skip to main content


Title: Biological Control of Pest Non-Marine Molluscs: A Pacific Perspective on Risks to Non-Target Organisms
Classic biological control of pest non-marine molluscs has a long history of disastrous outcomes, and despite claims to the contrary, few advances have been made to ensure that contemporary biocontrol efforts targeting molluscs are safe and effective. For more than half a century, malacologists have warned of the dangers in applying practices developed in the field of insect biological control, where biocontrol agents are often highly host-specific, to the use of generalist predators and parasites against non-marine mollusc pests. Unfortunately, many of the lessons that should have been learned from these failed biocontrol programs have not been rigorously applied to contemporary efforts. Here, we briefly review the failures of past non-marine mollusc biocontrol efforts in the Pacific islands and their adverse environmental impacts that continue to reverberate across ecosystems. We highlight the fact that none of these past programs has ever been demonstrated to be effective against targeted species, and at least two (the snails Euglandina spp. and the flatworm Platydemus manokwari) are implicated in the extinction of hundreds of snail species endemic to Pacific islands. We also highlight other recent efforts, including the proposed use of sarcophagid flies and nematodes in the genus Phasmarhabditis, that clearly illustrate the false claims that past bad practices are not being repeated. We are not making the claim that biocontrol programs can never be safe and effective. Instead, we hope that in highlighting the need for robust controls, clear and measurable definitions of success, and a broader understanding of ecosystem level interactions within a rigorous scientific framework are all necessary before claims of success can be made by biocontrol advocates. Without such amendments to contemporary biocontrol programs, it will be impossible to avoid repeating the failures of non-marine mollusc biocontrol programs to date.  more » « less
Award ID(s):
1656254 1656231 1837849 1902328
NSF-PAR ID:
10282013
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Insects
Volume:
12
Issue:
7
ISSN:
2075-4450
Page Range / eLocation ID:
583
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Abstract Since 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flatworms were widely introduced in attempted biological control of giant African snails ( Lissachatina fulica ) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L. fulica and native snails. Since 1993 there have been unofficial releases of Euglandina within island groups. Only three official P. manokwari releases took place, but new populations are being recorded at an increasing rate, probably because of accidental introduction. Claims that these predators controlled L. fulica cannot be substantiated; in some cases pest snail declines coincided with predator arrival but concomitant declines occurred elsewhere in the absence of the predator and the declines in some cases were only temporary. In the Hawaiian Islands, although there had been some earlier declines of native snails, the Euglandina impacts on native snails are clear with rapid decline of many endemic Hawaiian Achatinellinae following predator arrival. In the Society Islands, Partulidae tree snail populations remained stable until Euglandina introduction, when declines were extremely rapid with an exact correspondence between predator arrival and tree snail decline. Platydemus manokwari invasion coincides with native snail declines on some islands, notably the Ogasawara Islands of Japan, and its invasion of Florida has led to mass mortality of Liguus spp. tree snails. We conclude that Euglandina and P. manokwari are not effective biocontrol agents, but do have major negative effects on native snail faunas. These predatory snails and flatworms are generalist predators and as such are not suitable for biological control. 
    more » « less
  2. Abstract

    Non‐native freshwater snails can play important roles as consumers, hosts, and prey. Despite their potential ecological importance, global patterns in non‐native snail taxonomy, geography, and ecology have not been documented. Our objectives were to use a semi‐quantitative systematic review to describe non‐native freshwater snail global diversity, distribution, mechanisms of introduction, and interactions with natural enemies, including parasites and predators.

    Based on 506 relevant publications, we recorded 95 non‐native freshwater snail species from 16 families. Six taxonomic families, and pulmonate snails as a group, were over‐represented relative to the number of species expected by chance. Eight snail species represented 63% of the research records. A few snail taxa (15%) were widespread global invaders, reported from four or more continents, while most invasions were limited to a single continent. Australia and the Pacific Islands were the largest ‘sink’ for non‐native snails, with the greatest difference in the number of non‐native taxa relative to native taxa that had spread to other continents.

