Parasitism Rates of Spruce Budworm Larvae: Testing the Enemy Hypothesis Along a Gradient of Forest Diversity Measured at Different Spatial Scales

Abstract Context Although the spatiotemporal dynamics of spruce budworm outbreaks have been intensively studied, forecasting outbreaks remains challenging. During outbreaks, budworm-linked warblers (Tennessee, Cape May, and bay-breasted warbler) show a strong positive response to increases in spruce budworm, but little is known about the relative timing of these responses. Objectives We hypothesized that these warblers could be used as sentinels of future defoliation of budworm host trees. We examined the timing and magnitude of the relationships between defoliation by spruce budworm and changes in the probability of presence of warblers to determine whether they responded to budworm infestation before local defoliation being observed by standard detection methods. Methods We modelled this relationship using large-scale point count surveys of songbirds and maps of cumulative time-lagged defoliation over multiple spatial scales (2–30 km radius around sampling points) in Quebec, Canada. Results All three warbler species responded positively to defoliation at each spatial scale considered, but the timing of their response differed. Maximum probability of presence of Tennessee and Cape May warbler coincided with observations of local defoliation, or provided a one year warning, making them of little use to guide early interventions. In contrast, the probability of presence of bay-breasted warbler consistently increased 3–4 years before defoliation was detectable. Conclusions Early detection is a critical step in the management of spruce budworm outbreaks and rapid increases in the probability of presence of bay-breasted warbler could be used to identify future epicenters and target ground-based local sampling of spruce budworm.

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Demography and spatial dynamics in balsam fir stands after a spruce budworm outbreak

Canadian Journal of Forest Research ◽

10.1139/x11-037 ◽

2011 ◽

Vol 41 (5) ◽

pp. 1112-1120 ◽

Cited By ~ 10

Author(s):

Sergio Rossi ◽

Hubert Morin

Keyword(s):

Choristoneura Fumiferana ◽

Spatial Scales ◽

Spatial Dynamics ◽

Abies Balsamea ◽

Spruce Budworm ◽

Balsam Fir ◽

Permanent Plots ◽

Random Pattern ◽

Advance Regeneration ◽

Competition For Resources

The renewal of balsam fir (Abies balsamea (L.) P. Mill.) stands is related to the recurrent spruce budworm (Archips fumiferana Clemens [syn.: Choristoneura fumiferana (Clemens)]) outbreaks that favour the growth of the regeneration following death of the dominant trees. The aim of this study was to investigate the population demography and the spatial relationships among individuals in four permanent plots of the boreal forest of Quebec, Canada, after a spruce budworm outbreak. This was realized by collecting data on trees and saplings every five years from 1994 to 2004 and by using Ripley’s K statistics. The younger plots showed recruitment of up to 90 new trees·ha–1·year–1, and mortality following competition among individuals affected up to 27% and 50% of the trees and saplings, respectively. In the plot with the lowest tree density, sapling recruitment was estimated as 378 new individuals·ha–1·year–1. Saplings were aggregated at all spatial scales, whereas trees showed a random pattern of stem distribution. A significant tendency to separation between saplings and trees was observed. The specific stand dynamics observed in balsam fir are connected to an abundant advance regeneration and an age-dependent competition for resources in a heterogeneous environment with different levels of resource availability.

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AVAILABILITY AND ACCEPTABILITY OF SPRUCE BUDWORM EGGS TO PARASITISM BY THE EGG PARASITOID, TRICHOGRAMMA MINUTUM (HYMENOPTERA: TRICHOGRAMMATIDAE)

The Canadian Entomologist ◽

10.4039/ent114657-8 ◽

1982 ◽

Vol 114 (8) ◽

pp. 657-666 ◽

Cited By ~ 17

Author(s):

Mark W. Houseweart ◽

Susan G. Southard ◽

Daniel T. Jennings

Keyword(s):

Spruce Budworm ◽

Egg Parasitoid ◽

Egg Development ◽

Egg Deposition ◽

Parasitism Rates ◽

Trichogramma Minutum ◽

Different Temperatures ◽

The Right ◽

Major Reduction

AbstractSpruce budworm egg deposition spanned 27 days during both 1979 and 1980. The egg deposition curve is essentially a normal bell-shaped distribution with a slight skew to the right. Spruce budworm eggs are most acceptable to T. minutum Riley for successful parasitism during the earlier stages of host–egg development. Parasitism rates at two different temperatures (21 °C and 27 °C) were significantly greater for 1- to 3-day-old eggs than for 6- to 8-day-old spruce budworm eggs. Major reduction in host–egg acceptability occurred after the fifth day at 21 °C and after the 4th day at 27 °C.

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Parasitoid community responds indiscriminately to fluctuating spruce budworm and other caterpillars on balsam fir

10.1101/615799 ◽

2019 ◽

Author(s):

Christopher J. Greyson-Gaito ◽

Kevin S. McCann ◽

Jochen Fründ ◽

Christopher J. Lucarotti ◽

M. Alex Smith ◽

...

