Rapid Assessment of Invasive Alien Species in Wetlands of Lao PDR

Niche and range shifts of invasive species are essential in assessing the risk of biological invasions and developing ecological niches and species distribution theories. Studies on invasive aquatic species' niche and range shifts have important implications for conserving aquatic invasive ecosystems. Here we used niche and range dynamic models to explore niche and range shifts of the golden apple snail Pomacea canaliculata, one of the world's most invasive aquatic species. The major factors responsible for P. canaliculata niche shifts in native and invaded regions were minimum temperature of the coldest month and precipitation in the warmest quarter. The niche and range of invasive P. canaliculata snails were not conserved relative to their native counterparts and had a broader niche and larger range, which are consistent with the findings that invasive P. canaliculata snails could survive in colder, hotter, drier, and wetter climates. Given that niche nonconservatism could result in range nonconservatism and small increases in niche breadth could induce large range expansions, niche shifts might provide a more sensitive indicator of invasion risk than range shifts. In contrast to most invasive species that show conservatism of their native niches, we observed high niche lability between the P. canaliculata snails in the native and invaded regions. Our findings indicate that the golden apple snail is a high‐risk invasive aquatic species for its ability to aggressively proliferate through its rapid reproduction rate, fast growth as suggested by previous studies, and also for its highly labile niches and ranges, which facilitates adaptation to the climate of the introduced regions.

Environmental risk assessment for invasive alien species: A case study of apple snails affecting ecosystem services in Europe

The golden apple snail (Pomacea canaliculata), a highly invasive species, poses a substantial threat to rice crops and causes significant economic losses in wetland rice cultivation, threatening biodiversity and impacting human health. Pomacea canaliculata attacks cause significant losses, accounting for approximately 80% of rice production. The use of chemical molluscicides became a common practice among the farmers to control the golden apple snail’s outbreak, despite its harm to the environment and health. Biopesticide was an alternative way of controlling the golden apple snail with minimal effect on the environment and human health. In addition, essential oils as biopesticides have a high potency as an eco-friendly pesticide for controlling invasive apple snails, which can be used to replace chemical pesticides. This study was aimed to evaluate the effectiveness and the toxicity of turmeric essential oil and wood vinegar against golden apple snail. The bioassay test on golden apple snails was tested on varied concentrations (200, 400, and 600 ppm) of turmeric essential oil and wood vinegar, with three replications for each treatment. Mortality rates were recorded at 24, 48, 72, 96, and 120 hours after treatment. The highest mortality rate of golden apple snails for turmeric essential oil (600 ppm) is 83.3% and wood vinegar (600 ppm) is 76.6% recorded at 120 hours after treatment. Based on the one-way ANOVA analysis of turmeric essential oil and wood vinegar application, it was resulted significant difference in mean mortality of golden apple snails (F (7, 92) = 3.650, p = 0.002). Tukey’s HSD Test for multiple comparisons found that the mean value of golden apple snail mortality was significantly different between turmeric (600 ppm) and wood vinegar (200 ppm) (p = 0.012, 95% C.I. = 0.4172, 5.8494). Both biopesticides showed a mode of action leading to mortality but turmeric essential oil is strongly recommended for biopesticide applications to prevent golden apple snail infestations. Thus, the essential oil of turmeric has a good potential as an effective molluscicide compared to wood vinegar for controlling golden apple snails.

This study aims to enhance the discussion about the usefulness of invasive animals for biodiversity assessment in Mekong Delta provinces. Data were used for the area of 5.331 km2 in Ca Mau Province [1]. The data covered the period 2017 – 2018. To implement this evaluation, the analyses were based on the scientific documents “Introduction to Invasive Species in Vietnam” of Vietnam Agency of Biodiversity Conservation and “The Aquatic Invasive Species Assessment and Management Plan” Massachusetts Department of Conservation and Recreation, and the working experiences of research group for the invasive species assessment [2, 3]. The results found two invasive animal species such as apple snail – Pomacea canaliculata (Lamarck, 1819) and Amazon sailfin catfish – Pterygoplichthys pardalis (Castelnau, 1855) [2]. These species mapped in the map of Ca Mau Province. The problem of invasive species has become an important issue of concern for the local government and community. However, if appropriate targets for ecosystem management planning is suggested, these “invaders” can be prevented the spread of invasive species.

