Invasive Slug Research Articles

Discovery of the malacopathogenic nematode Pellioditis akhaldaba from the Caucasus in alien slugs in the Main Botanical Garden in Moscow

Summary A member of the genus Pellioditis Dougherty, 1953 (syn. Phasmarhabditis Andrássy, 1976) was detected in three introduced gastropod species in Moscow for the first time. Both the nematode and its gastropod hosts were found to have originated from the Caucasus region. No native gastropod species as well as the alien invasive slug Arion vulgaris were infected by P. akhaldaba. The Moscow strain of P. akhaldaba is very close to P. akhaldaba from Georgia in the ITS rDNA (7 bp difference) but they differ significantly in the sequences of COI mtDNA (50 bp difference). However, phylogenetic analysis of both loci showed that these two strains were the closest relative to all other species and strains of the genus Pellioditis studied.

Gastropod grazing on fresh and senescent leaves of non-native invasive plants Reynoutria japonica and Impatiensglandulifera

In invaded regions, the introduced non-native plants Reynoutria japonica and Impatiens glandulifera show little grazing damage, most likely due to the absence of specialized herbivores and the deterrent effect of secondary metabolites on generalist herbivores. The low degree of grazing damage has been explained by the non-mutually exclusive enemy-release and novel weapon hypotheses. We tested assumptions of these hypotheses by conducting a series of preference tests in which leaf samples from R. japonica, I. glandulifera, and the native Urtica dioica were offered to five species of generalist gastropods (the native Arianta arbustorum, Cepaea nemoralis and Fruticicola fruticum, and the non-native invasive Hygromia cinctella and Arion vulgaris). In addition, we determined the C/N-ratio and total phenolic compounds (as a surrogate of secondary metabolites) of the plant species. In the choice experiment with fresh leaf samples, all snail species showed a preference for U. dioica, with the exception of the non-native invasive slug A. vulgaris, which ate leaf tissue from I. gladulifera almost as much as from U. dioica. The snails’ preference of U. dioica was even more pronounced when the fresh weight of leaf material eaten was considered. No-choice tests with either fresh or dead R. japonica leaves showed that most individuals of all species ate small amounts of fresh leaves, but less of dead leaves. In contrast, no-choice tests with either fresh or senescent I. glandulifera leaf tissue showed that individuals of all five gastropod species consumed larger amounts of senescent leaves than fresh leaves, probably because secondary compounds have been broken down or leached or the leaf texture has changed. The low susceptibility of these non-native invasive plants to the gastropods can most likely be explained by a combination of chemical and physical plant characteristics.

Differences in field behavior between native gastropods and the fast-spreading invader Arion lusitanicus auct. non Mabille

Dispersal is a crucial process for population exchange and expansion, and traits that facilitate dispersal may be positively selected during biological invasions. Here, we performed a basic study on differences in behavior between the slug Arion lusitanicus auct. non MABILLE, 1868 (Gastropoda: Pulmonata), which is considered to be one of the 100 worst invasive species in Europe, and native gastropods. We assumed that the species is more active and less sensitive to otherwise aversive stimuli, and thus more likely to utilize novel environments. We quantified field densities and performed pitfall trap studies in 15 differently-structured habitats (urban, grassland, succession, riverine forest) in the floodplain of the LTER (Long Term Ecological Research) site ‘Rhine-Main-Observatory’ in Hesse, Germany. Here, A. lusitanicus was naturalized and scored 15 in terms of abundance rank, but was the dominant species in terms of trappability with the acidic Renner solution. A more detailed approach with a set of different baits showed that individuals of the invader were attracted to the acidic Renner solution, mustard oil, and garlic extract, all of which the native snails and slugs avoided. The results support the hypothesis that the invasive slug differs from other gastropods in its behavioral response to unusual, novel stimuli that may indicate some potential threat to other gastropod species. Future studies are needed to show if this behavior is related to personality traits such as exploration, boldness and risk-taking, and if it may have been positively selected in the context of the slug being passively spread in severely-transformed habitats such as gardens and greenhouses.

