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Zilnik G, Cooper WR, Horton DR, Orpet R, Nottingham L, Hilton R, Adams C, Dickens KL, Halbert SE, Snyder J, Schmidt-Jeffris R. Seasonal activity of Trechnites insidiosus (Hymenoptera: Encyrtidae) and its host Cacopsylla pyricola (Hemiptera: Psyllidae) in pear. J Econ Entomol 2023; 116:1957-1968. [PMID: 37944058 DOI: 10.1093/jee/toad199] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 07/27/2023] [Accepted: 10/16/2023] [Indexed: 11/12/2023]
Abstract
Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) is the most expensive and challenging insect pest of commercial pear trees in the Pacific Northwest. Integrated pest management (IPM) programs are working toward relying more heavily on natural enemies to reduce insecticide use. Trechnites insidiosus (Crawford) (Hymenoptera: Encyrtidae) is the main parasitoid of C. pyricola, but little is known about its biology in the region. Developing sampling tools is important for the deployment of IPM programs, including monitoring of natural enemies. In this study, we examined 2 conventional monitoring methods: beat trays and yellow sticky cards, in addition to screened sticky cards and 3D-printed cylinder traps. Additionally, we tested an overwintering trap for the collection of parasitized C. pyricola. The trapping methods were tested in orchards in Oregon and Washington. Unscreened cards caught the most T. insidiosus and C. pyricola, followed by screened cards, cylinder traps, and then beat trays. Beat trays sometimes failed to catch any T. insidiosus, even when it was found in abundance via other methods. Screened cards and cylinder traps reduced bycatch and increased ease of identifying T. insidiosus. Specimens from the cylinder traps were also more suitable for use in molecular analysis. The overwintering traps were effective at capturing parasitized C. pyricola, but were highly variable year to year. The ideal trapping method will vary based on research needs (e.g., DNA preservation, reducing bycatch, catching higher numbers), but both screened sticky cards and cylinder traps were viable methods for monitoring T. insidiosus and its host.
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Affiliation(s)
- Gabriel Zilnik
- USDA-ARS, Arid Land Agricultural Research Center, 21881 North Cardon Lane, Maricopa, AZ 85138, USA
| | - W Rodney Cooper
- USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, 5230 Konnowac Pass Road, Wapato, WA 98951, USA
| | - David R Horton
- USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, 5230 Konnowac Pass Road, Wapato, WA 98951, USA
| | - Robert Orpet
- Department of Entomology, Tree Fruit Research and Extension Center, Washington State University, 1100 N Western Ave, Wenatchee, WA 98801, USA
| | - Louis Nottingham
- Department of Entomology, Northwestern Research and Extension Center, Washington State University, 16650 State Route 536, Mount Vernon, WA 98273, USA
| | - Richard Hilton
- Department of Horticulture, Southern Oregon Research and Extension Center, Oregon State University, 569 Hanley Rd, Central Point, OR 97502, USA
| | - Chris Adams
- Department of Horticulture, Mid-Columbia Agricultural Research and Extension Center, Oregon State University, 3005 Experiment Station Dr., Hood River, OR 97301, USA
| | - Katrina L Dickens
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, 1911 SW 34th St., Gainesville, FL 32608, USA
| | - Susan E Halbert
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, 1911 SW 34th St., Gainesville, FL 32608, USA
| | - James Snyder
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, 1911 SW 34th St., Gainesville, FL 32608, USA
| | - Rebecca Schmidt-Jeffris
- USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, 5230 Konnowac Pass Road, Wapato, WA 98951, USA
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DuPont ST, Strohm C, Kogan C, Hilton R, Nottingham L, Orpet R. Pear psylla and natural enemy thresholds for successful integrated pest management in pears. J Econ Entomol 2023; 116:1249-1260. [PMID: 37341151 PMCID: PMC10413998 DOI: 10.1093/jee/toad101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/23/2023] [Accepted: 05/25/2023] [Indexed: 06/22/2023]
Abstract
Pear psylla, Cacopsylla pyricola (Förster), is the most economically challenging pest of commercial pears in Washington and Oregon, the top producers of pears in the United States. The objective of this study was to quantify economic injury levels and thresholds for pear psylla. We used the relationship between pear psylla adult and nymph densities, and fruit downgraded due to psylla honeydew marking to identify injury levels. We calculated economic injury levels using the cost of downgraded fruit and average management costs (spray materials and labor). Using economic injury levels, we determined economic thresholds for pear psylla, which include predicted pest population growth, natural enemy predation, and anticipated delays between when pest populations are measured and when managers apply interventions. Economic thresholds generated by this study were 0.1-0.3 second-generation nymphs per leaf and 0.2-0.8 third-generation nymphs per leaf depending on predicted price and yield for insecticide applications at 1,300 pear psylla degree days in the second generation and 2,600 pear psylla degree days in the third generation. Natural enemy inaction thresholds identified by this study were 6 Deraeocoris brevis or 3 Campylomma verbasci immatures per 30 trays or 2 earwigs per trap for third-generation optional insecticide applications.