The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species were differently affected by grazing. Duckweed had almost disappeared after 6 and water hyacinth after 21 days, whereas morning glory remained at 80% of initial biomass after 32 days. Snail growth was lowest on morning glory and, when all plant species were simultaneously presented to snails, this plant was not preferred. We suggest that the negative effect the golden apple snail had on the growth of these plant species in field enclosures is present in the natural environment as well. This new and intense herbivory could have serious negative effects on invaded freshwater ecosystems in this region.

Biodiversity loss caused by invasive species may soon surpass the damage done by habitat destruction and fragmentation. Biological invasions are an important component of human-caused global environmental change. Invasive alien species are now a major focus of global conservation concern. The decisions need to be made on whether benefits derived from the invasive spread of an alien species outweigh the reduced value of ecosystem services, e.g. the loss of grazing land in areas invaded with Lantana camara and Senna occidentalis . It is necessary to consider actions to deal with the current problems caused by invasive species and to reduce the magnitude of the problem in the future. The present catalogue on invasive alien plant species of the northwestern & Western Ethiopia is therefore timely one. It focuses on some species of invasive alien plants in Ethiopia. These include the most serious invasives, such as Alternanthera philoxeroides, Cassia uniflora, Chromolaena odorata, Eichhornia crassipes, Lantana camara, Parthenium hysterophorus , Senna obtusifolia and others. I am confident that this publication will be immense value to foresters, environmentalists, field researchers and conservation managers to pay attention on the ecological impact of invasive aliens both at the species and at the ecosystem levels. Keywords : Biodiversity, invasive species, conservation, environmental change DOI : 10.7176/ALST/74-04 Publication date :May 31 st 2019

Laboratory feeding observations confirm that the golden apple snail (Pomacea canaliculata Lamarck, 1822) is a voracious predator of phylactolaemate bryozoans. An invasive species in Southeast Asia since the early 1980s, the snail now occupies most freshwater ponds, lakes, and rivers throughout the region. Despite the absence of baseline data, it appears that the snail has had a profound effect on the freshwater bryozoan community, including both tubular and globular colonies. The common gymnolaemate, Hislopia, is less affected. From repeated feeding trials it appears that indigenous apple snails (Pila spp.) do not graze on bryozoans; nor does the large indigenous Cipangopaludina chinensis.

Golden Apple Snail (Pomacea canaliculata) secretion has traditionally been used for wound healing due to its high protein content, which promotes cell regeneration and inhibits inflammation. This study aims to utilize this secretion to formulate a topical gel for burn treatment, providing a controlled use for the abundant, invasive species in agricultural areas. Gel formulations with varying secretion concentrations (10%, 15%, and 20%) were evaluated for organoleptic properties, homogeneity, pH, adhesion, spreadability, and viscosity. Results indicated that all formulations were homogeneous and had pH values within the acceptable range (4.5-6.5). The 15% secretion gel showed the highest user acceptance and optimal balance between spreadability and adhesion, but all formulations had higher than standard viscosity and lower spreadability. Adjusting carbopol concentration is recommended to improve the gel's physical properties. The 15% formulation is the most promising for effective topical application.

