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Christensen T, Dyer LA, Forister ML, Bowers MD, Carper A, Teglas MB, Hurtado P, Smilanich AM. Host plant-mediation of viral transmission and its consequences for a native butterfly. Ecology 2024; 105:e4282. [PMID: 38483138 DOI: 10.1002/ecy.4282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 11/11/2023] [Accepted: 01/18/2024] [Indexed: 04/04/2024]
Abstract
Pathogens play a key role in insect population dynamics, contributing to short-term fluctuations in abundance as well as long-term demographic trends. Two key factors that influence the effects of entomopathogens on herbivorous insect populations are modes of pathogen transmission and larval host plants. In this study, we examined tritrophic interactions between a sequestering specialist lepidopteran, Euphydryas phaeton, and a viral pathogen, Junonia coenia densovirus, on its native host plant, Chelone glabra, and a novel host plant, Plantago lanceolata, to explore whether host plant mediates viral transmission, survival, and viral loads. A two-factor factorial experiment was conducted in the laboratory with natal larval clusters randomly assigned to either the native or novel host plant and crossed with either uninoculated controls or viral inoculation (20% of individuals in the cluster inoculated). Diapausing clusters were overwintered in the laboratory and checked weekly for mortality. At the end of diapause, all surviving individuals were reared to adulthood to estimate survivorship. All individuals were screened to quantify viral loads, and estimate horizontal transmission postmortem. To test for vertical transmission, adults were mated, and the progeny were screened for viral presence. Within virus-treated groups, we found evidence for both horizontal and vertical transmission. Larval clusters reared on the native host plant had slightly higher horizontal transmission. Survival probability was lower in clusters feeding on the native host plant, with inoculated groups reared on the native host plant experiencing complete mortality. Viral loads did not differ by the host plant, although viral loads decreased with increased sequestration of secondary compounds on both host plants. Our results indicate that the use of a novel host plant may confer fitness benefits in terms of survival and reduced viral transmission when larvae feeding on it are infected with this pathogen, supporting hypotheses of potential evolutionary advantages of a host range expansion in the context of tritrophic interactions.
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Affiliation(s)
- Tara Christensen
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - Lee A Dyer
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - Matthew L Forister
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - M Deane Bowers
- Department of Ecology and Evolutionary Biology and Museum of Natural History, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Adrian Carper
- Department of Ecology and Evolutionary Biology and Museum of Natural History, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Mike B Teglas
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Agriculture, Veterinary and Rangeland Sciences, University of Nevada, Reno, Nevada, USA
| | - Paul Hurtado
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Mathematics and Statistics, University of Nevada, Reno, Nevada, USA
| | - Angela M Smilanich
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
- Department of Biology, University of Nevada, Reno, Nevada, USA
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2
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St Leger RJ. Insects and their pathogens in a changing climate. J Invertebr Pathol 2021; 184:107644. [PMID: 34237297 DOI: 10.1016/j.jip.2021.107644] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 01/02/2021] [Accepted: 06/28/2021] [Indexed: 11/19/2022]
Abstract
The complex nature of climate change-mediated multitrophic interaction is an underexplored area, but has the potential to dramatically shift transmission and distribution of many insects and their pathogens, placing some populations closer to the brink of extinction. However, for individual insect-pathogen interactions climate change will have complicated hard-to-anticipate impacts. Thus, both pathogen virulence and insect host immunity are intrinsically linked with generalized stress responses, and in both pathogen and host have extensive trade-offs with nutrition (e.g., host plant quality), growth and reproduction. Potentially alleviating or exasperating these impacts, some pathogens and hosts respond genetically and rapidly to environmental shifts. This review identifies many areas for future research including a particular need to identify how altered global warming interacts with other environmental changes and stressors, and how consistent these impacts are across pathogens and hosts. With that achieved we would be closer to producing an overarching framework to integrate knowledge on all environmental interplay and infectious disease events.
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Affiliation(s)
- Raymond J St Leger
- Department of Entomology, University of Maryland, College Park, MD 20742, USA.