Egg-laying habitat selection of the invasive slug Krynickillus melanocephalus Kaleniczenko, 1851 (Gastropoda: Eupulmonata: Agriolimacidae)

Invasive slugs cause damage to biodiversity as well as to horticultural and agricultural crops. To develop methods to mitigate problems with recently emerging invasive species, basic ecological knowledge about them in their new environment is crucial. We investigated the egg-laying substrate preference of Krynickillus melanocephalus in a laboratory experiment in which the slugs could choose between four different substrates. Slugs were mainly observed in contact with birch leaf compost, and less so with gravel, potting soil and sphagnum moss. Almost 90% of the eggs were found buried in birch leaves, although eggs were found also in the other substrates. In addition, we tested the winter survival of the eggs by examining their susceptibility to low temperatures. Eggs subjected to freezing temperatures did not survive, and at 8 °C, 60–70% of the eggs hatched after three months (640 degree days). In areas where K. melanocephalus is present, transporting any soil, gravel or compost material could potentially contribute to spreading the species. Particularly, leaf composts may warrant attention in this areas.

Pellioditis pelhamensis n. sp. (Nematoda: Rhabditidae) and Pellioditis pellio (Schneider, 1866), earthworm associates from different subclades within Pellioditis (syn. Phasmarhabditis Andrássy, 1976).

Recently, much attention has been focused on a group of rhabditid nematodes called Phasmarhabditis, a junior synonym of Pellioditis, as a promising source of biocontrol agents for invasive slugs. Pellioditis pelhamensis n. sp. was first isolated from earthworms near Pelham Bay Park in Bronx, New York, USA, in 1990 and has been found to be pathogenic to slugs as well as some earthworms. It has also been used in several comparative developmental studies. Here, we provide a description of this species, as well as a redescription of a similar earthworm-associated nematode, Pellioditis pellio Schneider, 1866, re-isolated from the type locality. Although P. pelhamensis n. sp. and P. pellio are morphologically similar, they are reproductively isolated. Molecular phylogenetic analysis places both species in a clade that includes all species previously described as Phasmarhabditis which are associated with gastropods. Phasmarhabditis Andrássy, 1976 is therefore a junior synonym of Pellioditis Dougherty, 1953. Also, Pellioditis bohemica Nermut', Půža, Mekete & Mráček, 2017, described to be a facultative parasite of slugs, is found to be a junior synonym of Pellioditis pellio (Schneider, 1866), adding to evidence that P. pellio is associated with both slugs and earthworms. The earthworm-associated species P. pelhamensis n. sp. and P. pellio represent different subclades within Pellioditis, suggesting that Pellioditis species in general have a broader host range than just slugs. Because of this, caution is warranted in using these species as biological control agents until more is understood about their ecology.

The PPAR-γ Agonist Pioglitazone Modulates Proliferation and Migration in HUVEC, HAOSMC and Human Arteriovenous Fistula-Derived Cells.

The failure of arteriovenous fistulas (AVFs) following intimal hyperplasia (IH) increases morbidity and mortality rates in patients undergoing hemodialysis for chronic kidney disease. The peroxisome-proliferator associated receptor (PPAR-γ) may be a therapeutic target in IH regulation. In the present study, we investigated PPAR-γ expression and tested the effect of pioglitazone, a PPAR-γ agonist, in different cell types involved in IH. As cell models, we used Human Endothelial Umbilical Vein Cells (HUVEC), Human Aortic Smooth Muscle Cells (HAOSMC), and AVF cells (AVFCs) isolated from (i) normal veins collected at the first AVF establishment (T0), and (ii) failed AVF with IH (T1). PPAR-γ was downregulated in AVF T1 tissues and cells, in comparison to T0 group. HUVEC, HAOSMC, and AVFC (T0 and T1) proliferation and migration were analyzed after pioglitazone administration, alone or in combination with the PPAR-γ inhibitor, GW9662. Pioglitazone negatively regulated HUVEC and HAOSMC proliferation and migration. The effect was antagonized by GW9662. These data were confirmed in AVFCs T1, where pioglitazone induced PPAR-γ expression and downregulated the invasive genes SLUG, MMP-9, and VIMENTIN. In summary, PPAR-γ modulation may represent a promising strategy to reduce the AVF failure risk by modulating cell proliferation and migration.

Historical forest disturbance results in variation in functional resilience of seed dispersal mutualisms.