Keyword(s):

Food Web ◽

Species Interactions ◽

Choristoneura Fumiferana ◽

Spruce Budworm ◽

Balsam Fir ◽

Critical Part ◽

Parasitoid Community ◽

Hardwood Trees ◽

Parasitism Rates ◽

The World

AbstractThe world is astoundingly variable, and individuals to whole communities must respond to variability to survive. One example of nature’s variability is the massive fluctuations in spruce budworm (Choristoneura fumiferana Clemens, Lepidoptera: Tortricidae) populations that occur over 35 years. We examined how the parasitoid community altered its parasitism of budworm and other caterpillar species in response to these fluctuations. Budworm and other caterpillar species were sampled from balsam fir in three plots for 14 years in Atlantic Canada, and then reared to identify any emerging parasitoids. We found that the parasitoid community showed a simple linear, indiscriminate response (i.e., no preference, where densities purely dictated parasitism rates) to changes in budworm densities relative to other caterpillar species on balsam fir. We also observed strong changes in topology and distributions of interaction strengths between the parasitoids, budworm and other caterpillar species as budworm densities fluctuated. Our study contributes to the suggestion that hardwood trees are a critical part of the budworm-parasitoid food web, where parasitoids attack other caterpillar species on hardwood trees when budworm populations are low. Taken together, our study shows that a parasitoid community collectively alters species interactions in response to variable budworm densities, fundamentally shifting food web pathways.

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Parasitoid community responds indiscriminately to fluctuating spruce budworm (Lepidoptera: Tortricidae) and other caterpillars on balsam fir (Pinaceae)

The Canadian Entomologist ◽

10.4039/tce.2021.14 ◽

2021 ◽

pp. 1-15

Author(s):

Christopher J. Greyson-Gaito ◽

Kevin S. McCann ◽

Jochen Fründ ◽

Christopher J. Lucarotti ◽

M. Alex Smith ◽

...

Keyword(s):

Food Web ◽

Species Interactions ◽

Choristoneura Fumiferana ◽

Spruce Budworm ◽

Balsam Fir ◽

Critical Part ◽

Parasitoid Community ◽

Hardwood Trees ◽

Parasitism Rates ◽

The World

Abstract The world is astoundingly variable, and organisms – from individuals to whole communities – must respond to variability to survive. One example of nature’s variability is the fluctuations in populations of spruce budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae), which cycle every 35 years. In this study, we examined how a parasitoid community altered its parasitism of budworm and other caterpillar species in response to these fluctuations. Budworm and other caterpillar species were sampled from balsam fir (Pinaceae) in three plots for 14 years in Atlantic Canada, then were reared to identify any emerging parasitoids. We found that the parasitoid community generally showed an indiscriminate response (i.e., no preference, where frequencies dictated parasitism rates) to changes in budworm frequencies relative to other caterpillar species on balsam fir. We also observed changes in topology and distributions of interaction strengths between the parasitoids, budworm, and other caterpillar species as budworm frequencies fluctuated. Our study contributes to the hypothesis that hardwood trees are a critical part of the budworm–parasitoid food web, where parasitoids attack other caterpillar species on hardwood trees when budworm populations are low. Taken together, our results show that a parasitoid community collectively alters species interactions in response to variable budworm frequencies, thereby fundamentally shifting food-web pathways.

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FIELD RELEASES OF TRICHOGRAMMA MINUTUM (HYMENOPTERA: TRICHOGRAMMATIDAE) FOR SUPPRESSION OF EPIDEMIC SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE), EGG POPULATIONS IN MAINE

The Canadian Entomologist ◽

10.4039/ent1161357-10 ◽

1984 ◽

Vol 116 (10) ◽

pp. 1357-1366 ◽

Cited By ~ 9

Author(s):

Mark W. Houseweart ◽

Daniel T. Jennings ◽

Robert K. Lawrence

Keyword(s):

Point Source ◽

Choristoneura Fumiferana ◽

Single Point ◽

Spruce Budworm ◽

Point Sources ◽

Slight Improvement ◽

Parasitism Rates ◽

Trichogramma Minutum ◽

Multiple Releases ◽

Better Than

AbstractTrichogramma minutum Riley was released in the field for suppression of epidemic spruce budworm, Choristoneura fumiferana (Clemens), egg populations in Maine from 1977 to 1981. Commercially reared California-strain T. minutum were released from the ground at single-point sources in 1977. In 1978, using 4-point-source releases, we found that the native Maine-strain performed better than the California strain. In 1979, broadcast and multiple releases from the ground gave slight improvement in parasitism over 4-point releases. In 1981, three closely timed, aerially broadcast releases from a helicopter yielded increases in parasitism rates significantly higher than those in control plots, but not sufficient to suppress epidemic spruce budworm populations. Important variables and suggestions for future aerial releases are discussed.

