The introduction and establishment of Pseudacteon obtusus Borgmeier (Diptera: Phoridae) into the ... more The introduction and establishment of Pseudacteon obtusus Borgmeier (Diptera: Phoridae) into the United States is an important milestone in the effort to introduce a suite of parasitoids and pathogens as prospective biocontrol agents of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae). P. obtusus is the fourth species of phorid fly to be established in the US and
A new microsporidian genus and species, Myrmecomorba nylanderiae, is described from North America... more A new microsporidian genus and species, Myrmecomorba nylanderiae, is described from North American populations of the tawny crazy ant, Nylanderia fulva. This new species was found to be heterosporous producing several types of binucleate spores in both larval and adult stages and an abortive octosporoblastic sporogony in adult ants. While microsporidia are widespread arthropod parasites, this description represents only the fifth species described from an ant host. Molecular analysis indicated that this new taxon is phylogenetically closely allied to the microsporidian family Caudosporidae, a group known to parasitize aquatic black fly larvae. We report the presence of 3 spore types (Type 1 DK, Type 2 DK, and octospores) with infections found in all stages of host development and reproductive castes. This report documents the first pathogen infecting Nylanderia fulva, an invasive ant of considerable economic and ecological consequence.
Proceedings of the National Academy of Sciences of the United States of America, Mar 28, 2022
SignificanceInvasive social insects are among the most damaging of invasive organisms and have pr... more SignificanceInvasive social insects are among the most damaging of invasive organisms and have proved universally intractable to biological control. Despite this, populations of some invasive social insects collapse from unknown causes. We report long-term studies demonstrating that infection by a microsporidian pathogen causes populations of a globally significant invasive ant to collapse to local extinction, providing a mechanistic understanding of a pervasive phenomenon in biological invasions: the collapse of established populations from endogenous factors. We apply this knowledge and successfully eliminate two large, introduced populations of these ants. More broadly, microsporidian pathogens should be evaluated for control of other supercolonial invasive social insects. Diagnosing the cause of unanticipated population collapse in invasive organisms can lead to applied solutions.
The once-extensive tallgrass prairie community of North America has been reduced to small remnant... more The once-extensive tallgrass prairie community of North America has been reduced to small remnants, many of which are surrounded by intensive corn (Zea mays) agriculture. We investigated adult cornrootworm beetles (Chrysomelidae: Diabrotica spp.), important pests of corn, on sunflowers (Asteraceae: Helianthus spp.) in prairie remnants in southeast Minnesota. Large numbers of beetles invaded the prairie from surrounding corn fields in late summer. D. barberi and D. virgifera were captured on sticky traps in all locations in the prairie, but abundance was much greater near the edge adjacent to corn. We observed D, barberi (but not D. virgifera) feeding extensively on sunflower pollen and occasionally on other flower parts, such as petak. Sunflowers located nearer corn fields sustained morefloral damage than those farther from o m. To determine the effect of beetle &mage on seed set, we enclosed sunflower heads in bags with either zero, two, or four D. barberi adults. Seed set was reduced in heads enclosed with D. barberi Thus, this agriculturalpest may interfere with the successful reproduction of sunflowers and possibly otherprairie composites thatflower in late summer. Given the small size of mostprairie remnants and the abundance of thisflowerrfeeding beetle in landscapes dominated by corn agriculture, D. barberi may affect the sustainability ofprairie plantpopulations. Un Efecto de Borde Causado por Escarabajos Adultos sobre Girasoles en Remanentes de Pastizales de Praderas Resumen: La que fuera alguna vez una comunidad de pastizales altos de pradera de Norteam6rica ha sido reducida a remanentespequefios, muchos de 10s cuales estan rodeados de tierras de cultivo intensivo de maiz (Zea mays). Znvestigamos 10s adultos del escarabajo (Chrysomelidae: Diabrotica spp.), una plaga importante del maiz, en los girasoles (Asteraceae: Helianthus spp.) en remanentes de pradera del sureste de Minesota. Grandes cantidades de escarabajos provenientes de los cultivos de maiz adyacentes invadieron la pradera hacia finales del verano. D. barberi y D. virgifera fueron capturados en trampas pegajosas en todas las localidades de la pradera, pero la abundancia fue mucho mayor cerca del borde adyacente a los cultivos de maiz. Observamos que D, barberi (pero no D. virgifera) se alimentaron extensivamente delpolen de girasoles y ocasionalmente en otraspartes de lasflores, como son losp6talos. Los girasoles ubicados cerca de los campos de maizpresentaron u n mayor dafio floral que aquellos alejados del maiz. Para detemzinar el efecto del dafio de 10s escarabajos en las semillas, encerramos cabezas de girasol en bolsas que contenian cero, dos o cuatro D. barberi adultos. Los juegos de semillas fueron reducidos en las cabezas encerradas con D. barberi Por lo tanto, esta plaga agricola puede interferir con la reproduccion exitosa de los girasoles y posiblemente de otros elementos de las praderas que florean hacia el final del verano. Dado elpequefio tamafio de la mayoria de 10s remanentes de la pradera y a la abundancia de estos escarabajos que se alimentan de flores en paisajes dominados por el cultivo de maiz, D. barberi podria afectar la sostenibilidad de las poblaciones de plantas de la pradera.
