Recent Invasive Species Research Articles

Long‐term analysis of body condition reveals species coupling and the impacts of an invasion

AbstractPredator–prey coupling can result in oscillations of predator–prey densities. These oscillations in predator–prey densities correspond to oscillations in intraspecific competition where a high population density causes high intraspecific competition. Strong coupling of native species can however be disrupted by the introduction of invasive species into food webs. Here, we investigated how the body condition (body mass relative to body length) of a predator, lake trout, and its primary prey, cisco, changed as their respective population densities shifted. We found that the body condition of lake trout and cisco was strongly influenced by their respective population densities, that is, density dependence. The body conditions of lake trout and cisco were also inversely related, which highlights strong predator–prey coupling. Further, we were able to detect the impacts of a recent invasive species, Bythotrephes, as we saw size‐specific shifts in the body condition of prey following the invasion. Overall, this study highlights how the long‐term study of a simple measure, body condition, can reveal predator–prey coupling and yield new insights into the impacts of an invasive species.

Aphelinus nigritus Howard (Hymenoptera: Aphelinidae) Preference for Sorghum Aphid, Melanaphis sorghi (Theobald, 1904) (Hemiptera: Aphididae), Honeydew Is Stronger in Johnson Grass, Sorghum halepense, Than in Grain Sorghum, Sorghum bicolor.

How aphid parasitoids of recent invasive species interact with their hosts can affect the feasibility of biological control. In this study, we focus on a recent invasive pest of US grain sorghum, Sorghum bicolor, the sorghum aphid (SA), Melanaphis sorghi. Understanding this pest's ecology in the grain sorghum agroecosystem is critical to develop effective control strategies. As parasitoids often use aphid honeydew as a sugar resource, and honeydew is known to mediate parasitoid-aphid interactions, we investigated the ability of SA honeydew to retain the parasitoid Aphelinus nigritus. Since SAs in the US have multiple plant hosts, and host-plant diet can modulate parasitoid retention (a major component in host foraging), we measured SA honeydew sugar, organic acid, and amino acid profiles, then assessed via retention time A. nigritus preference for honeydew produced on grain sorghum or Johnson grass, Sorghum halepense. Compared to a water control, A. nigritus spent more time on SA honeydew produced on either host plant. Despite similar honeydew profiles from both plant species, A. nigritus preferred honeydew produced on Johnson grass. Our results suggest the potential for SA honeydew to facilitate augmentation strategies aimed at maintaining A. nigritus on Johnson grass to suppress SAs before grain sorghum is planted.

Geographical distribution and phylogenic relationships of Hirschmanniella diversa Sher (Nematoda: Pratylenchidae) in Japan

Summary Hirschmanniella diversa and H. imamuri parasitise the lotus, Nelumbo nucifera. Hirschmanniella spp. are the most important pests of lotus cultivation in Japan, but the distribution and species dominancy are not fully understood. In this study, we aimed to collect Hirschmanniella spp. individuals from lotus roots in the major lotus cultivation areas in Japan and identify them morphologically and molecularly using the 18S, D2-D3 regions of rRNA and mitochondrial cytochrome c oxidase subunit I (mtCOI). Hirschmanniella oryzae, commonly known to cause damage on rice in Japan, was also obtained and analysed for inter- and intraspecies sequence variations. All individuals of the genus Hirschmanniella extracted from lotus roots in 16 fields in ten prefectures were identified as H. diversa morphologically and molecularly. This result revealed that H. diversa is a dominant Hirschmanniella species parasitising lotus in Japan. Meanwhile, intraspecific sequence variations in H. diversa were relatively higher in the mtCOI (1-21 bases, ≦5.3%) than in the 18S rRNA and D2-D3 of 28S rRNA (0.0-0.3% and 0.0-0.4%, respectively) and in those of H. oryzae. Based on the mtCOI sequences, five haplotypes were identified and each haplotype was distributed in relatively close regions or regions in which the same lotus cultivars were grown, although further studies are required to verify this assertion. The morphological and genetic variations were higher in H. diversa than in H. oryzae (no intraspecific sequence variation in mtCOI), suggesting that H. diversa was not a recent invasive species.

Development of a Taqman Real-Time PCR for the Identification of Haemaphysalis longicornis (Acari: Ixodidae).