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3
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Mannu R, Cocco A, Luciano P, Lentini A. Influence of Bacillus thuringiensis application timing on population dynamics of gypsy moth in Mediterranean cork oak forests. PEST MANAGEMENT SCIENCE 2020; 76:1103-1111. [PMID: 31576666 DOI: 10.1002/ps.5622] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/26/2019] [Accepted: 09/14/2019] [Indexed: 05/27/2023]
Abstract
BACKGROUND The gypsy moth, Lymantria dispar, is one of the main pests of oak forests worldwide and causes extensive defoliation during its periodic outbreaks. In the Mediterranean region, control of gypsy moth populations in cork oak forests is based on application of Bacillus thuringiensis serovar kurstaki (Btk) formulations. This research investigated the effects of Btk applications carried out in two different population development phases on gypsy moth population dynamics. With this aim, temporal and spatial fluctuation patterns of L. dispar egg density were monitored in cork oak forests treated with Btk applications from 2004 to 2009 in Sardinia (Italy). RESULTS Applications undertaken during the progradation and culmination phases protected the oak canopies equally in the year of application, leading to a similar decrease in pest population density in the following year. However, the medium-term effectiveness of Btk differed between the two application timings, because only applications in the culmination phase caused a gradual decrease in L. dispar infestations throughout subsequent years. By contrast, when the application was undertaken during the progradation phase, population density increased again after 2-3 years. Moreover, Btk applications in the culmination phase reduced significantly the number of years in which gypsy moth density was damaging compared with those done in progradation. CONCLUSIONS Our results indicate that Btk applications during the culmination phase were more effective than those in the progradation period, because application in the latter case did not suppress the population, but only postponed the outbreak peak by 2-3 years. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Roberto Mannu
- Sezione di Patologia Vegetale ed Entomologia, Dipartimento di Agraria, Università degli Studi di Sassari, Sassari, Italy
| | - Arturo Cocco
- Sezione di Patologia Vegetale ed Entomologia, Dipartimento di Agraria, Università degli Studi di Sassari, Sassari, Italy
| | - Pietro Luciano
- Sezione di Patologia Vegetale ed Entomologia, Dipartimento di Agraria, Università degli Studi di Sassari, Sassari, Italy
| | - Andrea Lentini
- Sezione di Patologia Vegetale ed Entomologia, Dipartimento di Agraria, Università degli Studi di Sassari, Sassari, Italy
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4
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Kyle CH, Liu J, Gallagher ME, Dukic V, Dwyer G. Stochasticity and Infectious Disease Dynamics: Density and Weather Effects on a Fungal Insect Pathogen. Am Nat 2020; 195:504-523. [PMID: 32097039 PMCID: PMC10465172 DOI: 10.1086/707138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In deterministic models of epidemics, there is a host abundance threshold above which the introduction of a few infected individuals leads to a severe epidemic. Studies of weather-driven animal pathogens often assume that abundance thresholds will be overwhelmed by weather-driven stochasticity, but tests of this assumption are lacking. We collected observational and experimental data for a fungal pathogen, Entomophaga maimaiga, that infects the gypsy moth, Lymantria dispar. We used an advanced statistical-computing algorithm to fit mechanistic models to our data, such that different models made different assumptions about the effects of host density and weather on E. maimaiga epizootics (epidemics in animals). We then used Akaike information criterion analysis to choose the best model. In the best model, epizootics are driven by a combination of weather and host density, and the model does an excellent job of explaining the data, whereas models that allow only for weather effects or only for density-dependent effects do a poor job of explaining the data. Density-dependent transmission in our best model produces a host density threshold, but this threshold is strongly blurred by the stochastic effects of weather. Our work shows that host-abundance thresholds may be important even if weather strongly affects transmission, suggesting that epidemiological models that allow for weather have an important role to play in understanding animal pathogens. The success of our model means that it could be useful for managing the gypsy moth, an important pest of hardwood forests in North America.