    Aquarium hobby sales were implicated as the most common mechanism of introduction (41% of species), followed by “hitchhiking” on aquatic vegetation, human consumption, use for biocontrol, transportation in canals, commercial shipping, and outdoor recreation. A search of internet sales posts indicated that four of the six over‐represented snail families were readily available for purchase online.

    Non‐native snails hosted parasites of wildlife, livestock, and human health importance, yet on average had 80% lower parasite richness in their non‐native compared to native range. At least 65 taxa were documented as consumers of non‐native snails, including native predators of conservation concern. These findings suggest that non‐native snails often are released from parasitism, but may commonly experience biotic resistance from predators.

    Our synthesis emphasizes the relatively high diversity of non‐native snails, but the disproportionate role of a few taxonomic groups in driving ecological, economic, and public health challenges. Moving forward, it will be important to limit new snail introductions through policy, education, and monitoring, particularly as the effective control of established snail invasions remains challenging in most ecosystems.

     
    more » « less
  3. BACKGROUND The past decade has witnessed considerable progress toward the creation of new quantum technologies. Substantial advances in present leading qubit technologies, which are based on superconductors, semiconductors, trapped ions, or neutral atoms, will undoubtedly be made in the years ahead. Beyond these present technologies, there exist blueprints for topological qubits, which leverage fundamentally different physics for improved qubit performance. These qubits exploit the fact that quasiparticles of topological quantum states allow quantum information to be encoded and processed in a nonlocal manner, providing inherent protection against decoherence and potentially overcoming a major challenge of the present generation of qubits. Although still far from being experimentally realized, the potential benefits of this approach are evident. The inherent protection against decoherence implies better scalability, promising a considerable reduction in the number of qubits needed for error correction. Transcending possible technological applications, the underlying physics is rife with exciting concepts and challenges, including topological superconductors, non-abelian anyons such as Majorana zero modes (MZMs), and non-abelian quantum statistics.­­ ADVANCES In a wide-ranging and ongoing effort, numerous potential material platforms are being explored that may realize the required topological quantum states. Non-abelian anyons were first predicted as quasiparticles of topological states known as fractional quantum Hall states, which are formed when electrons move in a plane subject to a strong perpendicular magnetic field. The prediction that hybrid materials that combine topological insulators and conventional superconductors can support localized MZMs, the simplest type of non-abelian anyon, brought entirely new material platforms into view. These include, among others, semiconductor-superconductor hybrids, magnetic adatoms on superconducting substrates, and Fe-based superconductors. One-dimensional systems are playing a particularly prominent role, with blueprints for quantum information applications being most developed for hybrid semiconductor-superconductor systems. There have been numerous attempts to observe non-abelian anyons in the laboratory. Several experimental efforts observed signatures that are consistent with some of the theoretical predictions for MZMs. A few extensively studied platforms were subjected to intense scrutiny and in-depth analyses of alternative interpretations, revealing a more complex reality than anticipated, with multiple possible interpretations of the data. Because advances in our understanding of a physical system often rely on discrepancies between experiment and theory, this has already led to an improved understanding of Majorana signatures; however, our ability to detect and manipulate non-abelian anyons such as MZMs remains in its infancy. Future work can build on improved materials in some of the existing platforms but may also exploit new materials such as van der Waals heterostructures, including twisted layers, which promise many new options for engineering topological phases of matter. OUTLOOK Experimentally establishing the existence of non-abelian anyons constitutes an outstandingly worthwhile goal, not only from the point of view of fundamental physics but also because of their potential applications. Future progress will be accelerated if claims of Majorana discoveries are based on experimental tests that go substantially beyond indicators such as zero-bias peaks that, at best, suggest consistency with a Majorana interpretation. It will be equally important that these discoveries build on an excellent understanding of the underlying material systems. Most likely, further material improvements of existing platforms and the exploration of new material platforms will both be important avenues for progress toward obtaining solid evidence for MZMs. Once that has been achieved, we can hope to explore—and harness—the fascinating physics of non-abelian anyons such as the topologically protected ground state manifold and non-abelian statistics. Proposed topological platforms. (Left) Proposed state of electrons in a high magnetic field (even-denominator fractional quantum Hall states) are predicted to host Majorana quasiparticles. (Right) Hybrid structures of superconductors and other materials have also been proposed to host such quasiparticles and can be tailored to create topological quantum bits based on Majoranas. 