Flooding impacts ground nesting ant colonies by destroying the infrastructure housing and organiz... more Flooding impacts ground nesting ant colonies by destroying the infrastructure housing and organizing societal function. Here, we report the convergent evolution in distantly related ant species of a behavioral trait that minimizes costs of flooding: the construction of earthen levees around nest entrances. In a South American floodplain ecosystem, we observed five ant species constructing prominent earthen berms encircling nest entrances shortly after large rainfall events. In four of these species, experimental flooding of nests demonstrated that earthen berms sufficed to prevent floodwaters from entering the below ground portions of the nest. Additional manipulations revealed that levee breaching caused, pronounced, and extended reductions in food collection for two distantly related species. Foraging was preempted by the allocation of workers to repair the internal structure of the nest. These findings represent convergent evolution of a functionally important nest construction behavior in response to comparable selective forces.
Since the first report on introductions to Texas of Pseudacteon decapitatingflies, a variety of p... more Since the first report on introductions to Texas of Pseudacteon decapitatingflies, a variety of participants have released flies in a range of sites. The expansions of Pseudacteon populations have been systematically and widely monitored. Before 2002, the widely released initial species P. tricuspis Borgmeier did not become established. Severe drought in 1996-2001 and host-sizedependent sex ratio were proposed constraints in establishing this species. In recentyears, however, these limitations have been lifted in some areas by favorable weather,irrigation of release sites, and/or by use of a smaller Pseudacteon species, P. curvatus Borgmeier, not reliant on larger fire ant workers to produce females. Beginning in 2002, the USDA-APHIS collaboration with USDA-ARS and Texas Cooperative Extension programs began to supplement release sites in Texas beyondthose initiated by the University of Texas, Austin phorid flyproject. In 2005, privatecitizens began to participate in the spread of Pseudacteon to new sites. By fall 2006, P. tricuspis, expanding from releases between 1999 and 2001, was found on more than 3 million hectares of Central and Coastal Texas, while P. curvatus, withits later start, is only now beginning to expand at some sites. Pseudacteon that established more easily in mesic and moderate climates has difficulty surviving unfavorableweather in South Texas. However, two sites where flies "failed" to becomeestablished were revealed to be false negatives after the record rains of summer2007. Starting in late 2006, the first releases of P. obtusus Borgmeier in NorthAmerica established, and three to five additional species are being released. Resumen. Desde el primer reporte del estado de las introducciones en Texas de la mosca decapitadota Pseudacteon ha habido avances significativos en las actividadesde liberaci6n por una gran variedad de participantes. Un monitoreo sistematicode la expansi6n de las poblaciones de Pseudacteon se encuentra en
Know Your Enemy Fire ants accidentally introduced to North America from their native range in Arg... more Know Your Enemy Fire ants accidentally introduced to North America from their native range in Argentina have been hugely invasive and difficult to eradicate and caused both environmental and economic damage. Recently, another accidentally introduced Argentine ant, the tawny crazy ant, appears to be displacing the fire ants. How? LeBrun et al. (p. 1014 , published online 13 February; see the Perspective by Kaspari and Weiser ) show that tawny crazy ants have a chemical and behavioral response to the toxic bite of fire ants that vastly reduces their mortality during confrontations and that allows the tawny crazy ants to outcompete their rivals.
The microsporidian pathogen Myrmecomorba nylanderiae Plowes et al. infects introduced tawny crazy... more The microsporidian pathogen Myrmecomorba nylanderiae Plowes et al. infects introduced tawny crazy ants (Nylanderia fulva (Mayr)), and constitutes one of the first natural enemies known to attack this invasive ant. We assess how infection is transmitted within colonies and how infection impacts N. fulva colony fragment growth under carbohydrate‐deficient and carbohydrate‐sufficient dietary conditions. Carbohydrate scarcity is a common source of stress for ant colonies. Infected workers efficiently pass infection to developing larvae but all other potential pathways for within colony transmission are rare or non‐viable. For unknown reasons, queens within infected colony fragments are generally uninfected, limiting the role of transovarial transmission in intracolony transmission. In the laboratory, infection by M. nylanderiae primarily impacts the growth of N. fulva colonies by reducing pupal production. Colony growth showed a substantially greater impact under carbohydrate‐deficient conditions implying that the effect of the pathogen may depend on seasonally variable carbohydrate availability. In the colony growth assay, worker mortality did not differ with infection status under either nutrient regime. However, in a longer, direct test of survivorship, infected worker survivorship was significantly lower. Recently, some established N. fulva populations with high prevalence of M. nylanderiae infection have declined precipitously, though it is unknown if M. nylanderiae is a causative agent in these declines. The combination of chronic impacts, presence in North America, and potential association with population declines makes M. nylanderiae a promising prospect for the biological control of N. fulva.