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Affiliation(s)
- Colin H. Kyle
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
| | - Jiawei Liu
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
| | - Molly E. Gallagher
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
| | - Vanja Dukic
- Department of Applied Mathematics, University of Colorado, Boulder, Colorado 80309
| | - Greg Dwyer
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
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5
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Gazol A, Hernández-Alonso R, Camarero JJ. Patterns and Drivers of Pine Processionary Moth Defoliation in Mediterranean Mountain Forests. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00458] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Elkinton JS, Bittner TD, Pasquarella VJ, Boettner GH, Liebhold AM, Gould JR, Faubert H, Tewksbury L, Broadley HJ, Havill NP, Hajek AE. Relating Aerial Deposition of Entomophaga maimaiga Conidia (Zoopagomycota: Entomophthorales) to Mortality of Gypsy Moth (Lepidoptera: Erebidae) Larvae and Nearby Defoliation. ENVIRONMENTAL ENTOMOLOGY 2019; 48:1214-1222. [PMID: 31501859 DOI: 10.1093/ee/nvz091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Indexed: 06/10/2023]
Abstract
We collected data on mortality of late-instar gypsy moth, Lymantria dispar (L.), from outbreak populations over 4 wk in June 2017 at 10 sites in the New England region of the United States, along with estimated rainfall at these sites. Deposition of airborne conidia of the fungal pathogen, Entomophaga maimaiga Humber, Shimazu & R.S. Soper, was measured at these same sites as well as at seven other locations in New England. We also quantified the geographical distribution of gypsy moth-caused defoliation in New England in 2017 and 2018 from Landsat imagery. Weekly mortality of gypsy moth larvae caused by E. maimaiga correlated with local deposition of conidia from the previous week, but not with rainfall. Mortality from this pathogen reached a peak during the last 2 wk of gypsy moth larval development and always exceeded that caused by LdNPV, the viral pathogen of gypsy moth that has long been associated with gypsy moth outbreaks, especially prior to 1989. Cotesia melanoscela (Ratzeburg) was by far the most abundant parasitoid recovered and caused an average of 12.6% cumulative parasitism, but varied widely among sites. Deposition of E. maimaiga conidia was highly correlated with percent land area defoliated by gypsy moths within distances of 1 and 2 km but was not significantly correlated with defoliation at distances greater than 2 km. This is the first study to relate deposition of airborne conidia of E. maimaiga to mortality of gypsy moths from that agent.
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Affiliation(s)
- Joseph S Elkinton
- Department of Environmental Conservation and Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA
| | | | | | - George H Boettner
- Department of Environmental Conservation and Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA
| | - Andrew M Liebhold
- Northern Research Station, USDA Forest Service, Morgantown, WV
- Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Praha 6 - Suchdol, Czech Republic
| | - Juli R Gould
- USDA APHIS PPQ Science and Technology, Buzzards Bay, MA
| | - Heather Faubert
- Department of Plant Science and Entomology and URI Cooperative Extension, University of Rhode Island, Kingston, RI
| | - Lisa Tewksbury
- Department of Plant Science and Entomology and URI Cooperative Extension, University of Rhode Island, Kingston, RI
| | - Hannah J Broadley
- Department of Environmental Conservation and Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA
| | | | - Ann E Hajek
- Department of Entomology, Cornell University, Ithaca, NY
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7
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Haynes KJ, Walter JA, Liebhold AM. Population spatial synchrony enhanced by periodicity and low detuning with environmental forcing. Proc Biol Sci 2019; 286:20182828. [PMID: 31138079 DOI: 10.1098/rspb.2018.2828] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Explaining why fluctuations in abundances of spatially disjunct populations often are correlated through time is a major goal of population ecologists. We address two hypotheses receiving little to no testing in wild populations: (i) that population cycling facilitates synchronization given weak coupling among populations, and (ii) that the ability of periodic external forces to synchronize oscillating populations is a function of the mismatch in timescales (detuning) between the force and the population. Here, we apply new analytical methods to field survey data on gypsy moth outbreaks. We report that at timescales associated with gypsy moth outbreaks, spatial synchrony increased with population periodicity via phase locking. The extent to which synchrony in temperature and precipitation influenced population synchrony was associated with the degree of mismatch in dominant timescales of oscillation. Our study provides new empirical methods and rare empirical evidence that population cycling and low detuning can promote population spatial synchrony.
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Affiliation(s)
- Kyle J Haynes
- 1 The Blandy Experimental Farm, University of Virginia , Boyce, VA , USA.,2 Department of Environmental Sciences, University of Virginia , Charlottesville, VA , USA
| | - Jonathan A Walter
- 2 Department of Environmental Sciences, University of Virginia , Charlottesville, VA , USA
| | - Andrew M Liebhold
- 3 US Forest Service Northern Research Station , Morgantown, WV 26505 , USA.,4 Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences , Praha 6 - Suchdol, Czechia 16521 , Czech Republic
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8
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Páez DJ, Dukic V, Dushoff J, Fleming-Davies A, Dwyer G. Eco-Evolutionary Theory and Insect Outbreaks. Am Nat 2017; 189:616-629. [PMID: 28514636 DOI: 10.1086/691537] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Eco-evolutionary theory argues that population cycles in consumer-resource interactions are partly driven by natural selection, such that changes in densities and changes in trait values are mutually reinforcing. Evidence that the theory explains cycles in nature, however, is almost nonexistent. Experimental tests of model assumptions are logistically impractical for most organisms, while for others, evidence that population cycles occur in nature is lacking. For insect baculoviruses in contrast, tests of model assumptions are straightforward, and there is strong evidence that baculoviruses help drive population cycles in many insects, including the gypsy moth that we study here. We therefore used field experiments with the gypsy moth baculovirus to test two key assumptions of eco-evolutionary models of host-pathogen population cycles: that reduced host infection risk is heritable and that it is costly. Our experiments confirm both assumptions, and inserting parameters estimated from our data into eco-evolutionary insect-outbreak models gives cycles closely resembling gypsy moth outbreak cycles in North America, whereas standard models predict unrealistic stable equilibria. Our work shows that eco-evolutionary models are useful for explaining outbreaks of forest insect defoliators, while widespread observations of intense selection on defoliators in nature and of heritable and costly resistance in defoliators in the lab together suggest that eco-evolutionary dynamics may play a general role in defoliator outbreaks.
