Specialist Insect Herbivore and Light Availability Do Not Interact in the Evolution of an Invasive Plant

Potamogeton crispus (curlyleaf pondweed) and Myriophyllum spicatum (Eurasian watermilfoil) are widely thought to competitively displace native macrophytes in North America. However, their perceived competitive superiority has not been comprehensively evaluated. Coexistence theory suggests that invader displacement of native species through competitive exclusion is most likely where high niche overlap results in competition for limiting resources. Thus, evaluation of niche similarity can serve as a starting point for predicting the likelihood of invaders having direct competitive impacts on resident species. Across two environmental gradients structuring macrophyte communities—water depth and light availability—both P. crispus and M. spicatum are thought to occupy broad niches. For a third dimension, phenology, the annual growth cycle of M. spicatum is typical of other species, whereas the winter-ephemeral phenology of P. crispus may impart greater niche differentiation and thus lower risk of native species being competitively excluded. Using an unprecedented dataset comprising 3404 plant surveys from Minnesota collected using a common protocol, we modeled niches of 34 species using a probabilistic niche framework. Across each niche dimension, P. crispus had lower overlap with native species than did M. spicatum; this was driven in particular by its distinct phenology. These results suggest that patterns of dominance seen in P. crispus and M. spicatum have likely arisen through different mechanisms, and that direct competition with native species is less likely for P. crispus than M. spicatum. This research highlights the utility of fine-scale, abundance-based niche models for predicting invader impacts.

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Advantages of a mixed diet: feeding on several foliar age classes increases the performance of a specialist insect herbivore

Oecologia ◽

10.1007/s00442-003-1213-8 ◽

2003 ◽

Vol 135 (3) ◽

pp. 391-399 ◽

Cited By ~ 47

Author(s):

Gaétan Moreau ◽

Dan T. Quiring ◽

Eldon S. Eveleigh ◽

Éric Bauce

Keyword(s):

Insect Herbivore ◽

Mixed Diet ◽

Age Classes ◽

Specialist Insect

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Effect of hostplant genotype and predators on iridoid glycoside content of pupae of a specialist insect herbivore, Junonia coenia (Nymphalidae)

Biochemical Systematics and Ecology ◽

10.1016/s0305-1978(97)00058-6 ◽

1997 ◽

Vol 25 (7) ◽

pp. 571-580 ◽

Cited By ~ 18

Author(s):

M.Deane Bowers ◽

Nancy E. Stamp

Keyword(s):

Iridoid Glycoside ◽

Junonia Coenia ◽

Insect Herbivore ◽

Specialist Insect

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Limited natural regeneration of unique Scalesia forest following invasive plant removal in Galapagos

PLoS ONE ◽

10.1371/journal.pone.0258467 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0258467

Author(s):

Anna Walentowitz ◽

Michael Manthey ◽

María Belén Bentet Preciado ◽

Rafael Chango ◽

Christian Sevilla ◽

...

Keyword(s):

Plant Species ◽

Natural Regeneration ◽

Large Scale ◽

Invasive Plant ◽

Linear Models ◽

Light Availability ◽

Percent Cover ◽

Introduced Plants ◽

Adult Trees ◽

Sapling Survival

More than 60% of the flora of the Galapagos Islands is introduced and some of these species have become invasive, severely altering ecosystems. An example of an affected ecosystem is the Scalesia forest, originally dominated by the endemic giant daisy tree Scalesia pedunculata (Asteraceae). The remnant patches of this unique forest are increasingly being invaded by introduced plants, mainly by Rubus niveus (blackberry, Rosaceae). To help large-scale restoration of this ecologically important forest, we seek to better understand the natural regeneration of S. pedunculata after invasive plant control. We monitored naturally recruited S. pedunculata saplings and young trees over five years in an area where invasive plant species are continuously being removed by manual means. We measured survival, height and growth of S. pedunculata saplings and young trees along permanent transects. Percent cover of surrounding plant species and of canopy shade directly above each S. pedunculata individual were determined, as well as distance to the next mature S. pedunculata tree. We identified potential factors influencing initial sapling survival and growth by applying generalized linear models. Results showed a rapid growth of saplings and young trees of up to 0.45 cm per day and a high mortality rate, as is typical for pioneer species like S. pedunculata. Sapling survival, growth and mortality seemed to be influenced by light availability, surrounding vegetation and distance to the next adult S. pedunculata tree. We concluded that natural regeneration of S. pedunculata was high only five months after the last herbicide application but that 95% of these recruits had died over the 5-year period. Further studies are needed to corroborate whether the number of surviving trees is sufficient to replace the aging adult trees and this way maintain remnants of the Scalesia forest. Urgent action is needed to help improve future restoration strategies to prevent further degradation of this rapidly shrinking threatened forest ecosystem.