Combating invasive species requires a detailed, mechanistic understanding of the manner and speed... more Combating invasive species requires a detailed, mechanistic understanding of the manner and speed with which organisms expand their ranges. Biological control efforts provide an opportunity to study the process of species invasions and range expansions under known initial conditions. This study examines the rate, pattern and mechanisms of spread for two populations of the biological control agent Pseudacteon tricuspis, phorid-fly
Summary1. Habitat disturbance and species invasions interact in natural systems, making it diffic... more Summary1. Habitat disturbance and species invasions interact in natural systems, making it difficult to isolate the primary cause of ecosystem degradation. A general understanding requires case studies of how disturbance and invasion interact across a variety of ecosystem – invasive species combinations.2. Dramatic losses in ant diversity followed the invasion of central Texas by red imported fire ants (Solenopsis invicta). However, recent manipulative studies in Florida revealed no effect on ant diversity following the removal of S. invicta from a disturbed pasture habitat, but moderate loss of diversity associated with their introduction into undisturbed habitat and no invasion occurred without disturbance. Thus, the importance of S. invicta in driving diversity loss and its ability to invade undisturbed systems is unresolved.3. We examine the distribution and abundance of a large monogyne S. invicta population and its association with the co‐occurring ant assemblage at a site in south Texas close to the aridity tolerance limit of S. invicta.4. We document that moisture modulates S. invicta densities. Further, soil disturbing habitat manipulations greatly increase S. invicta population densities. However, S. invicta penetrates all habitats regardless of soil disturbance history. In contrast, controlled burns depress S. invicta densities.5. In habitats where S. invicta is prevalent, it completely replaces native fire ants. However, S. invicta impacts native ants as a whole less strongly. Intriguingly, native ants responded distinctly to S. invicta in different environments. In wet, undisturbed environments, high S. invicta abundance disrupts the spatial structure of the ant assemblage by increasing clumping and is associated with reduced species density, while in dry‐disturbed habitats, sites with high S. invicta abundance possess high numbers of native species. Analyses of co‐occurrence indicate that reduced species density in wet‐undisturbed sites arises from negative species interactions between native ants and S. invicta. However, these same data suggest that the high native species density of abundant S. invicta sites in dry‐disturbed environments does not result from facilitation.6. Monogyne S. invicta populations play different roles in different environments, driving ant diversity loss in some, but being largely symptomatic of habitat disturbance in others.
Species abundances in natural systems are usually close to some equilibrium, making mechanisms th... more Species abundances in natural systems are usually close to some equilibrium, making mechanisms that maintain or prevent species coexistence difficult to discern. Biological control projects provide an opportunity to observe systems transition between equilibriums as a result of the influence of the newly introduced species. In the southeastern United States and Texas, species of phorid fly parasitoids are being sequentially introduced as control agents for imported fire ants. The first two species introduced, Pseudacteon tricuspis and P. curvatus, partition the host niche based upon body size and co‐exist broadly in their native range in Argentina, indicating they would form a co‐existing and complementary suite of parasitoids in North America. This study examines the interaction between these parasitoids at multiple temporal and spatial scales. Surprisingly, data at all scales reveal that as P. curvatus establishes at a site it competitively displaces P. tricuspis. However, the speed of this reduction appears to differ between ecoregions, suggesting that the rate of displacement depends on environment. At the site where P. curvatus has been established the longest, this population interaction approaches complete displacement. Tests of potential mechanisms causing this displacement reveal that direct competition for host workers alters the operational sex ratio of the P. tricuspis population, but the strength of this effect is insufficient to explain the displacement. Experiments reveal the operation of a strong, indirect effect whereby locally common species preempt reproductive opportunities from rarer species by inducing host behavioral defenses. Finally, a re‐examination of published data from their native range reveals that a previously overlooked negative relationship between the densities of these two species also exists there, suggesting that the same processes as those reported here also operate in South America.
... Am. Nat. 107: 737-760. Colwell, RK 1979. The geographical ecology of hum-mingbird flower mite... more ... Am. Nat. 107: 737-760. Colwell, RK 1979. The geographical ecology of hum-mingbird flower mites in relation to their host plants and carriers. In: JG Rodriguez, (Ed.). Recent ad-vances in acarology, Volume II, pp. 461-468. Aca-demic Press, New York. Colwell, RK 1986a. ...