Mutualistic interactions provide essential ecosystem functions that contribute to promoting and maintaining diversity in ecosystems. Understanding if functionally important mutualisms are "resilient" (i.e., able to resist or recover) to anthropogenic disturbance is essential for revealing the capacity for diversity to recover. Animal-mediated seed dispersal supports plant population growth and influences community structure, and disturbance affecting seed dispersal can contribute to low resiliency of plant diversity. Ant-seed dispersal mutualisms are sensitive to anthropogenic disturbance, as they rely on one to a few high-quality dispersal partners. In North American eastern deciduous forests, ants in the genus Aphaenogaster are "keystone dispersers" of understory forbs adapted to dispersal by ants (myrmecochores), which make up more than one-third of the understory herbaceous community. The majority of forests within this region have regenerated from previous disturbance in the form of clearing for agriculture. Previous studies have revealed that myrmecochore diversity is not resilient to previous clearing. Here, we ask if seed dispersal mutualisms are resilient to historical forest disturbance and if decreases in mutualistic interactions with partners, Aphaenogaster sp., or increases in antagonistic interactions cause degradation of function. In a large-scale natural experiment (20 sites), we measured seed removal, the abundance of mutualistic partners and other invertebrates interacting with seeds, myrmecochore cover, and diversity, along with ant habitat and forest structure. We found lower and more variable seed removal in secondary forests compared with remnant forests. A path analysis of all forests revealed that the abundance of mutualists was the primary determinant of the variation in seed removal, and that seed damage by antagonists (invasive slugs) negatively affected dispersal and was higher in secondary forests. In a path analysis of remnant forests, the link between mutualist abundance and seed removal was absent, but present in the secondary forest path, suggesting that seed dispersal is more variable and dependent on the mutualist abundance in secondary forests and is stable and high in remnant forests. Our results suggest that functional resilience to disturbance is variable, where seed dispersal is low in some secondary forests and not others. This work provides key insights into the effects of disturbance on mutualistic interactions and how the resilience of critical ecosystem functions impacts the capacity for diversity resiliency.

Expansion of the invasive Balkan slug Tandonia kusceri (Stylommatophora: Milacidae): A new frontier in northern Ukraine and other new records

The distribution of the invasive slug Tandonia kusceri is reviewed and mapped with our new findings and previously unpublished recent reports based on photographs from citizen science databases (iNaturalist, UkrBIN). Two new colonies of T. kusceri were found and monitored in Kyiv city (Northern Ukraine) during the 2021–2022. These colonies are about 350 km north from the nearest previously published records of this species, as well as any other species of Milacidae in Eastern Europe. The slugs inhabit the urban open and semi-open landscapes of Kyiv city together with several other invasive molluscs, in one locality notably together with Oxychilus translucidus, Harmozica ravergiensis and Xerolenta obvia. One specimen of T. kusceri was found in a basement of a private estate in Radyvyliv town (Rivne region, Northern Ukraine) in 2020, but it is unknown whether it represents an established colony. Previously unpublished reports of T. kusceri on iNaturalist include two reliable findings from the Caucasian region, in Georgia and Russia, both in 2021. These are the first reports of any Tandonia in Caucasus, as well as in the mentioned countries, with one in Georgia being the eastmost frontier for this genus. In addition to a previously published 2013 report of T. kusceri near Chicago, USA, there are multiple iNaturalist reports of this slug in southern Ontario, Canada (600 km east of Chicago), starting from 2017. Moreover, there are several new reports of T. kusceri in Ukraine, including Kherson, Dnipro, Kryvyi Rig, Marhanets and Kamianets-Podilskyi cities. Considering that most of our new T. kusceri records are from the 2020s, it is most likely that slug has invaded these regions very recently and is still continuing to expand northward and eastward in Europe. This species is expected to further extend its range both in Europe and North America.

The marsh slug, Deroceras laeve in Darjeeling Himalayas, India: First record and modelling of suitable habitats

Invasive slugs are a menace from the agricultural point of view apart from the impact on the native biota and the ecosystems. Subsequent to the observations of the marsh slug, Deroceras laeve in West Bengal, India, an attempt was made to confirm the species identity and the species distribution modelling considering the Himalayas of West Bengal and adjacent regions as the geographical distribution of the species. Assessment of the DNA barcoding of the COI gene confirmed the species as D. laeve with 99.84% similarity with a specimen of Canada. Owing to its record from the concerned regions, the prospective spread and the invasion of the species in similar regions were modelled using Maxent species distribution modelling. The result of species distribution modelling indicated that precipitation seasonality, precipitation of the driest month, snow coverage, elevation, and herbaceous vegetation had the most influence on the occurrence of D. laeve. The possible spread of the species can be expected in the future if congenial conditions are available in the extended geographical regions. As an invasive species, D. laeve may affect agricultural productivity apart from altering the habitat conditions and imposing competitive interactions with the native species. Based on the present observation, appropriate strategies may be framed for monitoring and regulating the spread of the invasive slug.