Haemaphysalis longicornis Neumann, a vector of various pathogens with medical and veterinary importance, is a recent invasive species in the United States. Like many tick species, discerning H. longicornis from congeners can be a challenge. To overcome the difficulty of morphological identification, a Taqman quantitative real-time PCR based on the internal transcribed spacer gene (ITS2) was developed for quick and accurate identification of H. longicornis with a detection limit of as low as 19.8 copies. We also applied the assay to 76,004 archived ticks and found 37 ticks were H. longicornis. One H. longicornis was submitted from Warren, Somerset County, New Jersey in June 2015, 2 yr earlier than the initial report from the United States. None of these 37 H. longicornis was positive for Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, B. miyamotoi, B. mayonii, Babesia microti, or Ehrlichia muris–like agent.

On the potential of documenting decadal-scale avifaunal change from before-and-after comparisons of museum and observational data across North America

Studies of biodiversity dynamics have been cast on either long (systematics) or short (ecology) time scales, leaving a gap in coverage for moderate time scales of decades to centuries. Large-scale biodiversity information resources now available offer opportunities to fill this gap for many parts of the world via detailed, quantitative comparisons of assemblage composition, particularly for regions without rich time series datasets. We explore the possibility that such changes in avifaunas across the United States and Canada before and after the first three decades of marked global change (i.e., prior to 1980 versus after 2010) can be reconstructed and characterized from existing primary biodiversity data. As an illustration of the potential of this methodology for sites even in regions not as well sampled as the United States and Canada, we also explored changes at a single site in Mexico (Chichén-Itzá). We analyzed two large-scale datasets: one summarizing bird records in the United States and Canada before 1980, and one for the same region after 2010. We used probabilistic inventory completeness analyses to identify sites that have avifaunas that have likely been inventoried more or less completely. We prepared detailed comparisons between the two time periods to analyze species showing distributional changes over the time period analyzed. We identified 139 sites on a 0.05° grid that were demonstrably well-inventoried before 1980 in the United States and Canada, of which 108 were also well-inventoried after 2010. Comparing presence/absence patterns between the two time periods for 601 bird species, we found significant spatial autocorrelation in overall avifaunal turnover (species gained and lost), but not in numbers of species lost. We noted potential northward retractions of ranges of several species with high-latitude (boreal) distributions, while other species showed dominant patterns of population loss, either rangewide (e.g., Tympanuchus cupido) or regionally (e.g., Thryomanes bewickii). We developed linear models to explore a suite of potential drivers of species loss at relatively fine-grained resolutions (<6 ​km), finding significant effects of precipitation increase, particularly on the eastern border of the United States and Canada. Our exploration of biotic change in Chichén-Itzá included 265 species and showed intriguing losses from the local avifauna (e.g., Patagioenas speciosa), as well as vagrant and recent invasive species in the Yucatán Peninsula. The present work documents both the potential for and the problems involved in an approach integrating primary biodiversity data across time periods. This method potentially allows researchers to assess intermediate-time-scale biodiversity dynamics that can reveal patterns of change in biodiversity-rich regions that lack extensive time-series information.

The habitat preferences of Meta bourneti (Simon, 1922) (Araneae: Tetragnathidae) in the UK differ from populations in southern Europe

Invasive species often expand their niche and broaden their habitat preferences when they colonize new areas. The cave orb spider Meta bourneti (Simon, 1922) is thought to be a relatively recent invasive species in the UK, and anecdotal evidence suggests that it might be found in a broader range of habitats in the UK than in its native range in southern Europe. In the present study, I investigate these claims, by first comparing the distribution and habitat preferences of M. bourneti to the more common cave orb spider Meta menardi (Latreille, 1804) in the UK using historic data from the UK Spider Recording Scheme. Second, I use data obtained mainly from published studies to compare M. bourneti populations in the UK with those from France, Italy, and Spain. The results confirm that the M. bourneti habitat preferences are significantly different from both M. menardi and from populations in southern Europe in that the UK populations are predominantly found in non-cave dark habitats such as under manhole covers, in culverts, and icehouses with only 11% of records coming from caves and mines. My results indicate that M. bourneti offers significant potential for further studies including citizen science projects since several observations were made in private gardens.