Abignano, Giuseppina Ablin, Jacob Abou-Raya, Suzan Abrahamyan, Lusine Abu-Shakra, M. Mahmoud Abud... more Abignano, Giuseppina Ablin, Jacob Abou-Raya, Suzan Abrahamyan, Lusine Abu-Shakra, M. Mahmoud Abud-Mendoza, Carlos Ackerman, Ilana Adams, Jo Aeberli, Daniel Agarwal, Parul Ahedi, Harbeer Aitken, Dawn Ajeganova, Sofia Akai, Masami Akamatsu, Yasushi Akikusa, Jonathan Al-Mayouf, Sulaiman Alarc on, Graciela Albano-Aluquin, Shirley Albert, Daniel Albrecht, Katinka Alburquerque-Send ın, Francisco Aletaha, Daniel Alevizos, Ilias Ali, Shabana Alizai, Hamza Allanore, Yannick Allen, Kelli Almeida, Gustavo Alnaqbi, Khalid Alten, Rieke Alway, Stephen Ambrose, Nicola Amin, Shreyasee Amorim, Anita Amris, Kirstine An, JaeJin Anand, Vibha Anderson, Joel Anderson, Ronald J. Andr es, Mariano Andrews, James Angst, Felix Annapureddy, Narender Antivalle, Marco Antony, Benny Apostolopoulos, Diane Appenzeller, Simone Arima, Kazuhiko Aringer, Martin Arkema, Elizabeth Arnold, John Asanuma, Yu Asay, Jessica Askanase, Anca Askling, Johan Aslam, Fawad Assassi, Shervin Avina-Zubieta, J. Antonio Avouac, Jerome Bachmeyer, Claude Backhouse, Michael Backman, Catherine Badlissi, Fadi Baer, Alan Baker, Joshua Baker, Kenneth Baker, Nancy Baldini, Chiara Bannuru, Raveendhara Baraliakos, Xenofon Barbhaiya, Medha Barbour, Kamil Barker, Karen Barland, Peter Barnabe, Cheryl Barnado, April Baron, Murray Bartels, Christie Bartley, Emily Barton-Ellis, Carol Barton, Jennifer Basu, Neil Bathon, Joan Bearne, Lindsay Beasley, Marcus Beaton, Cleopatra Becker, Mara Bejarano, Victoria Benseler, Susanne Berard, Roberta Bergman, Martin Bergsten, Ulrika Bergstra, Sytske Anne Bermas, Bonnie Bernatsky, Sasha Berner, Jon Bertoli, Ana Beukelman, Timothy Bhutani, Gita Bieler, Theresa Bili, Androniki Bindawas, Saad Birmingham, Trevor Bjornsson, Johannes Blalock, Susan Bolen, Julie Bolster, Marcy Boneparth, Alexis Boonen, Annelies Booth, Sarah Borba, Eduardo Borenstein, David Bove, Allyn Bowen, Catherine Bowman, Simon J. Boyer, Katherine Bradley, Laurence Brady, Teresa Brasington, Richard Braun, Juergen Bremander, Ann Brennan-Olsen, Sharon Brenton-Rule, Angela Bridges, Alan Brito-Zeron, Pilar
The data file has 6 spreadsheets. Acido. Groom. - Sinvicta venom: For methods see - Acidopore gro... more The data file has 6 spreadsheets. Acido. Groom. - Sinvicta venom: For methods see - Acidopore grooming response - S. invicta venom. Acido. Groom. - other sp venom: For methods see - Acidopore grooming response - other venoms Detox. Capacity CO2 Anesthetiz.: For methods see - Detoxification capacity assay – S. invicta venom Detox Capacity Acidopor. Sealed: For methods see - Detoxification capacity assay – S. invicta venom Acid. Groom. S.A. Vid. Crufipes: For methods see - Video Analysis - South American Interactions Acid. Groom. S.A. Vid. Nfulva: For methods see - Video Analysis - South American Interaction
Biological invasions represent communities in flux. Although stasis is never the rule in nature, ... more Biological invasions represent communities in flux. Although stasis is never the rule in nature, biological interactions in communities usually occur within a framework of shared ecological and evolutionary history. Consequently, biological invasions represent unique opportunities to study dynamics that can otherwise be difficult to observe (Elton 1958). Invasive ants are excellent organisms with which to pursue this goal, in part because ants as a group play a variety of important ecological roles within biological communities (Hölldobler and Wilson 1990). Ant invasions hold much potential for improving an understanding of ecological processes in general, as well as of interactions more specific to myrmecology. For instance, the dynamics that exist during ant invasions may reveal the traits that promote behavioural or ecological dominance. Furthermore, highly successful invasive ant species are often less conspicuous in their native ranges, so identification of the factors responsi...
