Observations on the Puddling Behavior of the Canadian Tiger Swallowtail Butterfly, \u3ci\u3ePapilio Glaucus Canadensis\u3c/i\u3e in Northern Michigan

(excerpt) The occurrence of puddling behavior in Lepidoptera has been reviewed by M. J. Norris (1936) by J. A. Downes (1973) and by P. H. Adler (1982). Butterflies have been previously reported on mammalian dung, urine, perspiration, saliva, salt, blood, campfire ashes, aphid honeydew, tree sap and animal carrion. The rarity of female puddling in butterflies, particularly the tiger swallowtail (Papilio glaucus) has been recently addressed by two studies (Berger and Lederhouse 1985, Scriber 1987)

Can the nutrient dynamics of a northern hardwood forest explain variation in its trophic structure?

Background/Question/Methods: A time series of Lepidoptera larvae (caterpillar) abundance and biomass in the northern hardwood forests of central New Hampshire, USA, shows large interannual fluctuations in aggregated caterpillar biomass (52-fold variation in mg caterpillars/ 8000 leaves) that were spatially correlated across a regional landscape. Primary production of these mature forests has not varied over this period, and many hundreds of Lepidoptera species share comparatively few host plants. Therefore, interannual changes in nutritional quality of even one host plant species may be capable of generating correlated population dynamics for many species in the Lepidoptera community. We tested the hypothesis that variation in soil nutrient availability influences foliar chemistry and ultimately produces a bottom-up force capable influencing the aggregated biomass of the forest's dominant herbivores.

Results/Conclusions: Over a period of four years, measures of nutritional quality for herbivores in three of the forest's four dominant understory tree species (Acer saccharum, Acer pensylvanicum, and Viburnum alnifolium) displayed considerable variation that was consistent across the landscape. Foliar nitrogen (N) content and two metrics of secondary metabolite concentration—total phenolics and condensed tannin—all varied by up to 20% among years. Resin bag extracts of NH4+, NO2- /NO3- and PO4+ showed soil mineral nutrient availability displayed six-fold variation that was consistent with the pattern in foliar N, and a whole tree in situ fertilization experimental manipulation produced rapid effects on foliar chemistry. Finally, variation in the forewing lengths of free-flying moths showed an interannual concordance among species within the group of early season feeders that was also consistent with patterns in foliar quality—suggesting collections of species experience correlated variations in larval growth performance.
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Extreme climatic events affect populations of Asian chestnut gall wasps, Dryocosmus kuriphilus, but do not stop the spread

[EN] Global climate change affects the frequency of extreme weather events that can influence plant–insect interactions. We evaluated how the late-spring frost and severe drought that occurred in Spain in 2017 affected interactions between the invasive gall insect, Dryocosmus kuriphilus, and the native tree, Castanea sativa. We assessed effects on insect survival, fertility, population growth, and effects through changes in tree palatability and in other pests and pathogens. Late-spring frost reduced D. kuriphilus to 25–40% of previous abundance. Wasp populations recovered rapidly (>7-fold in 3 years), consistent with density-dependence in population dynamics. Larvae affected by freeze or drought were smaller. Female fecundity was affected by the freeze 1 year later. Late-spring frosts and severe drought affected leaf size and physiology. Water content was higher within galls, but nitrogen was higher within galls in non-freeze plots after weather conditions improved. Freezing also influenced the secondary chemistry of leaves. Phenol concentrations were lower, and terpenes higher, in frozen plots, while condensed tannins remained the same. Condensed tannins were reduced to half in the drought year. Freezing had limited effects on damage from other pests and pathogens. Our work expands understanding of how climate and weather affects forest pestsSIThis work was supported by FEDER/Spanish Ministry of Economy and Competitiveness Research (Grant AGL2016-76262-R). Diana Blanco, Elva Rico, and Naidu Lombardero provided assistance in the field and in the lab. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this pape

Extreme climatic events affect populations of Asian chestnut gall wasps, Dryocosmus kuriphilus, but do not stop the spread