Distribution of Phasmarhabditis (Nematode: Rhabditidae) and Their Gastropod Hosts in California Plant Nurseries and Garden Centers.

Three species of Phasmarhabditis were recovered from 75 nurseries and garden centers in 28 counties in California during fall and winter 2012–2021. A total of 18 mollusk species were recovered, most of them invasive. Nematodes were identified by sequencing the D2-D3 expansion segments of the large subunit (LSU or 28S) rRNA. Based on these surveys, P. californica was the most widespread species (37 isolates, 53.6% recovery); followed by P. hermaphrodita (26 isolates; 37.7% recovery); P. papillosa and a closely related P. papillosa isolate (6 isolates; 8.7% recovery). Nematode isolates were mainly collected from four invasive slugs (Deroceras reticulatum, D. laeve, Arion hortensis agg, Ambigolimax valentianus) and snails (Oxychilus spp. and Discus spp.). Results suggest that P. californica and P. hermaphrodita share an ecological niche in Northern, Central, Coastal, and Southern California, north of Los Angeles County.

Phasmarhabditis thesamica n. sp. (Nematoda: Rhabditidae), a new slug nematode from southern slope of Caucasus, Georgia

Summary Phasmarhabditis thesamica n. sp., belonging to the family Rhabditidae, was isolated from the bodies of the invasive slug, Deroceras reticulatum in Georgia. Nematodes of this genus have never been recorded previously in Georgia. Phasmarhabditis thesamica n. sp. was characterised at morphological, morphometrical and molecular level. Females are 2052 (1863-2241) μm long, lateral fields consisting of three protruding central ridges and four incisions. The vulval opening is in the middle of the body. The tail is conical, long, tapering to a filiform tip, with prominent rod-shaped phasmids. The reproductive system is didelphic-amphidelphic. Males are 1301 (1123-1456) μm long, with an open peloderal bursa, which is supported by nine pairs of genital papillae 1 + 1 + 1/2 + 1 + 3, and two phasmids located close to tail tip. The molecular phylogeny of P. thesamica n. sp. inferred by using ITS, D2-D3 expansion domains of the 28S rRNA gene and the 18S rRNA gene revealed close relationships with P. clausiliiae, with high support.

A lesson for planning rodent eradications: interference of invasive slugs during the Gough Island mouse eradication attempt in 2021

Context House mice (Mus musculus) are the main drivers of biodiversity declines on Gough Island (6500 ha; 40°21′S, 009°53′W), central South Atlantic. A mouse eradication operation was planned, the largest global attempt targeting only this species. Understanding and managing challenges of operating at such scales are crucial for maximising the chance of eradication success. The Gough Island mouse eradication attempt was implemented between June and August 2021, after years of planning and trials. We expected poor weather and negligible non-target bait consumption. Aims We aimed to assess the impact of expected and unexpected challenges faced during the eradication operation on Gough Island, namely poor weather and rapid bait disappearance. Methods We set up bait degradation plots across the primary habitats to monitor the impact of expected heavy rain on bait pellets. In contrast, bait availability monitoring and slug laboratory trials were set up ad hoc in response to unexpected observations of high bait consumption by invasive slugs in the lowlands, where both slugs and mice are more abundant. Key results Bait degradation rates were very different between the highlands and the lowlands, with bait in the highlands lasting about six times longer, despite bait pellets receiving more precipitation and the highlands being persistently under cloud. Bait availability in the lowlands dropped by >80% within a few days of the second and third bait application, down to critically low levels (~2 kg ha−1). Importantly, mouse activity was negligible by this time. Non-native slugs appeared to be the main cause of such a sudden drop in rodent bait availability. Conclusions The expected rainy weather was not a significant direct cause of bait degradation in the short term. In contrast, the unexpected slug interference, overlooked in earlier planning trials, resulted in major adjustments of the baiting strategy. Indeed, the rapid bait disappearance in the lowlands triggered the third bait application over this area, at a higher rate. This was not enough, as mice are still present. Implications This is the first report of slug interference during aerial rodent eradications. Our results illustrate how interference by non-target species could affect future pest eradications using baits and should, as far as possible, be assessed early during planning.