Invasive alien species (IAS) influence the trophic organisation and food web structure in an invaded ecosystem, and therefore, it is imperative to quantify the resultant ecological impacts. The globally recognised ecosystem modelling platform, Ecopath with Ecosim, was used to delineate the impacts of IAS on a tropical freshwater pond ecosystem in India. We analysed the trophic interactions, consumption patterns, prey overlap and mixed trophic impacts of three co-existing invasive alien fish species, African catfish (Clarias gariepinus), suckermouth catfish (Pterygoplichthys pardalis) and Mozambique tilapia (Oreochromis mossambicus), on other functional groups in the ecosystem. Together, the three IAS shared 11% of the total energy consumption and about 50% of the energy consumption by the fish species/groups. There was no predation mortality for African catfish and suckermouth catfish, and a very low estimate for the same was recorded for tilapia (0.64year-1). The IAS shared high mean prey overlap with the native fish groups (Garra sp., Etroplus suratensis, Systomus sarana, Chanda nama and various small species of the cypriniform genera Puntius, Rasbora and Devario) indicating a substantial competition between alien and native species in the ecosystem. Consequently, the three IAS exhibited higher mean negative mixed trophic impacts on these functional groups. A very high Finn's cycling index (39.59%), a low relative ascendency (28.5%) and a very low system robustness (0.07) were observed compared to similar ecosystems, and the baseline values. These indices exposed the vulnerability of the ecosystem towards perturbations, which could be due to the presence of multiple alien invasive species. Mitigating the impacts of IAS should involve a combination of approaches, including eradication through draining and harvesting, high-density stocking of similar trophic level fish in the pond, and local and national level policy interventions.

The impact of invasive plant species in national parks and forests in Vietnam is undocumented and management plans have yet to be developed. Ten national parks, ranging from uncut to degraded forests located throughout Vietnam, were surveyed for invasive plant species. Transects were set up along roads, trails where local people access park areas, and also tracks through natural forest. Of 134 exotic weeds, 25 were classified as invasive species and the number of invasive species ranged from 8 to 15 per park. An assessment of the risk of invasive species was made for three national parks based on an invasive species assessment protocol. Examples of highly invasive species were Chromolaena odorata and Mimosa diplotricha in Cat Ba National Park (island evergreen secondary forest over limestone); Mimosa pigra, Panicum repens and Eichhornia crassipes in Tram Chim National Park (lowland wetland forest dominated by melaleuca); and C. odorata, Mikania micrantha and M. diplotricha in Son Tra Nature Conservation area (peninsula evergreen secondary forest). Strategies to monitor and manage invasive weeds in forests and national parks in Vietnam are outlined.

Biological invasions are among the most serious threats to ecosystems. The golden apple snail Pomacea canaliculata (Lamarck, 1822) is considered one of the top 100 worst invasive alien species in the world. These snails consume benthic primary producers, including submerged macrophytes, which may lead to an increase in nutrient concentration in the water, enhance growth of phytoplankton, and decrease growth of macrophytes, thereby shifting the primary production from benthic to pelagic habitats in shallow systems. To test this hypothesis, we conducted a short-term experiment with and without the invasive P. canaliculata in mesocosms with high abundance of the native submerged macrophyte Vallisneria natans (Lour.) Hara. Compared with snail-free control, the snail increased the concentrations of total nitrogen (TN), nitrate nitrogen (NO3−–N), total and organic suspended solids (TSS and OSS), decreased the concentrations of soluble reactive phosphorous (SRP), but had no effect on total phosphorus (TP) and the TN:TP ratio. In addition, the snails decreased the biomass, leaf length and tiller number of V. natans, and decreased light intensity. Although snail presence did not change the biomasses of nanophytoplankton and picophytoplankton, it did increase the biomass of microphytoplankton leading to an increase in total phytoplankton biomass. Our study shows that P. canaliculata shifted primary production from benthic to pelagic habitats, altered the phytoplankton community size structure, and decreased water quality. The results add further evidence of negative ecosystem impacts of this invasive apple snail and call for its control in invaded shallow lake ecosystems.