The introduction and establishment of Pseudacteon obtusus Borgmeier (Diptera: Phoridae) into the ... more The introduction and establishment of Pseudacteon obtusus Borgmeier (Diptera: Phoridae) into the United States is an important milestone in the effort to introduce a suite of parasitoids and pathogens as prospective biocontrol agents of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae). P. obtusus is the fourth species of phorid fly to be established in the US and
A new microsporidian genus and species, Myrmecomorba nylanderiae, is described from North America... more A new microsporidian genus and species, Myrmecomorba nylanderiae, is described from North American populations of the tawny crazy ant, Nylanderia fulva. This new species was found to be heterosporous producing several types of binucleate spores in both larval and adult stages and an abortive octosporoblastic sporogony in adult ants. While microsporidia are widespread arthropod parasites, this description represents only the fifth species described from an ant host. Molecular analysis indicated that this new taxon is phylogenetically closely allied to the microsporidian family Caudosporidae, a group known to parasitize aquatic black fly larvae. We report the presence of 3 spore types (Type 1 DK, Type 2 DK, and octospores) with infections found in all stages of host development and reproductive castes. This report documents the first pathogen infecting Nylanderia fulva, an invasive ant of considerable economic and ecological consequence.
Proceedings of the National Academy of Sciences of the United States of America, Mar 28, 2022
SignificanceInvasive social insects are among the most damaging of invasive organisms and have pr... more SignificanceInvasive social insects are among the most damaging of invasive organisms and have proved universally intractable to biological control. Despite this, populations of some invasive social insects collapse from unknown causes. We report long-term studies demonstrating that infection by a microsporidian pathogen causes populations of a globally significant invasive ant to collapse to local extinction, providing a mechanistic understanding of a pervasive phenomenon in biological invasions: the collapse of established populations from endogenous factors. We apply this knowledge and successfully eliminate two large, introduced populations of these ants. More broadly, microsporidian pathogens should be evaluated for control of other supercolonial invasive social insects. Diagnosing the cause of unanticipated population collapse in invasive organisms can lead to applied solutions.
The once-extensive tallgrass prairie community of North America has been reduced to small remnant... more The once-extensive tallgrass prairie community of North America has been reduced to small remnants, many of which are surrounded by intensive corn (Zea mays) agriculture. We investigated adult cornrootworm beetles (Chrysomelidae: Diabrotica spp.), important pests of corn, on sunflowers (Asteraceae: Helianthus spp.) in prairie remnants in southeast Minnesota. Large numbers of beetles invaded the prairie from surrounding corn fields in late summer. D. barberi and D. virgifera were captured on sticky traps in all locations in the prairie, but abundance was much greater near the edge adjacent to corn. We observed D, barberi (but not D. virgifera) feeding extensively on sunflower pollen and occasionally on other flower parts, such as petak. Sunflowers located nearer corn fields sustained morefloral damage than those farther from o m. To determine the effect of beetle &mage on seed set, we enclosed sunflower heads in bags with either zero, two, or four D. barberi adults. Seed set was reduced in heads enclosed with D. barberi Thus, this agriculturalpest may interfere with the successful reproduction of sunflowers and possibly otherprairie composites thatflower in late summer. Given the small size of mostprairie remnants and the abundance of thisflowerrfeeding beetle in landscapes dominated by corn agriculture, D. barberi may affect the sustainability ofprairie plantpopulations. Un Efecto de Borde Causado por Escarabajos Adultos sobre Girasoles en Remanentes de Pastizales de Praderas Resumen: La que fuera alguna vez una comunidad de pastizales altos de pradera de Norteam6rica ha sido reducida a remanentespequefios, muchos de 10s cuales estan rodeados de tierras de cultivo intensivo de maiz (Zea mays). Znvestigamos 10s adultos del escarabajo (Chrysomelidae: Diabrotica spp.), una plaga importante del maiz, en los girasoles (Asteraceae: Helianthus spp.) en remanentes de pradera del sureste de Minesota. Grandes cantidades de escarabajos provenientes de los cultivos de maiz adyacentes invadieron la pradera hacia finales del verano. D. barberi y D. virgifera fueron capturados en trampas pegajosas en todas las localidades de la pradera, pero la abundancia fue mucho mayor cerca del borde adyacente a los cultivos de maiz. Observamos que D, barberi (pero no D. virgifera) se alimentaron extensivamente delpolen de girasoles y ocasionalmente en otraspartes de lasflores, como son losp6talos. Los girasoles ubicados cerca de los campos de maizpresentaron u n mayor dafio floral que aquellos alejados del maiz. Para detemzinar el efecto del dafio de 10s escarabajos en las semillas, encerramos cabezas de girasol en bolsas que contenian cero, dos o cuatro D. barberi adultos. Los juegos de semillas fueron reducidos en las cabezas encerradas con D. barberi Por lo tanto, esta plaga agricola puede interferir con la reproduccion exitosa de los girasoles y posiblemente de otros elementos de las praderas que florean hacia el final del verano. Dado elpequefio tamafio de la mayoria de 10s remanentes de la pradera y a la abundancia de estos escarabajos que se alimentan de flores en paisajes dominados por el cultivo de maiz, D. barberi podria afectar la sostenibilidad de las poblaciones de plantas de la pradera.