Feeding habits of the exotic invasive slug Limax maximus: a basis for risk assessment of herbivory on forest and agricultural ecosystems

Feeding habits of the exotic invasive slug Limax maximus: a basis for risk assessment of herbivory on forest and agricultural ecosystems

Citric Acid As a Potential Molluscicide and Deterrent for the Invasive Slug Arion fasciatus

We investigated citric acid as a potential molluscicide and deterrent for the invasive slug species Arion fasciatus (Nilsson, 1823). To examine the efficacy of citric acid through ingestion or environmental exposure, slugs were given lettuce sprayed with 5% citric acid or 5% citric acid sprayed paper towels in no-choice tests. Slugs in choice tests were given both Romaine lettuce sprayed with 5% citric acid and DI water. We also investigated the impact of spraying Romaine lettuce seedlings with 5% citric acid to see if it impacts plant growth. No-choice tests revealed that environmental exposure to citric acid resulted in the eventual death of 64% of the slugs in the treatment group, while the ingestion of citric acid did not affect slug mortality. Choice tests revealed that citric acid significantly decreased Romaine lettuce herbivory. Romaine lettuce seedlings that were sprayed weekly for six weeks with 5% citric acid had a 31% lower biomass compared to the control, but no seedling deaths were observed. Overall, citric acid shows promise as a slug deterrent and molluscicide, though greenhouse and field trials are required to further elucidate its efficacy and impact on plants.

Bioactive Modified Non-Wovens as a Novel Approach of Plants Protection against Invasive Slugs

Invasive slugs generate significant problems in the area of horticultural and agricultural production. Despite the multitude of methods to reduce the pest population, including preventive, mechanical, agrotechnical, cultivation, biological, and chemical treatments, no effective plant protection strategy has been developed so far. In this paper, a solution based on modified non-woven fabric with bioactive molluscicidal properties using the extract of tansy flower, metaldehyde, and abamectin (Vertigo® 018 EC) was proposed. All modified mats show significant anti-slug properties in comparison to control, and molluscicidal properties depend on the type of active substance. Non-woven modified with commonly used metaldehyde demonstrated fast action against slugs and presents the highest efficiency. The effectiveness of non-woven mats with Vertigo® 018 EC is lower than for the mats with metaldehyde but higher than for the mats modified with tansy flower extract. The proposed solution will enable removing and neutralization of molluscicide from the fields, after the efficient pest control, according to circular economy principles. Moreover, it may allow for better control of the molluscicide release to the environment in comparison to widely used pellets, and contribute to the virtual protection of plants against invasive slugs.

Occurrence of an invasive slug <i>Limacus flavus </i>(Stylommatophora: Limacidae) in the trees of an urban landscape in Kyiv city (Ukraine), with remarks on its colouration

The importance of trees for an invasive Mediterranean cellar slug, Limacus flavus , was studied within one block of a residential area in Kyiv city (Central Ukraine) from spring of 2020 to spring of 2021. Slugs tended to occur in the old poplars ( Populus nigra var. italica ). Live animals or their traces were found on the 71 of 320 poplars and on 17 trees of other species in the studied area. Slugs often go up to at least 12 m above the ground on these poplars and feed on the lichens there. Animals breed and spend the daytime inside at least some of these trees under the bark. Slugs were wintering in some of these trees in 2020-2021 and probably also at least in 2019-2020, while previously L. flavus was reported from Eastern Europe only in connection to cellars, basements and greenhouses. Apparently these slugs are occupying additional habitats in response to climate change and their occurrence in the trees may become common in Eastern Europe with the warming of climate. The colouration of L. flavus and closely related L. maculatus is discussed. Various differences of the colouration were suggested in the literature to distinguish the two species, most notably the central light stripe on the back of L. flavus , but this character is absent in most of the studied specimens and, therefore, the overall colouration overlaps in the studied populations of the two species.

Experimental indications of gardeners' anecdotes that snails interfere with invasive slugs.

The invasive Spanish slug (Arion vulgaris) is an important pest species in agriculture and horticulture in Europe. In the last decades it has spread across the continent where it outcompetes native slug and snail species, thus posing a threat for biodiversity. A popular anecdote suggests to promote Roman snails (Helix pomatia) in gardens because they are able to control A. vulgaris. We examined a potential interrelationship between these two species using a mesocosm experiment with lettuce plants. 13C-15N stable isotope labelling of lettuce allowed us to investigate interactions between Helix and Arion on weight gain/loss and herbivory. Additionally, we wanted to know whether different watering regimes (daily vs. every 3rd day watering of weekly amount) and earthworms alter these interactions. Egg predation of Helix on Arion eggs was further tested in a food-choice experiment. Arion showed a five times higher herbivory per body mass than Helix in a single-species setting. However, in mesocosms containing both species percentage of herbivory per body mass was significantly lower than in Arion-only mesocosms, especially when watered every three days. Overall isotope uptake via eaten lettuce was unaffected by the presence of the other species. Only very little predation (three out of 200 eggs) of Helix on Arion eggs was observed. Our results provide no evidence for a clear dismissal or confirmation of the popular gardener’s anecdote that Helix snails have a negative effect on Arion abundance or herbivory.