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9
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Hajek AE, van Nouhuys S. Fatal diseases and parasitoids: from competition to facilitation in a shared host. Proc Biol Sci 2016; 283:rspb.2016.0154. [PMID: 27053740 DOI: 10.1098/rspb.2016.0154] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/07/2016] [Indexed: 01/06/2023] Open
Abstract
Diverse parasite taxa share hosts both at the population level and within individual hosts, and their interactions, ranging from competitive exclusion to facilitation, can drive community structure and dynamics. Emergent pathogens have the potential to greatly alter community interactions. We found that an emergent fungal entomopathogen dominated pre-existing lethal parasites in populations of the forest defoliating gypsy moth,Lymantria dispar The parasite community was composed of the fungus and four parasitoid species that only develop successfully after they kill the host, and a virus that produces viable propagules before the host has died. A low-density site was sampled over 17 years and compared with 66 sites across a range of host densities, including outbreaks. The emergent fungal pathogen and competing parasitoids rarely co-infected host individuals because each taxa must kill its host. The virus was not present at low host densities, but successfully co-infected with all other parasite species. In fact, there was facilitation between the virus and one parasitoid species hosting a polydnavirus. This newly formed parasite community, altered by an emergent pathogen, is shaped both by parasite response to host density and relative abilities of parasites to co-inhabit the same host individuals.
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Affiliation(s)
- Ann E Hajek
- Department of Entomology, Cornell University, Ithaca, NY 14853-2601, USA
| | - Saskya van Nouhuys
- Department of Entomology, Cornell University, Ithaca, NY 14853-2601, USA Department of Biosciences, University of Helsinki, Helsinki 00014, Finland
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10
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Myers JH, Cory JS. Ecology and evolution of pathogens in natural populations of Lepidoptera. Evol Appl 2016; 9:231-47. [PMID: 27087850 PMCID: PMC4780379 DOI: 10.1111/eva.12328] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/19/2015] [Indexed: 01/25/2023] Open
Abstract
Pathogens are ubiquitous in insect populations and yet few studies examine their dynamics and impacts on host populations. We discuss four lepidopteran systems and explore their contributions to disease ecology and evolution. More specifically, we elucidate the role of pathogens in insect population dynamics. For three species, western tent caterpillars, African armyworm and introduced populations of gypsy moth, infection by nucleopolyhedrovirus (NPV) clearly regulates host populations or reduces their outbreaks. Transmission of NPV is largely horizontal although low levels of vertical transmission occur, and high levels of covert infection in some cases suggest that the virus can persist in a nonsymptomatic form. The prevalence of a mostly vertically transmitted protozoan parasite, Ophryocystis elektroscirrha, in monarch butterflies is intimately related to their migratory behaviour that culls highly infected individuals. Virulence and transmission are positively related among genotypes of this parasite. These systems clearly demonstrate that the interactions between insects and pathogens are highly context dependent. Not only is the outcome a consequence of changes in density and genetic diversity: environmental factors, particularly diet, can have strong impacts on virulence, transmission and host resistance or tolerance. What maintains the high level of host and pathogen diversity in these systems, however, remains a question.