Flooding impacts ground nesting ant colonies by destroying the infrastructure housing and organiz... more Flooding impacts ground nesting ant colonies by destroying the infrastructure housing and organizing societal function. Here, we report the convergent evolution in distantly related ant species of a behavioral trait that minimizes costs of flooding: the construction of earthen levees around nest entrances. In a South American floodplain ecosystem, we observed five ant species constructing prominent earthen berms encircling nest entrances shortly after large rainfall events. In four of these species, experimental flooding of nests demonstrated that earthen berms sufficed to prevent floodwaters from entering the below ground portions of the nest. Additional manipulations revealed that levee breaching caused, pronounced, and extended reductions in food collection for two distantly related species. Foraging was preempted by the allocation of workers to repair the internal structure of the nest. These findings represent convergent evolution of a functionally important nest construction behavior in response to comparable selective forces.
Since the first report on introductions to Texas of Pseudacteon decapitatingflies, a variety of p... more Since the first report on introductions to Texas of Pseudacteon decapitatingflies, a variety of participants have released flies in a range of sites. The expansions of Pseudacteon populations have been systematically and widely monitored. Before 2002, the widely released initial species P. tricuspis Borgmeier did not become established. Severe drought in 1996-2001 and host-sizedependent sex ratio were proposed constraints in establishing this species. In recentyears, however, these limitations have been lifted in some areas by favorable weather,irrigation of release sites, and/or by use of a smaller Pseudacteon species, P. curvatus Borgmeier, not reliant on larger fire ant workers to produce females. Beginning in 2002, the USDA-APHIS collaboration with USDA-ARS and Texas Cooperative Extension programs began to supplement release sites in Texas beyondthose initiated by the University of Texas, Austin phorid flyproject. In 2005, privatecitizens began to participate in the spread of Pseudacteon to new sites. By fall 2006, P. tricuspis, expanding from releases between 1999 and 2001, was found on more than 3 million hectares of Central and Coastal Texas, while P. curvatus, withits later start, is only now beginning to expand at some sites. Pseudacteon that established more easily in mesic and moderate climates has difficulty surviving unfavorableweather in South Texas. However, two sites where flies "failed" to becomeestablished were revealed to be false negatives after the record rains of summer2007. Starting in late 2006, the first releases of P. obtusus Borgmeier in NorthAmerica established, and three to five additional species are being released. Resumen. Desde el primer reporte del estado de las introducciones en Texas de la mosca decapitadota Pseudacteon ha habido avances significativos en las actividadesde liberaci6n por una gran variedad de participantes. Un monitoreo sistematicode la expansi6n de las poblaciones de Pseudacteon se encuentra en
Know Your Enemy Fire ants accidentally introduced to North America from their native range in Arg... more Know Your Enemy Fire ants accidentally introduced to North America from their native range in Argentina have been hugely invasive and difficult to eradicate and caused both environmental and economic damage. Recently, another accidentally introduced Argentine ant, the tawny crazy ant, appears to be displacing the fire ants. How? LeBrun et al. (p. 1014 , published online 13 February; see the Perspective by Kaspari and Weiser ) show that tawny crazy ants have a chemical and behavioral response to the toxic bite of fire ants that vastly reduces their mortality during confrontations and that allows the tawny crazy ants to outcompete their rivals.
The microsporidian pathogen Myrmecomorba nylanderiae Plowes et al. infects introduced tawny crazy... more The microsporidian pathogen Myrmecomorba nylanderiae Plowes et al. infects introduced tawny crazy ants (Nylanderia fulva (Mayr)), and constitutes one of the first natural enemies known to attack this invasive ant. We assess how infection is transmitted within colonies and how infection impacts N. fulva colony fragment growth under carbohydrate‐deficient and carbohydrate‐sufficient dietary conditions. Carbohydrate scarcity is a common source of stress for ant colonies. Infected workers efficiently pass infection to developing larvae but all other potential pathways for within colony transmission are rare or non‐viable. For unknown reasons, queens within infected colony fragments are generally uninfected, limiting the role of transovarial transmission in intracolony transmission. In the laboratory, infection by M. nylanderiae primarily impacts the growth of N. fulva colonies by reducing pupal production. Colony growth showed a substantially greater impact under carbohydrate‐deficient conditions implying that the effect of the pathogen may depend on seasonally variable carbohydrate availability. In the colony growth assay, worker mortality did not differ with infection status under either nutrient regime. However, in a longer, direct test of survivorship, infected worker survivorship was significantly lower. Recently, some established N. fulva populations with high prevalence of M. nylanderiae infection have declined precipitously, though it is unknown if M. nylanderiae is a causative agent in these declines. The combination of chronic impacts, presence in North America, and potential association with population declines makes M. nylanderiae a promising prospect for the biological control of N. fulva.