    more » « less
  4. null (Ed.)
    A major barrier to increasing the percentage of underrepresented minority (URM) faculty in STEM fields is the small number of URM applicants for academic positions. One factor contributing to this situation is that the two-year attrition rate of URM doctoral students is nearly 50%, substantially greater than the rate for non-URM students at most institutions. Many efforts have been made to decrease the attrition, most involving direct work with doctoral students and others concentrating on institutional changes such naming a high-level administrator to coordinate recruitment and retention efforts. Often lacking in these efforts are attempts to change faculty attitudes and practices that negatively affect student retention. Three public universities including one HBCU are currently carrying out a five-year project to develop and pilot-test a department-level process to fill this gap. Why the focus on the department level? Since URM students spend most of their time in their departments as they take classes, attend seminars, conduct research, and interact informally with department faculty, staff, and other graduate students, the climate they experience and the support they receive can have a major impact on their success. In addition, changes in a department can last well beyond the end of a grant. When interventions address students directly, once they graduate there may be no lasting change in the department. When faculty attitudes and mentoring practices change, on the other hand, the changes may last and continue to help students succeed long after the grant expires. The project seeks to help department faculty increase their understanding of the issues facing underrepresented minorities in doctoral programs, identify and remedy the departmental practices that may be hindering URM student success, and examine and improve their own mentoring practices. In the project, six cohorts of faculty members and both URM and non-URM doctoral students—two cohorts at each participating university—will be assembled and surveyed. The faculty members will be asked how their departments address recruitment and retention of URM students, how they personally support and mentor their URM students, and how welcoming and supportive of URM students they perceive their department to be. The students will be asked to express their level of satisfaction with their coursework and their relationships with faculty and other graduate students, describe the learning opportunities and mentoring they have received, and discuss how welcoming and supportive of URM students their departments have been. To initiate the gathering of baseline information, the first cohort—79 faculty members, 16 URM students, and 94 non-URM students from six STEM departments at one of the universities—was surveyed. This presentation will report and discuss the results. 
    more » « less
  5. null (Ed.)
    A major barrier to increasing the percentage of underrepresented minority (URM) faculty in STEM fields is the small number of URM applicants for academic positions. One factor contributing to this situation is that the two-year attrition rate of URM doctoral students is nearly 50%, substantially greater than the rate for non-URM students at most institutions. Many efforts have been made to decrease the attrition, most involving direct work with doctoral students and others concentrating on institutional changes such naming a high-level administrator to coordinate recruitment and retention efforts. Often lacking in these efforts are attempts to change faculty attitudes and practices that negatively affect student retention. Three public universities including one HBCU are currently carrying out a five-year project to develop and pilot-test a department-level process to fill this gap. Why the focus on the department level? Since URM students spend most of their time in their departments as they take classes, attend seminars, conduct research, and interact informally with department faculty, staff, and other graduate students, the climate they experience and the support they receive can have a major impact on their success. In addition, changes in a department can last well beyond the end of a grant. When interventions address students directly, once they graduate there may be no lasting change in the department. When faculty attitudes and mentoring practices change, on the other hand, the changes may last and continue to help students succeed long after the grant expires. The project seeks to help department faculty increase their understanding of the issues facing underrepresented minorities in doctoral programs, identify and remedy the departmental practices that may be hindering URM student success, and examine and improve their own mentoring practices. In the project, six cohorts of faculty members and both URM and non-URM doctoral students—two cohorts at each participating university—will be assembled and surveyed. The faculty members will be asked how their departments address recruitment and retention of URM students, how they personally support and mentor their URM students, and how welcoming and supportive of URM students they perceive their department to be. The students will be asked to express their level of satisfaction with their coursework and their relationships with faculty and other graduate students, describe the learning opportunities and mentoring they have received, and discuss how welcoming and supportive of URM students their departments have been. To initiate the gathering of baseline information, the first cohort—79 faculty members, 16 URM students, and 94 non-URM students from six STEM departments at one of the universities—was surveyed. This presentation will report and discuss the results. 
    more » « less