1 Global climate change affects the frequency of extreme weather events that can influence plant–insect interactions. 2 We evaluated how the late-spring frost and severe drought that occurred in Spain in 2017 affected interactions between the invasive gall insect, Dryocosmus kuriphilus, and the native tree, Castanea sativa. We assessed effects on insect survival, fertility, population growth, and effects through changes in tree palatability and in other pests and pathogens. 3 Late-spring frost reduced D. kuriphilus to 25–40% of previous abundance. Wasp populations recovered rapidly (>7-fold in 3 years), consistent with density-dependence in population dynamics. 4 Larvae affected by freeze or drought were smaller. Female fecundity was affected by the freeze 1 year later. 5 Late-spring frosts and severe drought affected leaf size and physiology.Water content was higher within galls, but nitrogen was higher within galls in non-freeze plots after weather conditions improved. 6 Freezing also influenced the secondary chemistry of leaves. Phenol concentrations were lower, and terpenes higher, in frozen plots, while condensed tannins remained the same. Condensed tannins were reduced to half in the drought year. 7 Freezing had limited effects on damage from other pests and pathogens. 8 Our work expands understanding of how climate and weather affects forest pestsThis work was supported by FEDER/Spanish Ministry of Economy and Competitiveness Research (Grant AGL2016-76262-R)S

Host Use Patterns by the European Woodwasp, Sirex noctilio, in Its Native and Invaded Range

Accelerating introductions of forest insects challenge decision-makers who might or might not respond with surveillance programs, quarantines, eradication efforts, or biological control programs. Comparing ecological controls on indigenous vs. introduced populations could inform responses to new introductions. We studied the European woodwasp, Sirex noctilio, which is not a pest in its native forests, is a serious invasive pest in the southern hemisphere, and now has an uncertain future in North America after its introduction there. Indigenous populations of S. noctilio (in Galicia, Spain) resembled those in New York in that S. noctilio were largely restricted to suppressed trees that were also dying for other reasons, and still only some dying trees showed evidence of S. noctilio: 20–40% and 35–51% in Galicia and New York, respectively. In both areas, P. sylvestris (native to Europe) was the species most likely to have attacks in non-suppressed trees. P. resinosa, native to North America, does not appear dangerously susceptible to S. noctilio . P. radiata, which sustains high damage in the southern hemisphere, is apparently not innately susceptible because in Galicia it was less often used by native S. noctilio than either native pine (P. pinaster and P. sylvestris ). Silvicultural practices in Galicia that maintain basal area at 25–40 m2/ha limit S. noctilio abundance. More than 25 species of other xylophagous insects feed on pine in Galicia, but co-occurrences with S. noctilio were infrequent, so strong interspecific competition seemed unlikely. Evidently, S. noctilio in northeastern North America will be more similar to indigenous populations in Europe, where it is not a pest, than to introduced populations in the southern hemisphere, where it is. However, S. noctilio populations could behave differently when they reach forests of the southeastern U.S., where tree species, soils, climate, ecology, management, and landscape configurations of pine stands are different

Defensive patterns of chestnut genotypes (Castanea spp.) against the gall wasp, Dryocosmus kuriphilus

Plants draw from various genetically controlled defenses to protect against herbivores and pathogens. The efficacy of alternative defenses can vary with the biology and phylogeny of the enemy. Dryocosmus kuriphilus, an invasive gall maker native to China, has become one of the main pests of chestnut trees around the world. We studied genetic variation in resistance and susceptibility to D. kuriphilus within a replicated blocked planting of 12 chestnut genotypes established in Galicia, Spain in 2004. We found very high genetic variation in susceptibility to D. kuriphilus. We evaluated if the variation was due to host selection by the wasp, differential efficacy of inducible defenses in the trees, or variability in susceptibility of the plant to manipulation by the gallmaker. We assessed host selection by counting number of eggs laid by females in tree buds and comparing preferences with phytochemistry. We also measured inducible changes in phytochemistry within and around galls, gall physical characteristics, parasitism, and insect fitness. The effective defense mechanisms in resistant genotypes involved (1) hypersensitive reactions to eggs or neonates within buds and (2) early precise abscission of nascent galls from expanding leaves. Surprisingly, the genetic resistance to D. kuriphilus of the chestnut genotypes we tested was not related to phenols, terpenes, and primary nutritionSIThis work was supported by FEDER/Spanish Ministry of Economy and Competitiveness (Research Grant AGL2016-76262-R)