Fermenting Bread Dough as a Cheap, Effective, Nontoxic, and Generic Attractant for Pest Snails and Slugs.

Simple SummarySnails and slugs are key pests of crops but control options are limited with an overreliance on molluscicides, which have variable efficacy. Thus, there is an urgent need to improve the performance of these pesticides, and one option is to identify more efficacious attractants for incorporation into baits and/or use in traps. Our results showed that a simple bread dough (flour, water, and yeast) was highly attractive to six invasive pest gastropod species in both laboratory and field trials in Hawaii, Oregon, and Montana. The dough remained attractive for at least 8 days and was significantly more attractive than a widely used toxic bait (Deadline® M-Ps™). Given its simplicity, low cost, and the ready availability of its ingredients, the dough has potential to be used in developing countries where access to commercial molluscicides is limited by cost. In addition, a premixed dry formulation of flour and yeast, where water simply needs to be added to activate the bait, would likely have an indefinite shelf life and be readily shippable, both highly desirable properties for an operational lure. Thus, bread dough constitutes a nontoxic, generic, and effective tool that could be used in the detection and management of pest gastropods worldwide.Invasive slugs and snails are among the most damaging pests of agriculture in temperate and tropical regions of the world. Control options, however, are limited and there is a heavy reliance on chemical molluscicides of variable efficacy. There is an ongoing need to improve management methods. Here, we show that a simple fermenting bread dough formulation (flour, water, and yeast) was effective in attracting pest mollusk species in laboratory tests, and in multiple replicated field trials in Hawaii, Oregon, and Montana. The dough attracted substantially more terrestrial pest gastropods, including invasive species of major economic importance such as Cornu aspersum, Deroceras reticulatum, Ambigolimax valentianus, Xerolenta obvia, Lissachatina fulica, and Parmarion martensi, than water controls. The dough remained attractive for at least 8 days and was significantly more attractive than a widely used metaldehyde-based bait, Deadline® M-Ps™. Thus, fermenting bread dough represents a nontoxic, generic, and effective tool to aid in managing pest gastropod infestations, either using baited traps or in attract-and-kill approaches. Given its simplicity, low cost, and the ready availability of its ingredients, the dough also has potential to be used in developing countries where access to commercial molluscicide baits is limited by cost.

Antagonistic and mutualistic interactions alter seed dispersal of understory plants at forest edges

AbstractSeed dispersal by ants is an important interaction in North American eastern deciduous forests, where 30–40% of understory plants are myrmecochores, with seeds that possess lipid‐rich appendages (elaiosomes) that attract seed‐dispersing ants. Contemporary forests are fragmented and have regenerated from being previously cleared (secondary forests). In secondary forests, and especially along edges, myrmecochores are a depauperate component of forests. Here, we assess if seed dispersal of myrmecochores by ants, particularly the keystone disperser, Aphaenogaster sp., is intact in forest interiors compared to edges. In three North American northeastern deciduous forests, we compared myrmecochore cover and richness, seed dispersal by ants, and the abundance and richness of ants and other forest floor invertebrates between interiors and edges. We also conducted a seed removal experiment, excluding either ants, rodents (seed predators), or ants and rodents, to test their effects on seed dispersal between interiors and edges. We found differences in the composition of understory plants between interiors and edges, with edges lacking myrmecochores. We also found that seed dispersal by ants was lower in two of the three edges and corresponded to Aphaenogaster sp. abundance. Antagonistic interactions with an invasive slug that is an elaiosome robber, Arion subfuscus, was more apparent than damage by rodents in the experiment, negatively affected dispersal by ants more at edges than in interiors. Here we show that changes in mutualistic and antagonistic interactions affect seed dispersal at forest edges and that not all forest edges are the same, with some more intact than others. Understanding how seed dispersal is impacted in contemporary forests is important towards the goal of conserving and restoring depauperate forest understory communities.

Occurrence in Mexico of two European invasive slug species: Arion vulgaris Moquin-Tandon, 1855 and Arion intermedius (Norman, 1852)

Occurrence in Mexico of two European invasive slug species: Arion vulgaris Moquin-Tandon, 1855 and Arion intermedius (Norman, 1852)