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Soil and climate equally contribute to changes in the species compositions of Brazilian dry forests across 300 km

Journal of Plant Ecology ◽

10.1093/jpe/rtz059 ◽

2020 ◽

Vol 13 (2) ◽

pp. 171-176

Author(s):

Daniel M Arruda ◽

Luiz F S Magnago ◽

Ricardo R C Solar ◽

Reinaldo Duque-Brasil ◽

Priscyla M S Rodrigues ◽

...

Keyword(s):

Spatial Structure ◽

Species Composition ◽

Beta Diversity ◽

Species Turnover ◽

Spatial Scales ◽

Dry Forest ◽

Conservation Strategies ◽

Dry Forests ◽

Forest Patches ◽

Forest Diversity

Abstract Aims Understanding the factors that control biodiversity distributions at different spatial scales has been a key challenge for conservation efforts. That biodiversity, reflected in differences in species compositions among sites (beta diversity), can be derived from species replacement (turnover) and is driven by multiple factors. Here, we sought to tackle this issue through two questions related to threatened Brazilian seasonally dry forests: (i) what is the contribution of species turnover to beta diversity? and (ii) which factors drive variations in species compositions among forest patches? Methods We sampled tree species and environmental variables (soils and climate) in 17 dry forest patches spaced almost 300 km apart. We used the beta diversity partitioning framework to determine the contribution of turnover. We used redundancy analysis, with properly controlled spatial structure, to assess the contributions of the environmental and spatial factors to the variations of the species composition. Important Findings Beta diversity among the patches was mainly represented by the turnover component (98.2%), with Simpson dissimilarity superior to other regions of the country (means of 0.89 and 0.71 in multiple site and pairwise measures, respectively). The environmental factors measured explained more than space, representing 30.3% of the variation of the species composition, of which 28.1% was nonspatially structured. We suggest that 300 km represents a threshold at which edaphic and climatic predictors have similar effects in determining community turnover (14.9% and 12.6%, respectively, without spatial structure). Thus, conservation strategies should be considered across landscapes to effectively protect tropical forest diversity, as even considering the different climatic aspects covered by the scale, landscaped edaphic varieties are important drivers of species turnover.

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A Remote Sensing Approach to Understanding Patterns of Secondary Succession in Tropical Forest

Remote Sensing ◽

10.3390/rs13112148 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2148

Author(s):

Eric Chraibi ◽

Haley Arnold ◽

Sandra Luque ◽

Amy Deacon ◽

Anne E. Magurran ◽

...

Keyword(s):

Remote Sensing ◽

Secondary Succession ◽

Field Data ◽

Spatial Scales ◽

Primary Forest ◽

Anthropogenic Pressures ◽

Ecological Processes ◽

Forest Diversity ◽

Alpha And Beta Diversity ◽

Landscape Level

Biodiversity monitoring and understanding ecological processes on a global scale is a major challenge for biodiversity conservation. Field assessments commonly used to assess patterns of biodiversity and habitat condition are costly, challenging, and restricted to small spatial scales. As ecosystems face increasing anthropogenic pressures, it is important that we find ways to assess patterns of biodiversity more efficiently. Remote sensing has the potential to support understanding of landscape-level ecological processes. In this study, we considered cacao agroforests at different stages of secondary succession, and primary forest in the Northern Range of Trinidad, West Indies. We assessed changes in tree biodiversity over succession using both field data, and data derived from remote sensing. We then evaluated the strengths and limitations of each method, exploring the potential for expanding field data by using remote sensing techniques to investigate landscape-level patterns of forest condition and regeneration. Remote sensing and field data provided different insights into tree species compositional changes, and patterns of alpha- and beta-diversity. The results highlight the potential of remote sensing for detecting patterns of compositional change in forests, and for expanding on field data in order to better understand landscape-level patterns of forest diversity.

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High spatial resolution x-ray microanalysis of interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137793 ◽

1995 ◽

Vol 53 ◽

pp. 284-285

Author(s):

J. R. Michael

Keyword(s):

Spatial Resolution ◽

Electron Probe ◽

Solid Angle ◽

Collection Efficiency ◽

Spatial Scales ◽

Energy Dispersive Spectrometer ◽

X Rays ◽

X Ray ◽

Probe Size ◽

Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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Spatial regularities between non-immigrant and immigrant numbers in Canada

MIGRATION LETTERS ◽

10.33182/ml.v11i1.171 ◽

2014 ◽

Vol 11 (1) ◽

pp. 90-100

Author(s):

Yigit Aydede

Keyword(s):

Fixed Effects ◽

Spatial Scales ◽

National Scale ◽

Pooled Data

The present study intends to reveal spatial regularities between non-immigrant and immigrant numbers in two different ways. First, it questions the existence of those regularities when spatial scales get finer. Second, it uses pooled data over four population censuses covering the period from 1991 to 2006, which enabled us to apply appropriate techniques to remove those unobserved fixed effects so that the estimations would accurately identify the linkage between local immigrant and non-immigrant numbers. The results provide evidence about the existence of negative spatial regularities between non-immigrant and immigrant numbers in Canada at national scale.

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