Phenology, Development, and Parasitism of Allium Leafminer (Diptera: Agromyzidae), a Recent Invasive Species in the United States.

Allium leafminer, Phytomyza gymnostoma (Diptera: Agromyzidae), is an invasive species first recorded in the Western Hemisphere in 2015 and has expanded its range into northeastern and MidAtlantic states. Its host range encompasses Allium species grown for food and ornamentals, weedy species, species used for pollinator provisioning, and species of conservation concern. Using field and laboratory studies, we advanced methods for rearing, developed a phenology model for spring emergence, describe pupal development, and report on parasitism. Spring emergence was best detected by scouting wild alliums as opposed to emergence cages, and modeled using 350 degree-days above a lower threshold of 1.0°C. Spring adult flight occurred for about 5 wk. Larval development required 22 and 20 d at 17.5 and 25°C, respectively. Pupal development progressed along a color gradient, and an initial presence of fat cell clusters and an air bubble, followed by an exarate pupa. Pupal developed at 3-5% per day at 3°C and reached 25% per day at 21.5°C, but development was not successful at 30°C. Although parasitism rates were low, we documented two Chalcidoidea parasitoids, Halticoptera circulus (Walker) (Hymenoptera: Pteromalidae) and Chrysocharis oscinidis Ashmead (Hymenoptera: Pteromalidae). Together, these data provide baseline information to advance IPM for this invasive species both in crops and noncrop areas.

Border interceptions of forest insects established in Australia: intercepted invaders travel early and often

Invasive forest insects continue to accumulate in Australia (and worldwide) and cause significant impacts through costs of prevention, eradication and management, and through productivity losses and environmental and biodiversity decline. We used our recent non-native Australian forest insect species inventory to analyse border interception rates (2003–2016) of established species, and link interception frequencies with biological traits, historical establishment patterns, commodities and countries of origin. The strongest predictor of interception frequency was year of establishment. Polyphagous species were more likely to be intercepted, as were more concealed species, although this latter likely reflects the higher interceptions of bostrichid borers and other wood-boring Coleoptera relative to other taxa. Interceptions occurred more often for species native to Asia; in contrast, interceptions from other regions were more likely to be of species invasive there. While interception frequencies did not provide a good overall indicator of contemporaneous species establishments, wood and bark borers were more closely linked for establishments and interceptions. The first fifty forest insect species to establish comprised 85% of all border interceptions of established species between 2003 and 2016, while the most-recent fifty species represented just 6% of interceptions. We suggest that early-establishing species are among the “super-invaders” that continue to move globally, while more recent invasive species may be exploiting new trade pathways, new commodity associations, or changes in dynamics in their countries of origin.

Phenology of Drosophila species across a temperate growing season and implications for behavior.

Drosophila community composition is complex in temperate regions with different abundance of flies and species across the growing season. Monitoring Drosophila populations provides insights into the phenology of both native and invasive species. Over a single growing season, we collected Drosophila at regular intervals and determined the number of individuals of the nine species we found in Kansas, USA. Species varied in their presence and abundance through the growing season with peak diversity occurring after the highest seasonal temperatures. We developed models for the abundance of the most common species, Drosophila melanogaster, D. simulans, D. algonquin, and the recent invasive species, D. suzukii. These models revealed that temperature played the largest role in abundance of each species across the season. For the two most commonly studied species, D. melanogaster and D. simulans, the best models indicate shifted thermal optima compared to laboratory studies, implying that fluctuating temperature may play a greater role in the physiology and ecology of these insects than indicated by laboratory studies, and should be considered in global climate change studies.

High genetic diversity in a 'recent outbreak' spider mite, Tetranychus pueraricola, in mainland China.