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Climate Change and Local Host Availability Drive the Northern Range Boundary in the Rapid Expansion of a Specialist Insect Herbivore, Papilio cresphontes

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.579230 ◽

2021 ◽

Vol 9 ◽

Author(s):

J. Keaton Wilson ◽

Nicolas Casajus ◽

Rebecca A. Hutchinson ◽

Kent P. McFarland ◽

Jeremy T. Kerr ◽

...

Keyword(s):

Data Collection ◽

Host Plant ◽

Rapid Change ◽

Rapid Expansion ◽

Insect Herbivore ◽

Specialist Herbivore ◽

Recent Emergence ◽

Specialist Insect ◽

Community Science ◽

Analytical Approaches

Species distributions, abundance, and interactions have always been influenced by human activity and are currently experiencing rapid change. Biodiversity benchmark surveys traditionally require intense human labor inputs to find, identify, and record organisms limiting the rate and impact of scientific enquiry and discovery. Recent emergence and advancement of monitoring technologies have improved biodiversity data collection to a scale and scope previously unimaginable. Community science web platforms, smartphone applications, and technology assisted identification have expedited the speed and enhanced the volume of observational data all while providing open access to these data worldwide. How to integrate and leverage the data into valuable information on how species are changing in space and time requires new best practices in computational and analytical approaches. Here we integrate data from three community science repositories to explore how a specialist herbivore distribution changes in relation to host plant distributions and other environmental factors. We generate a series of temporally explicit species distribution models to generate range predictions for a specialist insect herbivore (Papilio cresphontes) and three predominant host-plant species. We find that this insect species has experienced rapid northern range expansion, likely due to a combination of the range of its larval host plants and climate changes in winter. This case study shows rapid data collection through large scale community science endeavors can be leveraged through thoughtful data integration and transparent analytic pipelines to inform how environmental change impacts where species are and their interactions for a more cost effective method of biodiversity benchmarking.

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Plant defense resistance in natural enemies of a specialist insect herbivore

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1912599116 ◽

2019 ◽

Vol 116 (46) ◽

pp. 23174-23181 ◽

Cited By ~ 8

Author(s):

Xi Zhang ◽

Cong van Doan ◽

Carla C. M. Arce ◽

Lingfei Hu ◽

Sandra Gruenig ◽

...

Keyword(s):

Plant Defense ◽

Natural Enemies ◽

Entomopathogenic Nematodes ◽

Western Corn Rootworm ◽

Insect Herbivore ◽

Corn Rootworm ◽

Biological Control Agents ◽

Metabolic Resistance ◽

Evolution Of Resistance ◽

Specialist Insect

Plants defend themselves against herbivores through the production of toxic and deterrent metabolites. Adapted herbivores can tolerate and sometimes sequester these metabolites, allowing them to feed on defended plants and become toxic to their own enemies. Can herbivore natural enemies overcome sequestered plant defense metabolites to prey on adapted herbivores? To address this question, we studied how entomopathogenic nematodes cope with benzoxazinoid defense metabolites that are produced by grasses and sequestered by a specialist maize herbivore, the western corn rootworm. We find that nematodes from US maize fields in regions in which the western corn rootworm was present over the last 50 y are behaviorally and metabolically resistant to sequestered benzoxazinoids and more infective toward the western corn rootworm than nematodes from other parts of the world. Exposure of a benzoxazinoid-susceptible nematode strain to the western corn rootworm for 5 generations results in higher behavioral and metabolic resistance and benzoxazinoid-dependent infectivity toward the western corn rootworm. Thus, herbivores that are exposed to a plant defense sequestering herbivore can evolve both behavioral and metabolic resistance to plant defense metabolites, and these traits are associated with higher infectivity toward a defense sequestering herbivore. We conclude that plant defense metabolites that are transferred through adapted herbivores may result in the evolution of resistance in herbivore natural enemies. Our study also identifies plant defense resistance as a potential target for the improvement of biological control agents.

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