVER, and RN COULSON. 1981. “AN ANALYSIS OF ESTIMATORS OF TRENDS IN SOUTHERN PINE-BEETLE DENDROCTONUS-FRONTALIS ZIMMERMAN (COLEOPTERA, SCOLYTIDAE) POPULATIONS.” Environmental Entomology10 (1): 31–38.
https://doi.org/10.1093/ee/10.1.31.
by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications
Abstract
Dispersal behavior of the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae), in response to synthetic aggregating pheromone (frontalin) indicates an exponential decrease in response with distance from the site of emergence. Differential response during dispersal among genotypes at a polymorphic esterase locus was found by using starch gel electrophoresis. These differences produced allelic distributions that predict increased genetic diversity concurrent with increasing dispersal distance from the source population.
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FLORENCE, LZ, PC JOHNSON, and JE COSTER. 1982. “BEHAVIORAL AND GENETIC DIVERSITY DURING DISPERSAL -ANALYSIS OF A POLYMORPHIC ESTERASE LOCUS IN SOUTHERN PINE-BEETLE, DENDROCTONUS-FRONTALIS (COLEOPTERA, SCOLYTIDAE).” Environmental Entomology11 (5): 1014–18.
https://doi.org/10.1093/ee/11.5.1014.
by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications
Abstract
Interactions during colonization among the southern pine bark beetle guild members Dendroctonus frontalis Zimmermann, Ips avulsus (Eichhoff), and Ips calligraphus (Germar) were investigated in nine loblolly pines, Pinus taeda L. This study examined host colonization and the manner by which competition is reduced among members of a guild. Two components of colonization were used for this analysis: accumulation of attacking adults and gallery construction. Attack and gallery construction were examined in individual trees and as an average process for all trees. Vertical arrangements of D. frontalis attack and gallery were similar among trees, but the arrangement differed for each Ips species. I. avulsus showed the most rapid accumulation of attacking adults and gallery followed by D. frontalis and I. calligraphus. D. frontalis and I. calligraphus produced less gallery per adult at high adult densities, suggesting presence of a density-dependent compensatory feedback mechanism that regulates their egg densities. I. avulsus did not show this relationship. The species studied are members of a guild that is partially maintained through reduction or avoidance of competition. We found that differences in attributes of attack patterns among guild members served to separate breeding areas and, therefore, reduce competition for oviposition sites among the species. The density-dependent compensatory feedback mechanism reduced competition within and among brood species.
Keywords
Pinus taeda, Scolytidae, colonization, insect ecology, cohabitation, competition
To read the full article please visit the link below:
FLAMM, RO, TL WAGNER, SP COOK, PE PULLEY, RN COULSON, and TM MCARDLE. 1987. “HOST COLONIZATION BY COHABITING DENDROCTONUS-FRONTALIS, IPS-AVULSUS, AND .1. CALLIGRAPHUS (COLEOPTERA, SCOLYTIDAE).” Environmental Entomology16 (2): 390–99.
https://doi.org/10.1093/ee/16.2.390.