Invasive alien species and planetary and global health policy

Costs to Ecuador's rice sector during the first decade of an apple snail invasion and policy recommendations for regions at risk

Kruger National Park (KNP), South Africa, covers an area of 20,000 km2 and is one of the world’s most widely known protected areas. Like many protected areas, KNP is facing an increasing problem with the introduction and spread of alien plants. However, species prioritization using poor baseline data remains a key challenge for managers globally. Publications, expert opinion, and field observations indicate that 407 alien plant taxa have been recorded in the KNP; this list also included hybrids, ornamentals, records that could only be identified to the genus level, and extralimitals (i.e., species native elsewhere in South Africa; 22 species in total); in addition, two species are considered eradicated, and three potentially eradicated. Such extensive lists of poorly defined species’ statuses accumulated over long periods of time poses challenges to current decision-making processes. This is especially important for the management of naturalized (maintaining self-sustaining populations) and invasive species (subset of naturalized species that have spreading populations), because management needs to identify and target high-priority species and vulnerable sites. Here, we provide an up-to-date inventory of alien plant species that occur in natural areas in KNP (i.e., beyond tourist camps and other infrastructure) and thus represent a potential threat to the native species diversity in the park. We identified 146 such alien taxa, of which 30 are casuals, 58 are naturalized, 21 have become invasive, and for 37 species, the status remains to be determined. Twelve of the invasive species in KNP are globally widespread, occurring in more than 100 regions, and five (i.e., Pontederia crassipes, Lantana camara, Opuntia stricta, Chromolaena odorata and Mimosa pigra) are listed among 100 of the world’s worst invasive alien species. The alien flora in KNP comprises 41 families. Solanaceae (45.5%) and Asteraceae (26.1%) are over-represented among invasive species compared to non-invasive species. The alien flora of KNP mostly originates from North America and South America, and largely consists of perennials and herbaceous species. We found no significant results regarding the effect of origin and life span on invasion status. Despite a steady increase in the numbers of alien and naturalized plants since the 1980s, species we classified as invasive generally represent earlier introductions and have not increased substantially since the beginning of this century. Our paper highlights that carefully revised naturalized and invasive species lists reflecting the current situation in protected areas present a strong knowledge base for effective management strategies. In addition to addressing data gaps related to the distribution of alien species on a global scale, knowledge from large protected areas such as KNP contributes to understanding invasions in landscapes with varying and unique habitat types.

The apple snail, Pomacea canaliculata (Lamarck, 1819), a freshwater snail listed as a pernicious invasive alien species by the World Conservation Union (IUCN), has caused serious agricultural and ecological harm worldwide. This species has inflicted significant agricultural and ecological damage on a global scale. Under conditions of extreme environmental stress, the apple snail enters a state of dormancy and remains in this dormant phase until environmental conditions become favorable again, which serves as a crucial survival strategy. In our study, we subjected apple snails to 30 days of air-exposure stress followed by rehydration to reactivate them. Our objective was to elucidate the underlying mechanisms associated with drought tolerance, dormancy, and subsequent arousal based on transcriptomic analyses. The results indicated that the groups subjected to 5-, 15- and 30-day air-exposure stress treatments (DRY05, DRY15 and DRY30) exhibited a general down-regulation of metabolism-related pathways. These pathways included starch and sucrose metabolism, linoleic acid metabolism, glutathione metabolism and glycosaminoglycan degradation, compared with the control (CK). In addition, the weighted correlation network analysis (WGCNA) identified two critical pathways: toll-like receptor signaling pathway and adherens junction. The down-regulation of these pathways indicated a decrease in immune levels during dormancy in apple snails. This may further lead to the inhibition of apoptosis and a reduction in energy expenditure, thereby sustaining vital activities. The up-regulation of intercellular adhesion and immune-related pathways upon reawakening (RCY01) further substantiates the presence of this tolerance mechanism during dormancy in the apple snail. This study provides a reference for understanding the tolerance of apple snails to extreme environments, and provides a basic theory for apple snail biocontrol research.