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Affiliation(s)
- Judith H. Myers
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Jenny S. Cory
- Department of Biological SciencesSimon Fraser UniversityBurnabyBCCanada
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11
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Allstadt AJ, Liebhold AM, Johnson DM, Davis RE, Haynes KJ. Temporal variation in the synchrony of weather and its consequences for spatiotemporal population dynamics. Ecology 2015; 96:2935-46. [DOI: 10.1890/14-1497.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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12
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Asaro C, Chamberlin LA. Outbreak History (1953-2014) of Spring Defoliators Impacting Oak-Dominated Forests in Virginia, with Emphasis on Gypsy Moth (Lymantria disparL.) and Fall Cankerworm (Alsophila pometariaHarris). ACTA ACUST UNITED AC 2015. [DOI: 10.1093/ae/tmv043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Hajek AE, Tobin PC, Haynes KJ. Replacement of a dominant viral pathogen by a fungal pathogen does not alter the collapse of a regional forest insect outbreak. Oecologia 2014; 177:785-797. [PMID: 25510217 DOI: 10.1007/s00442-014-3164-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 11/12/2014] [Indexed: 11/29/2022]
Abstract
Natural enemies and environmental factors likely both influence the population cycles of many forest-defoliating insect species. Previous work suggests precipitation influences the spatiotemporal patterns of gypsy moth outbreaks in North America, and it has been hypothesized that precipitation could act indirectly through effects on pathogens. We investigated the potential role of climatic and environmental factors in driving pathogen epizootics and parasitism at 57 sites over an area of ≈72,300 km(2) in four US mid-Atlantic states during the final year (2009) of a gypsy moth outbreak. Prior work has largely reported that the Lymantria dispar nucleopolyhedrovirus (LdNPV) was the principal mortality agent responsible for regional collapses of gypsy moth outbreaks. However, in the gypsy moth outbreak-prone US mid-Atlantic region, the fungal pathogen Entomophaga maimaiga has replaced the virus as the dominant source of mortality in dense host populations. The severity of the gypsy moth population crash, measured as the decline in egg mass densities from 2009 to 2010, tended to increase with the prevalence of E. maimaiga and larval parasitoids, but not LdNPV. A significantly negative spatial association was detected between rates of fungal mortality and parasitism, potentially indicating displacement of parasitoids by E. maimaiga. Fungal, viral, and parasitoid mortality agents differed in their associations with local abiotic and biotic conditions, but precipitation significantly influenced both fungal and viral prevalence. This study provides the first spatially robust evidence of the dominance of E. maimaiga during the collapse of a gypsy moth outbreak and highlights the important role played by microclimatic conditions.
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Affiliation(s)
- Ann E Hajek
- Department of Entomology, Cornell University, Ithaca, NY, 14853-2601, USA.
| | - Patrick C Tobin
- Northern Research Station, USDA Forest Service, Morgantown, WV, 26505, USA.,School of Environmental and Forest Sciences, University of Washington, Seattle, WA, 98195-2100, USA
| | - Kyle J Haynes
- Department of Environmental Sciences, Blandy Experimental Farm, University of Virginia, Boyce, VA, 22620, USA
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Kistner EJ, Belovsky GE. Host dynamics determine responses to disease: additive vs. compensatory mortality in a grasshopper–pathogen system. Ecology 2014. [DOI: 10.1890/13-0969.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Reilly JR, Hajek AE, Liebhold AM, Plymale R. Impact of Entomophaga maimaiga (Entomophthorales: Entomophthoraceae) on outbreak gypsy moth populations (Lepidoptera: Erebidae): the role of weather. ENVIRONMENTAL ENTOMOLOGY 2014; 43:632-641. [PMID: 24805137 DOI: 10.1603/en13194] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The fungal pathogen Entomophaga maimaiga Humber, Shimazu, and Soper is prevalent in gypsy moth [Lymantria dispar (L.)] populations throughout North America. To understand how weather-related variables influence gypsy moth-E. maimaiga interactions in the field, we measured fungal infection rates at 12 sites in central Pennsylvania over 3 yr, concurrently measuring rainfall, soil moisture, humidity, and temperature. Fungal mortality was assessed using both field-collected larvae and laboratory-reared larvae caged on the forest floor. We found significant positive effects of moisture-related variables (rainfall, soil moisture, and relative humidity) on mortality due to fungal infection in both data sets, and significant negative effects of temperature on the mortality of field-collected larvae. Lack of a clear temperature relationship with the mortality of caged larvae may be attributable to differential initiation of infection by resting spores and conidia or to microclimate effects. These relationships may be helpful in understanding how gypsy moth dynamics vary across space and time, and in forecasting how the gypsy moth and fungus will interact as they move into warmer or drier areas, or new weather conditions occur due to climate change.
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Affiliation(s)
- James R Reilly
- Department of Entomology, Cornell University, Ithaca,NY14853-2601, USA
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16
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Reilly JR, Elderd BD. Effects of biological control on long-term population dynamics: identifying unexpected outcomes. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12181] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- James R. Reilly
- Department of Entomology; Rutgers University; New Brunswick NJ 08901 USA
- Department of Biological Sciences; Louisiana State University; Baton Rouge LA 70803 USA
| | - Bret D. Elderd
- Department of Biological Sciences; Louisiana State University; Baton Rouge LA 70803 USA
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