Impact of Minimum Winter Temperatures on the Population Dynamics of Dendroctonus Frontalis

Predicting population dynamics is a fundamental problem in applied ecology. Temperature is a potential driver of short-term population dynamics, and temperature data are widely available, but we generally lack validated models to predict dynamics based upon temperatures. A generalized approach involves estimating the temperatures experienced by a population, characterizing the demographic consequences of physiological responses to temperature, and testing for predicted effects on abundance. We employed this approach to test whether minimum winter temperatures are a meaningful driver of pestilence from Dendroctonus frontalis (the southern pine beetle) across the southeastern United States. A distance-weighted interpolation model provided good, spatially explicit, predictions of minimum winter air temperatures (a putative driver of beetle survival). A Newtonian heat transfer model with empirical cooling constants indicated that beetles within host trees are buffered from the lowest air temperatures by approximately 1-4 degrees C (depending on tree diameter and duration of cold bout). The life stage structure of beetles in the most northerly outbreak in recent times (New Jersey) were dominated by prepupae, which were more cold tolerant (by \u3e3 degrees C) than other life stages. Analyses of beetle abundance data from 1987 to 2005 showed that minimum winter air temperature only explained 1.5% of the variance in interannual growth rates of beetle populations, indicating that it is but a weak driver of population dynamics in the southeastern United States as a whole. However, average population growth rate matched theoretical predictions of a process-based model of winter mortality from low temperatures; apparently our knowledge of population effects from winter temperatures is satisfactory, and may help to predict dynamics of northern populations, even while adding little to population predictions in southern forests. Recent episodes of D. frontalis outbreaks in northern forests may have been allowed by a warming trend from 1960 to 2004 of 3.3 degrees C in minimum winter air temperatures in the southeastern United States. Studies that combine climatic analyses, physiological experiments, and spatially replicated time series of population abundance can improve population predictions, contribute to a synthesis of population and physiological ecology, and aid in assessing the ecological consequences of climatic trends

Cold Tolerance of Four Species of Bark Beetle (Coleoptera:Scolytidae) in North America

ABSTRACT We investigated the overwintering biology of four temperate-latitude bark beetles: Dendroctonus frontalis Zimmermann, Ips pini (Say), I. grandicollis (Eichhoff), and I. perroti Swaine. All four species were freeze-susceptible. However, there was variation within and among species in overwintering biology that related to their geographic distribution. D. frontalis and southern populations of I. grandicollis continued to reproduce and develop under the bark of their host plants throughout the winter and did not show any seasonal adjustments in their lower lethal temperatures: mean supercooling point Ϯ SD ϭ Ϫ12.15 Ϯ 4.02 and Ϫ12.25 Ϯ 2.50ЊC. In contrast, northern populations of I. grandicollis and I. pini employ a behavioral strategy in which adults migrate to the forest soil, where they are insulated from temperature extremes by litter and snow. Furthermore, adult supercooling points of both northern populations declined from about Ϫ13ЊC in summer to about Ϫ17ЊC in early winter. A concomitant decline in lipid content suggests that lipid metabolism may be involved in seasonal adjustments of cold tolerance in I. pini. An assortment of temperature manipulations failed to provide any evidence of cold tolerance acclimation. Immatures, which remain in the inner bark of their host trees, have lower lethal temperatures of Ϫ5 to Ϫ12ЊC, and are especially vulnerable to mortality from freezing. I. perroti, a northerly distributed species, had similar cold tolerance and overwinter behavior as northern populations of the other two Ips species. Winter mortality from freezing could be an important determinant of population dynamics in all four species. Understanding variations in cold tolerance and overwinter behavior among insects species may help predict population dynamics and distribution of potential pests