Tetranychus pueraricola is a newly reported spider mite that occurs frequently in mainland China. It is possible that this species was introduced from elsewhere and became a serious pest recently. However, the correct identification of red-pigmented spider mites has repeatedly proven problematic. There is also the possibility that T. pueraricola in China was long misidentified as its sibling species, Tetranychus urticae (red form). To test which of these two scenarios is the more likely, individuals from 14 populations of T. pueraricola and five populations of T. urticae (red form) in China were sampled and genotyped using mitochondrial COI and microsatellite loci. Unlike a recent invasive species, the genetic diversity of T. pueraricola was very high with high mitochondrial genetic diversity (16 haplotypes), high effective alleles (Ne = 2.038 ± 0.081) and expected heterozygosity (He = 0.395 ± 0.016). Surprisingly, we found that all T. urticae (red form) populations shared only one mitochondrial haplotype and showed quite low genetic diversity (Ne = 1.443 ± 0.055; He = 0.234 ± 0.025) which was even lower than that of the green form of T. urticae in mainland China from a previous study. We did not detect significant signals of recent bottlenecks for most populations from both species. These results suggest T. pueraricola is unlikely to be a recent invasive pest but a species that has existed in China for a long time. It is probable that T. pueraricola in China has long been misidentified as T. urticae (red form).

Spreading of Vespa velutina in northwestern Spain: influence of elevation and meteorological factors and effect of bait trapping on target and non-target living organisms

The yellow-legged hornet, Vespa velutina, is a recent invasive species in Galicia (NW Spain). Its invasion has an important socio-economic impact because it preys upon honeybees (Apis mellifera) and other crucial insect pollinators. The dispersal of this species must be monitored to minimise the damage it causes and to take the necessary control actions. The aims of this study were to determine target and nontarget living organisms captured by bait trapping and to compare the distribution patterns of V. velutina and the autochthonous V. crabro. Altitude and weather conditions played important roles in hornet behaviour. The traps placed in low-altitude coastal areas contained the most yellow-legged hornets. In contrast, the autochthonous hornet occurred in relatively greater numbers in the traps hung in high-altitude areas. High minimum temperatures, dew temperature, relative humidity and low maximum temperatures favour the occurrence and spread of V. velutina. These conditions are common in the coastal areas of this territory and promoted the rapid dispersal of this pest. The traps used were not bait-selective, so many other arthropod organisms were captured along with the hornet. Therefore, the use of species-selective baits is required for the ecofriendly effective management of this insect pest.

A Statewide Survey for Container-Breeding Mosquitoes in Mississippi.

Container-breeding mosquitoes are important in public health due to outbreaks of Zika, chikungunya, and dengue viruses. This paper documents the distribution of container-breeding mosquito species in Mississippi, with special emphasis on the genus Aedes. Five sites in each of the 82 Mississippi counties were sampled monthly between May 1 and August 31, 2016, and 50,109 mosquitoes in 14 species were collected. The most prevalent and widely distributed species found was Ae. albopictus, being found in all 82 counties, especially during July. A recent invasive, Ae. japonicus, seems to be spreading rapidly in Mississippi since first being discovered in the state in 2011. The most abundant Culex species collected were Cx. quinquefasciatus (found statewide), Cx. salinarius (almost exclusively in the southern portion of the state), and Cx. restuans (mostly central and southern Mississippi). Another relatively recent invasive species, Cx. coronator, was found in 20 counties, predominantly in the southern one-third of the state during late summer. Co-occurrence data of mosquito species found in the artificial containers were also documented and analyzed. Lastly, even though we sampled extensively in 410 sites across Mississippi, no larval Ae. aegypti were found. These data represent the first modern statewide survey of container species in Mississippi, and as such, allows for better public health readiness for emerging diseases and design of more effective vector control programs.

Evaluation of tetrodotoxins in puffer fish caught along the Mediterranean coast of Spain. Toxin profile of Lagocephalus sceleratus

Although consumption of Tetraodontidae species is prohibited in the EU, intoxications are still reported. The evaluation of tetrodotoxins (TTXs) by mass spectrometry (LC-MS/MS and LC-HRMS) and a screening immunoassay (mELISA) in tetraodontid fishes caught along the Western Mediterranean Sea revealed high concentrations of TTXs in Lagocephalus sceleratus while no TTXs were identified in L. lagocephalus and Sphoeroides pachygaster individuals. The high TTXs content found in the L. sceleratus analysed herein demonstrate the occurrence of highly toxic puffer fish in the Western Mediterranean Sea. Being L. sceleratus a recent invasive species in the Mediterranean, surveillance, risk assessment and risk management measures are necessary. The strategy used within this research work could be a valuable tool for future food safety monitoring.

