Browsing by Author "Endriss, Stacy B."

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    From ecological menace to roadside attraction: 28 years of evidence support successful biocontrol of purple loosestrife
    Blossey, Bernd; Nuzzo, Victoria; Endriss, Stacy B. (Wiley, 2024-12-03)
    Introduction and spread of non-native plants provide ecologists and evolutionary biologists with abundant scientific opportunities. However, land managers charged with preventing ecological impacts face financial and logistical challenges to reduce threats by introduced species. The available toolbox (chemical, mechanical, or biological) is also rather limited. Failure to permanently suppress introduced species by mechanical and chemical treatments may result in biocontrol programs using host-specific insect herbivores. Regardless of the chosen method, long-term assessment of management outcomes on both the target species and associated biota should be an essential component of management programs. However, data to assess whether management results in desirable outcomes beyond short-term reductions of the target plant are limited. Here, we use implementation of a biocontrol program targeting a widespread wetland invader, Lythrum salicaria (purple loosestrife), in North America to track outcomes on the target plant over more than two decades in New York State. After extensive testing, two leaf-feeding beetles (Galerucella calmariensis and Galerucella pusilla; hereafter “Galerucella”), a root-feeding weevil (Hylobius transversovittatus) and a flower-feeding weevil (Nanophyes marmoratus), were approved for field releases. We used a standardized monitoring protocol to record insect abundance and L. salicaria stem densities and heights in 1-m2 permanent quadrats at 33 different wetlands and followed sites for up to 28 years. As part of this long-term monitoring, in 20 of these wetlands, we established a factorial experiment releasing either no insects (control), only root feeders, only leaf beetles, or root and leaf feeders. We documented reduced L. salicaria occupancy and stem densities following insect releases over time, irrespective of site-specific differences in starting plant communities or L. salicaria abundance. We could not complete our factorial experiment because dispersal of leaf beetles to root-feeder-only and control sites within 5 years invalidated our experimental controls. Our data show that it took time for significant changes to occur, and short-term studies may provide misleading results, as L. salicaria stem densities initially increased before significantly decreasing. Several decades after insect releases, prerelease predictions of significant purple loosestrife declines have been confirmed.
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    Success takes time: History and current status of biological control of purple loosestrife in the United States
    Endriss, Stacy B.; Nuzzo, Victoria; Blossey, Bernd (2022)
    Purple loosestrife (Lythrum salicaria, Lythraceae) is a long-lived forb that has negatively affected North American wetlands for decades. Following the introduction of purple loosestrife from Eurasia in the early 1800s, populations gradually spread across North America, eventually leading to the decline of many native birds, plants, and amphibians. Land managers recognized the widespread ecological harm caused by purple loosestrife and called for sustainable control methods, realizing that traditional methods such as chemical treatments had failed to produce desirable outcomes. In response, research to assess biological control options for purple loosestrife began in 1986 in Europe. This biological control program represented one of the first times a plant was targeted for biological control because of its harm to flora and fauna rather than because of its negative impacts to agriculture. This work led to the release of four host-specific insects: two leaf-feeding beetles (Galerucella calmariensis and Galerucella pusilla; both Coleoptera: Chrysomelidae) and a root-feeding weevil (Hylobius transversovittatus; Coleoptera: Curculionidae) in 1992, followed in 1994 by a flower-feeding weevil (Nanophyes marmoratus; Coleoptera: Curculionidae). The Galerucella leaf-feeding beetles now appear to be widely established and abundant. Data on the abundance and distribution of the root-feeding and flowering-feeding weevils remain sparse. The effect of these insects may vary from site to site, but in many regions across North America, such as the Pacific Northwest, the Great Lakes Region, and the Northeast, biological control of purple loosestrife is now highly effective and economical. For example, long-term data collected from New York document that these insects reduce the density, height, and flower production of purple loosestrife, which in turn allows an increase in native plant diversity. This is the ultimate goal of weed management. Many biological control success stories are anecdotal, and purple loosestrife is one of the first examples for which we have strong evidence that control of invasive plants by insects can result in native plant recovery.