The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations
Abstract The success rate of weed biological control programs is difficult to evaluate and the factors affecting it remain poorly understood. One aspect which is still unclear is whether releases of multiple, genetically distinct populations of a biological control agent increase the likelihood of s...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2019-03-01
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| Series: | Evolutionary Applications |
| Subjects: | |
| Online Access: | https://doi.org/10.1111/eva.12726 |
| _version_ | 1818139700187103232 |
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| author | Marianna Szűcs Patricia E. Salerno Brittany J. Teller Urs Schaffner Jeffrey L. Littlefield Ruth A. Hufbauer |
| author_facet | Marianna Szűcs Patricia E. Salerno Brittany J. Teller Urs Schaffner Jeffrey L. Littlefield Ruth A. Hufbauer |
| author_sort | Marianna Szűcs |
| collection | DOAJ |
| description | Abstract The success rate of weed biological control programs is difficult to evaluate and the factors affecting it remain poorly understood. One aspect which is still unclear is whether releases of multiple, genetically distinct populations of a biological control agent increase the likelihood of success, either by independent colonization of different environmental niches or by hybridization that may increase the agent's fitness and adaptive ability. Since hybridization is often invoked to explain the success of unintentionally introduced exotic species, hybridization among biocontrol agents may be similarly important in shaping the effectiveness of biological control programs. In this study, we first evaluated intraspecific hybridization among populations of a weed biological control agent, the ragwort flea beetle, Longitarsus jacobaeae. These insects were introduced as part of a classical biological control program from Italy and Switzerland. We genotyped 204 individuals from 15 field sites collected in northwest Montana, and an additional 52 individuals that served as references for Italian and Swiss populations. Bayesian analysis of population structure assigned seven populations as pure Swiss and one population as pure Italian, while intraspecific hybrid individuals were detected in seven populations at frequencies of 5%–69%. Subsequently, we conducted a 2‐year exclusion experiment using six sites with Swiss beetles and three with hybrid beetles to evaluate the impact of biological control. We found that biological control by Swiss beetles and by hybrid beetles is effective, increasing mortality of the target plant, Jacobaea vulgaris, by 42% and 45%, and reducing fecundity of surviving plants by 44% and 72%, respectively. Beetle densities were higher and mortality of larger plants was higher at sites with hybrids present. These results suggest that hybridization of ragwort flea beetles at high‐elevation sites may improve biological control of tansy ragwort and that intraspecific hybridization of agents could benefit biological control programs. |
| first_indexed | 2024-12-11T10:32:15Z |
| format | Article |
| id | doaj.art-3135c7b597b94228b6a69fd02cb65f5d |
| institution | Directory Open Access Journal |
| issn | 1752-4571 |
| language | English |
| last_indexed | 2024-12-11T10:32:15Z |
| publishDate | 2019-03-01 |
| publisher | Wiley |
| record_format | Article |
| series | Evolutionary Applications |
| spelling | doaj.art-3135c7b597b94228b6a69fd02cb65f5d2022-12-22T01:10:52ZengWileyEvolutionary Applications1752-45712019-03-0112347048110.1111/eva.12726The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevationsMarianna Szűcs0Patricia E. Salerno1Brittany J. Teller2Urs Schaffner3Jeffrey L. Littlefield4Ruth A. Hufbauer5Department of Entomology Michigan State University East Lansing MichiganDepartment of Biology Colorado State University Fort Collins ColoradoDepartment of Biology Pennsylvania State University State College PennsylvaniaCentre for Agriculture and Biosciences International Delémont SwitzerlandDepartment of Land Resources and Environmental Sciences Montana State University Bozeman MontanaDepartment of Bioagricultural Sciences and Pest Management Colorado State University Fort Collins ColoradoAbstract The success rate of weed biological control programs is difficult to evaluate and the factors affecting it remain poorly understood. One aspect which is still unclear is whether releases of multiple, genetically distinct populations of a biological control agent increase the likelihood of success, either by independent colonization of different environmental niches or by hybridization that may increase the agent's fitness and adaptive ability. Since hybridization is often invoked to explain the success of unintentionally introduced exotic species, hybridization among biocontrol agents may be similarly important in shaping the effectiveness of biological control programs. In this study, we first evaluated intraspecific hybridization among populations of a weed biological control agent, the ragwort flea beetle, Longitarsus jacobaeae. These insects were introduced as part of a classical biological control program from Italy and Switzerland. We genotyped 204 individuals from 15 field sites collected in northwest Montana, and an additional 52 individuals that served as references for Italian and Swiss populations. Bayesian analysis of population structure assigned seven populations as pure Swiss and one population as pure Italian, while intraspecific hybrid individuals were detected in seven populations at frequencies of 5%–69%. Subsequently, we conducted a 2‐year exclusion experiment using six sites with Swiss beetles and three with hybrid beetles to evaluate the impact of biological control. We found that biological control by Swiss beetles and by hybrid beetles is effective, increasing mortality of the target plant, Jacobaea vulgaris, by 42% and 45%, and reducing fecundity of surviving plants by 44% and 72%, respectively. Beetle densities were higher and mortality of larger plants was higher at sites with hybrids present. These results suggest that hybridization of ragwort flea beetles at high‐elevation sites may improve biological control of tansy ragwort and that intraspecific hybridization of agents could benefit biological control programs.https://doi.org/10.1111/eva.12726classical weed biological controlddRADheterosisintraspecific hybridization |
| spellingShingle | Marianna Szűcs Patricia E. Salerno Brittany J. Teller Urs Schaffner Jeffrey L. Littlefield Ruth A. Hufbauer The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations Evolutionary Applications classical weed biological control ddRAD heterosis intraspecific hybridization |
| title | The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| title_full | The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| title_fullStr | The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| title_full_unstemmed | The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| title_short | The effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| title_sort | effects of agent hybridization on the efficacy of biological control of tansy ragwort at high elevations |
| topic | classical weed biological control ddRAD heterosis intraspecific hybridization |
| url | https://doi.org/10.1111/eva.12726 |
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