Informe de seis especies de pentatomidos nuevas en Puerto Rico

Presentamos los primeros informes para seis especies de pentatomidos en Puerto Rico. Entre ellas se hallan dos especies depredadoras: Apateticus lineolatus (Herrich Scháffer) y Tylospilus acutissimus (Stál) pertenecientes a la subfamilia Asopinae. Informamos también cuatro especies fitófagas, tres pertenecientes a la subfamilia Pentatominae: Berecynthus hastator (R), Chlorocoris tau Spinola, y Acrosternum (Chinavia) ubicum Rolston y un miembro de la subfamilia Discocephalinae, Alitocoris brunneus Sailer. La especie B. hastator ha sido identificada en la literatura como un vector de enfermedades en palmas y A. brunneus aparenta ser una nueva especie invasora. Estos nuevos informes elevan el número de especies de Pentatomidae informadas de 42 a 48, y el número de géneros de 29 a 34.

Three Members of the Bemisia tabaci (Hemiptera: Aleyrodidae) Cryptic Species Complex Occur Sympatrically in Argentine Horticultural Crops.

The whitefly, Bemisia tabaci (Gennadius), is a cryptic species complex that attacks >600 different species of plants and transmits several plant viruses causing severe economic losses. Until 2010, the B. tabaci complex comprised 24 distinct putative species. Recently, at least 15 new species have been reported. The objective of this study was to identify B. tabaci species present in bean, melon, and tomato crops in Argentina by applying phylogenetic analyses and pairwise comparison of genetic distances of mitochondrial cytochrome c oxidase subunit I (mtCOI) sequences. The 39 proposed whitefly species were identified with both analyses, and the presence in Argentina of one indigenous species, New World 2 (NW2), and two introduced species, Middle East-Asia Minor one (MEAM1) and Mediterranean, was confirmed. Common bean crop presented the three whitefly species detected, with NW2, MEAM1, and Mediterranean being present all together under field conditions. Also, Mediterranean was the only species identified in tomato, whereas MEAM1 was found in melon. To the best of our knowledge, Mediterranean is a recent invasive species in open-field agriculture in the American continent and in greenhouse tomato in Argentina. Additionally, we provide the first report of MEAM1 in common bean and melon. These findings raise several questions on the future scenario of B. tabaci and the viruses it transmits in Argentina.

Earthworm Invaders Have Huge Implications for Forest Health

Earthworm Invaders Have Huge Implications for Forest Health

An ethnobotany of Western Cape Rasta bush medicine

Aims of this studyThis descriptive ethnobiological research is the first documentation of the materials utilized in the pharmacopeia of a novel group of herbalists, Rasta bush doctors, found in the botanically diverse Western Cape of South Africa. This article suggests that medicinal plants used by bush doctors unite the disparate ethnomedicines found in South Africa. Materials and methodsEthnospecies name and parts used were recorded during detailed inventories of 39 bush doctors. Collection of voucher specimens for botanical identification occurred in 15 locations. Herbal remedies were classified into use categories and were compared to historical ethnobotanical literature to ascertain previous cultural affiliations. ResultsThere were 205 ethnospecies found in the Rastafari ethnobiology, 181 were used medicinally. Ethnospecies belong to 71 plant families and 71% belonged to six plant families: Rutaceae (13), Asteraceae (13), Apiaceae (9), Lamiaceae (8), Fabaceae (8), and Euphorbiaceae (7). The majority of remedies (49%) were foliage. Medicinal plants treated over 30 ailments including: gastrointestinal symptoms (11%), urogential complaints (11%), skin ailments (9%), and cardiovascular diseases (8%). Bush doctors appropriated remedies traditionally important to Zulu, KhoiSan, European and Xhosa healing traditions. Novel plants and plant utilization were noted for 22 plant species. ConclusionsUse of previously undocumented plant materials as medicinals denote distinct local knowledge including novel Rastafarian utilization of herbs for spiritual and ritual purposes. The range of the largely herbaceous pharmacopeia is narrow compared to the region's highly biodiverse materials and historical records of medicinal use. Bush doctors’ experimentation with known herbal remedies illustrates a striking level of cross-cultural adaptation. This syncretic pharmacopeia reflects the cultural diversity of Southern Africa, drawing upon recent invasive species, European influence and traditional herbs used by the KhoiSan, Zulu and Xhosa peoples.