Combating invasive species requires a detailed, mechanistic understanding of the manner and speed... more Combating invasive species requires a detailed, mechanistic understanding of the manner and speed with which organisms expand their ranges. Biological control efforts provide an opportunity to study the process of species invasions and range expansions under known initial conditions. This study examines the rate, pattern and mechanisms of spread for two populations of the biological control agent Pseudacteon tricuspis, phorid-fly
Summary1. Habitat disturbance and species invasions interact in natural systems, making it diffic... more Summary1. Habitat disturbance and species invasions interact in natural systems, making it difficult to isolate the primary cause of ecosystem degradation. A general understanding requires case studies of how disturbance and invasion interact across a variety of ecosystem – invasive species combinations.2. Dramatic losses in ant diversity followed the invasion of central Texas by red imported fire ants (Solenopsis invicta). However, recent manipulative studies in Florida revealed no effect on ant diversity following the removal of S. invicta from a disturbed pasture habitat, but moderate loss of diversity associated with their introduction into undisturbed habitat and no invasion occurred without disturbance. Thus, the importance of S. invicta in driving diversity loss and its ability to invade undisturbed systems is unresolved.3. We examine the distribution and abundance of a large monogyne S. invicta population and its association with the co‐occurring ant assemblage at a site in south Texas close to the aridity tolerance limit of S. invicta.4. We document that moisture modulates S. invicta densities. Further, soil disturbing habitat manipulations greatly increase S. invicta population densities. However, S. invicta penetrates all habitats regardless of soil disturbance history. In contrast, controlled burns depress S. invicta densities.5. In habitats where S. invicta is prevalent, it completely replaces native fire ants. However, S. invicta impacts native ants as a whole less strongly. Intriguingly, native ants responded distinctly to S. invicta in different environments. In wet, undisturbed environments, high S. invicta abundance disrupts the spatial structure of the ant assemblage by increasing clumping and is associated with reduced species density, while in dry‐disturbed habitats, sites with high S. invicta abundance possess high numbers of native species. Analyses of co‐occurrence indicate that reduced species density in wet‐undisturbed sites arises from negative species interactions between native ants and S. invicta. However, these same data suggest that the high native species density of abundant S. invicta sites in dry‐disturbed environments does not result from facilitation.6. Monogyne S. invicta populations play different roles in different environments, driving ant diversity loss in some, but being largely symptomatic of habitat disturbance in others.
Species abundances in natural systems are usually close to some equilibrium, making mechanisms th... more Species abundances in natural systems are usually close to some equilibrium, making mechanisms that maintain or prevent species coexistence difficult to discern. Biological control projects provide an opportunity to observe systems transition between equilibriums as a result of the influence of the newly introduced species. In the southeastern United States and Texas, species of phorid fly parasitoids are being sequentially introduced as control agents for imported fire ants. The first two species introduced, Pseudacteon tricuspis and P. curvatus, partition the host niche based upon body size and co‐exist broadly in their native range in Argentina, indicating they would form a co‐existing and complementary suite of parasitoids in North America. This study examines the interaction between these parasitoids at multiple temporal and spatial scales. Surprisingly, data at all scales reveal that as P. curvatus establishes at a site it competitively displaces P. tricuspis. However, the speed of this reduction appears to differ between ecoregions, suggesting that the rate of displacement depends on environment. At the site where P. curvatus has been established the longest, this population interaction approaches complete displacement. Tests of potential mechanisms causing this displacement reveal that direct competition for host workers alters the operational sex ratio of the P. tricuspis population, but the strength of this effect is insufficient to explain the displacement. Experiments reveal the operation of a strong, indirect effect whereby locally common species preempt reproductive opportunities from rarer species by inducing host behavioral defenses. Finally, a re‐examination of published data from their native range reveals that a previously overlooked negative relationship between the densities of these two species also exists there, suggesting that the same processes as those reported here also operate in South America.
... Am. Nat. 107: 737-760. Colwell, RK 1979. The geographical ecology of hum-mingbird flower mite... more ... Am. Nat. 107: 737-760. Colwell, RK 1979. The geographical ecology of hum-mingbird flower mites in relation to their host plants and carriers. In: JG Rodriguez, (Ed.). Recent ad-vances in acarology, Volume II, pp. 461-468. Aca-demic Press, New York. Colwell, RK 1986a. ...