Nitrogen Budgets of Phloem-Feeding Bark Beetles with and without Symbiotic Fungi

The nitrogen content of plant tissue is low relative to that of herbivores; as a consequence, dietary N can limit the growth and reproduction of herbivores and select for attributes that increase N acquisition. Bark beetles face a particularly severe challenge because the phloem that they consume is very low in nitrogen and phosphorus relative to their requirements. We quantified variation in the phloem concentrations of N and P in the host tree, Pinus taeda, and evaluated the following hypotheses regarding the role of symbiotic fungi in nutrient budgets of the herbivore Dendroctonus frontalis: D. frontalis experience variation in phloem nutrient concentrations across several spatial scales (H1); mycangial fungi enhance the diet of D. frontalis larvae by contributing to the acquisition of N and P (H2); Ophiostoma minus, an apparently antagonistic fungal symbiont, hinders D. frontalis larvae because it does not enhance nutrient concentrations of the phloem as much as mycangial fungi do (H3); and larvae of bark beetle species that lack mycangial fungi must consume more phloem to accomplish the same growth as larvae of D. frontalis (H4). In addition, we developed a general model for the N budgets of herbivorous insects that identifies the possible combinations of dietary and physiological parameters that can allow developmental success on low‐nutrient diets. Spatial variation in phloem N was mostly at the level of trees within sites (a scale of meters) while P mostly varied among sites (a scale of kilometers). Trees with higher N content produced larger D. frontalis adults. Prior to infestation by beetles, phloem nutrient concentrations were very uniform within trees and very low relative to that of the bark beetles (N and P concentrations of D. frontalis adults were 28 and 8 times greater, respectively). During infestation, phloem nutrient concentrations increased overall and became highly variable within trees. Nitrogen concentrations increased from 0.40 ± 0.01% (mean ± 1 se) in uninfested phloem to 0.86 ± 0.03% in the phloem surrounding successfully developing D. frontalis larvae, which are typically associated with one or two species of mutualistic mycangial fungi. Nitrogen concentrations were intermediate in other microhabitats within infested trees, including regions with no adult colonization, with failed larval development, or colonized by the antagonistic bluestain fungus O. minus. We parameterized a general nutrient‐budget model for D. frontalis and a sympatric non‐mycangial bark beetle, Ips grandicollis, which indicated that (1) mycangial fungi provide their benefits by concentrating dietary N for larvae; (2) O. minus may exert its antagonistic effects on D. frontalis larvae by failing to concentrate dietary N as much as mycangial fungi do; (3) non‐mycangial bark beetles meet their N budgets through high consumption of unaltered, low‐N phloem; and (4) larvae should easily meet their P requirements with any combination of consumption rate and development time that allows them to meet their N requirements. Alternative strategies for N acquisition may have general consequences for the population dynamics and community interactions of bark beetles

Antagonisms, mutualisms and commensalisms affect outbreak dynamics of the southern pine beetle

Feedback from community interactions involving mutualisms are a rarely explored mechanism for generating complex population dynamics. We examined the effects of two linked mutualisms on the population dynamics of a beetle that exhibits outbreak dynamics. One mutualism involves an obligate association between the bark beetle, Dendroctonus frontalis and two mycangial fungi. The second mutualism involves Tarsonemus mites that are phoretic on D. frontalis ( commensal ), and a blue-staining fungus, Ophiostoma minus. The presence of O. minus reduces beetle larval survival ( antagonistic ) by outcompeting beetle-mutualistic fungi within trees yet supports mite populations by acting as a nutritional mutualist. These linked interactions potentially create an interaction system with the form of an endogenous negative feedback loop. We address four hypotheses: (1) Direct negative feedback: Beetles directly increase the abundance of O. minus, which reduces per capita reproduction of beetles. (2) Indirect negative feedback: Beetles indirectly increase mite abundance, which increases O. minus, which decreases beetle reproduction. (3) The effect of O. minus on beetles depends on mites, but mite abundance is independent of beetle abundance. (4) The effect of O. minus on beetles is independent of beetle and mite abundance. High Tarsonemus and O. minus abundances were strongly correlated with the decline and eventual local extinction of beetle populations. Manipulation experiments revealed strong negative effects of O. minus on beetles, but falsified the hypothesis that horizontal transmission of O. minus generates negative feedback. Surveys of beetle populations revealed that reproductive rates of Tarsonemus, O. minus, and beetles covaried in a manner consistent with strong indirect interactions between organisms. Co-occurrence of mutualisms embedded within a community may have stabilizing effects if both mutualisms limit each other. However, delays and/ or non-linearities in the interaction systems may result in large population fluctuations. © Springer-Verlag 2005