Age-specific light preferences and vertical migration patterns of a Great Lakes invasive invertebrate, Hemimysis anomala

We use a combination of spectral sensitivity analyses, laboratory behavioral observations and field distributions of a vertically migrating invertebrate, Hemimysis anomala (a recent invasive species to the Laurentian Great Lakes of North America), to determine if light preference and timing of emergence has an ontogenetic component. Juvenile Hemimysis (<4.5mm) preferred light levels between 10−3.4and 10−2.4mylux— a Hemimysis-specific unit of brightness derived from visual pigment analyses (wavelength of maximum absorbance=500nm; 1mylux~159lx). These preferred light levels are equivalent to those present during nautical twilight on the Earth's surface and were several orders of magnitude brighter than those most preferred by adults (>4.5mm) in the laboratory (10−6.4 to 10−7.4mylux). Both size classes completely avoided light levels of 10−0.4mylux and greater, which are representative of daytime light levels at the Earth's surface. Net hauls taken at ~20-min intervals from sunset to the end of nautical twilight on two sampling occasions on Seneca Lake, New York (sampling depth = 2m) revealed that juveniles emerged into the water column during civil twilight. Adult Hemimysis emerged later during nautical twilight when juveniles had already reached their maximum abundance in the water column. Laboratory-derived light preferences successfully predicted the timing of emergence and time of maximal abundance of both size classes on both sampling occasions. This study is one of the first to demonstrate that Hemimysis diel vertical migration has an ontogenetic component and to report the specific light levels likely to initiate and limit vertical movements.

Carbon-based balanced trophic structure and flows in the offshore Lake Ontario food web before (1987–1991) and after (2001–2005) invasion-induced ecosystem change

Replicate mass-balanced solutions to Ecopath models describing carbon-based trophic structures and flows were developed for the Lake Ontario offshore food web before and after invasion-induced disruption. The food webs link two pathways of energy and matter flow: the grazing chain (phytoplankton–zooplankton-fish) and the microbial loop (bacteria–protozoans) and include 19 species-groups and three detrital groups. Mass-balance was achieved by using constrained optimization techniques to randomly vary initial estimates of biomass and diet composition. After the invasion, production declined for all trophic levels and species-groups except Chinook salmon. The trophic level (TL) increased for smelt, adult sculpin, adult alewife and Chinook salmon. Changes to ecotrophic efficiencies indicate a reduction in phytoplankton grazing, increased predation pressure on Mysis, adult smelt and alewife and decreased predation pressure on protozoans. Specific resource to consumer TTE changed; increasing for protozoans (8.0–11.5%), Mysis (0.6–1.0%), and Chinook salmon (1.0–2.3%) and other salmonines (0.4–0.5%) and decreasing for zooplankton (20.2–15.1%), prey-fish (9.7–8.8%), and benthos (1.7–0.6%). Direct trophic influences of recent invasive species were low. The synchrony of the decline in PP and species-group production indicates strong bottom-up influence. Mass balance required an increase of two to threefold in lower trophic level biomass and production, confirming a previously observed paradoxical deficit in lower trophic level production. Analysis of food web changes suggest hypotheses that may apply to other similar large pelagic systems including, (1) as pelagic primary productivity declines, overgrazing of zooplankton results in an increase in protozoan production and a loss of trophic transfer efficiency, (2) habitat and food web changes increased Mysis predation on Diporeia and contributed to their recent decline, and (3) production of Chinook salmon, the primary piscivore, was uncoupled from pelagic production processes. This study demonstrates the value of food web models to better understand the impact of invasive species and to develop novel hypotheses concerning trophic influences.

Palynological assessment of Holocene mangrove vegetation at the American Memorial Park, Saipan, Northern Mariana Islands

Pollen and spores recovered from three cores of Holocene to recent deposits from the island of Saipan indicate the presence of mangrove vegetation, including Bruguiera and Acrostichum, on the island previous to World War II. The occurrence of Casuarina equisetifolia Linneaus 1759, from cores elsewhere on the island of Saipan, at depths predating the arrival of humans to the island, suggest that this tree species is endemic to Saipan rather than a recent invasive species. These findings will assist in replanting native vegetation once destroyed through wartime activities on the island.