Abignano, Giuseppina Ablin, Jacob Abou-Raya, Suzan Abrahamyan, Lusine Abu-Shakra, M. Mahmoud Abud... more Abignano, Giuseppina Ablin, Jacob Abou-Raya, Suzan Abrahamyan, Lusine Abu-Shakra, M. Mahmoud Abud-Mendoza, Carlos Ackerman, Ilana Adams, Jo Aeberli, Daniel Agarwal, Parul Ahedi, Harbeer Aitken, Dawn Ajeganova, Sofia Akai, Masami Akamatsu, Yasushi Akikusa, Jonathan Al-Mayouf, Sulaiman Alarc on, Graciela Albano-Aluquin, Shirley Albert, Daniel Albrecht, Katinka Alburquerque-Send ın, Francisco Aletaha, Daniel Alevizos, Ilias Ali, Shabana Alizai, Hamza Allanore, Yannick Allen, Kelli Almeida, Gustavo Alnaqbi, Khalid Alten, Rieke Alway, Stephen Ambrose, Nicola Amin, Shreyasee Amorim, Anita Amris, Kirstine An, JaeJin Anand, Vibha Anderson, Joel Anderson, Ronald J. Andr es, Mariano Andrews, James Angst, Felix Annapureddy, Narender Antivalle, Marco Antony, Benny Apostolopoulos, Diane Appenzeller, Simone Arima, Kazuhiko Aringer, Martin Arkema, Elizabeth Arnold, John Asanuma, Yu Asay, Jessica Askanase, Anca Askling, Johan Aslam, Fawad Assassi, Shervin Avina-Zubieta, J. Antonio Avouac, Jerome Bachmeyer, Claude Backhouse, Michael Backman, Catherine Badlissi, Fadi Baer, Alan Baker, Joshua Baker, Kenneth Baker, Nancy Baldini, Chiara Bannuru, Raveendhara Baraliakos, Xenofon Barbhaiya, Medha Barbour, Kamil Barker, Karen Barland, Peter Barnabe, Cheryl Barnado, April Baron, Murray Bartels, Christie Bartley, Emily Barton-Ellis, Carol Barton, Jennifer Basu, Neil Bathon, Joan Bearne, Lindsay Beasley, Marcus Beaton, Cleopatra Becker, Mara Bejarano, Victoria Benseler, Susanne Berard, Roberta Bergman, Martin Bergsten, Ulrika Bergstra, Sytske Anne Bermas, Bonnie Bernatsky, Sasha Berner, Jon Bertoli, Ana Beukelman, Timothy Bhutani, Gita Bieler, Theresa Bili, Androniki Bindawas, Saad Birmingham, Trevor Bjornsson, Johannes Blalock, Susan Bolen, Julie Bolster, Marcy Boneparth, Alexis Boonen, Annelies Booth, Sarah Borba, Eduardo Borenstein, David Bove, Allyn Bowen, Catherine Bowman, Simon J. Boyer, Katherine Bradley, Laurence Brady, Teresa Brasington, Richard Braun, Juergen Bremander, Ann Brennan-Olsen, Sharon Brenton-Rule, Angela Bridges, Alan Brito-Zeron, Pilar
The data file has 6 spreadsheets. Acido. Groom. - Sinvicta venom: For methods see - Acidopore gro... more The data file has 6 spreadsheets. Acido. Groom. - Sinvicta venom: For methods see - Acidopore grooming response - S. invicta venom. Acido. Groom. - other sp venom: For methods see - Acidopore grooming response - other venoms Detox. Capacity CO2 Anesthetiz.: For methods see - Detoxification capacity assay – S. invicta venom Detox Capacity Acidopor. Sealed: For methods see - Detoxification capacity assay – S. invicta venom Acid. Groom. S.A. Vid. Crufipes: For methods see - Video Analysis - South American Interactions Acid. Groom. S.A. Vid. Nfulva: For methods see - Video Analysis - South American Interaction
Biological invasions represent communities in flux. Although stasis is never the rule in nature, ... more Biological invasions represent communities in flux. Although stasis is never the rule in nature, biological interactions in communities usually occur within a framework of shared ecological and evolutionary history. Consequently, biological invasions represent unique opportunities to study dynamics that can otherwise be difficult to observe (Elton 1958). Invasive ants are excellent organisms with which to pursue this goal, in part because ants as a group play a variety of important ecological roles within biological communities (Hölldobler and Wilson 1990). Ant invasions hold much potential for improving an understanding of ecological processes in general, as well as of interactions more specific to myrmecology. For instance, the dynamics that exist during ant invasions may reveal the traits that promote behavioural or ecological dominance. Furthermore, highly successful invasive ant species are often less conspicuous in their native ranges, so identification of the factors responsi...
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Papers by Edward LeBrun