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Affiliation(s)
- S Tianna DuPont
- College of Agriculture and Natural Resources, Washington State University, Tree Fruit Research and Extension Center, 1100 N Western Ave, Wenatchee, WA 98801, USA
| | - Chris Strohm
- College of Agriculture and Natural Resources, Washington State University, Tree Fruit Research and Extension Center, 1100 N Western Ave, Wenatchee, WA 98801, USA
| | - Clark Kogan
- Department of Mathematics and Statistics, Washington State University, Statistics, Spokane WA, USA
| | - Rick Hilton
- College of Agricultural Sciences, Oregon State University, Southern Oregon Research and Extension Center, 569 Hanley Rd, Central Point, Oregon 97502, USA
| | - Louis Nottingham
- Department of Entomology, Washington State University, Northwestern WA Research and Extension Center, 16650 State Route 536, Mount Vernon, WA 98273, USA
| | - Robert Orpet
- College of Agriculture and Natural Resources, Washington State University, Tree Fruit Research and Extension Center, 1100 N Western Ave, Wenatchee, WA 98801, USA
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Rougemont Q, Huber B, Martin S, Whibley A, Estrada C, Solano D, Orpet R, McMillan WO, Frérot B, Joron M. Subtle introgression footprints at the end of the speciation continuum in a clade of Heliconius butterflies. Mol Biol Evol 2023:msad166. [PMID: 37467472 PMCID: PMC10375063 DOI: 10.1093/molbev/msad166] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 05/24/2023] [Accepted: 07/10/2023] [Indexed: 07/21/2023] Open
Abstract
Quantifying gene flow between lineages at different stages of the speciation continuum is central to understanding speciation. Heliconius butterflies have undergone an adaptive radiation in wing colour patterns driven partly by natural selection for local mimicry. Colour patterns are also known to be used as assortative mating cues. Therefore, wing pattern divergence is considered to play a role in speciation. A corollary is that mimicry between closely-related species may be associated with hybridization and interfere with reproductive isolation. Here, we take a multifaceted approach to explore speciation history, species boundaries, and traits involved in species differentiation between the two closely-related species H. hecale and H. ismenius. We focus on geographic regions where the two species mimic each other, and contrast this with geographic regions where they do not mimic each other. To examine population history and patterns of gene flow, we tested and compared a four-population model accounting for linked selection. This model suggests that the two species have remained isolated for a large part of their history, yet with a small amount of gene exchange. Accordingly, signatures of genomic introgression were small except at a major wing pattern allele and chemosensing genes, and stronger in the mimetic populations compared to non-mimetic populations. Behavioural assays confirm that visual confusion exists but that short-range cues determine strong sexual isolation. Tests for chemical differentiation between species identified major differences in putative pheromones which likely mediate mate choice and the maintenance of species differences.
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Affiliation(s)
- Quentin Rougemont
- Centre d'Ecologie Fonctionnelle et Evolutive, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Bárbara Huber
- Institut de Systématique, Evolution et Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
- Smithsonian Tropical Research Institute, Balboa, Panama
- Instituto de Ciencias Ambientales y Ecológicas (ICAE), Universidad de Los Andes, Mérida, Venezuela
| | - Simon Martin
- Department of Zoology, University of Cambridge, United Kingdom
| | - Annabel Whibley
- Institut de Systématique, Evolution et Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
| | - Catalina Estrada
- Smithsonian Tropical Research Institute, Balboa, Panama
- Department of Life Sciences, Imperial College London, Silwood Park, London, UK
| | - Darha Solano
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Robert Orpet
- Smithsonian Tropical Research Institute, Balboa, Panama
- Department of Entomology, Washington State University, Wenatchee, Washington, USA
| | | | - Brigitte Frérot
- INRAE, CNRS, IRD, UPEC, Sorbonne Université, Institute of Ecology and Environmental Sciences of Paris, Université de Paris, 78000 Versailles, France
| | - Mathieu Joron
- Centre d'Ecologie Fonctionnelle et Evolutive, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Institut de Systématique, Evolution et Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
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Nabity PD, Orpet R, Miresmailli S, Berenbaum MR, DeLucia EH. Silica and nitrogen modulate physical defense against chewing insect herbivores in bioenergy crops Miscanthus x Giganteus and Panicum virgatum (Poaceae). J Econ Entomol 2012; 105:878-83. [PMID: 22812125 DOI: 10.1603/ec11424] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Feedstock crops selected for bioenergy production to date are almost exclusively perennial grasses because of favorable physiological traits that enhance growth, water use, and nutrient assimilation efficiency. Grasses, however, tend to rely primarily on physical defenses, such as silica, to deter herbivores. Silica impedes processing of feedstocks and introduces a trade-off between managing for cost efficiency (i.e., yield) and plant defenses. To test how silica modulates herbivory in two of the most preferred feedstock crops for production across the central United States, miscanthus (Miscanthus x giganteus Greef and Deuter ex Hodkinson and Renvoize) and switchgrass (Panicum virgatum L.), we examined the performance of two immature generalist insect herbivores, fall armyworm (Spodoptera frugiperda (J.E. Smith) and the American grasshopper [Schistocerca americana (Drury)], on grasses grown under silica and nitrogen amendment. Both miscanthus and switchgrass assimilated nitrogen and silica when grown in amended soil that altered the consumption and conversion efficiency of herbivores consuming leaf tissue. The magnitude of nutrient assimilation, however, depended on intrinsic plant traits. Nitrogen increased conversion efficiency for both fall armyworm and American grasshopper but increased consumption rate only for fall armyworm. Silica reduced conversion efficiency and increased consumption rate only for the American grasshopper. Because of this variability, management strategies that reduce silica or increase nitrogen content in feedstock crops to enhance yields may directly influence the ability of bioenergy grasses to deter certain generalist herbivores.
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Affiliation(s)
- P D Nabity
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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