Tag Archives: invasive species

A narrow escape?

Earlier this week I received some pictures from Gerard van Buurt (Willemstad, Curacao) showing a guave fruit brought to him with snails. The fruit came from a local supermarket. If he could possibly tell what snails they were? Van Buurt is a retired official of the Department of Agriculture on the island, and I have been in contact with him for quite some years.

The hunch was they were Succineidae, but he had no clue what species. As the sticker on the fruit indicated it was imported from the U.S.A., I contacted the owner of the supermarket chain who happened to reside in the Netherlands. To cut a long story short, the fruit came from Florida and was not only available in two shops on Curacao, but also on Aruba and Bonaire where the same chain also has shops. Alarmed by our inquiry the local manager had the fruits removed and checked.

Snails on Guava fruit 8976

Knowing that the suspected source was in the U.S.A., colleagues from USDA/APHIS were contacted for more information. They confirmed that the species is Calcisuccinea campestris (Say, 1818), which is known to be a pest species of fruit and horticultural crops. The risk of potential establishment of this species is one not worth taking.

Feeding this information back to Curacao, the danger of an unintentional introduction of yet another alien species in the Curacao malacofauna was fenced off thanks to an unknown attentive buyer of the infected fruit. Although this was a narrow escape, it is yet another example of how relatively easy it is to introduce snails via commercial activities to places where they don’t belong and can be harmful.

The concerted action of Gerard van Buurt (Curacao) and Francisco Borrero (USDA) is thankfully acknowledged.

Non-native South American species

An extensive analysis just appeared from Darrigan et al. (advance online) about the occurrence of non-native molluscs throughout South America. Their abstract is “Non-native species have been introduced at escalating rates during the last decades, mainly due to the dispersion generated by the increasing trade and transport worldwide. Mollusks, the second largest metazoan phylum in terms of species richness, are no exception to this pattern, but, to date, a comprehensive synthesis of non-native mollusk species (NNMS) in South America was not available. For this purpose, an e-discussion group was formed with malacologists and taxonomists from South America, where we exchanged and analyzed bibliography, databases and information about NNMS, providing expert opinion to this assessment. The first list of non-native mollusk species for South America, considering terrestrial, freshwater and marine environments, includes 86 NNMS distributed in 152 ecoregions (terrestrial, freshwater and marine) of the 189 recognized for the South American continent. Information on their native region, vectors, first record for South America and distribution, are also provided. In the analysis of the distribution of the NNMS and the entry points of each species (e.g., ports, cargo and passenger airports, cities) and status of conservation of the ecoregions, four hot spots were recognized: Subtropical-Atlantic, Northern Andes, Central Andes and Southern Andes. This work, thus, sets the baseline on NNMS for South America, a key piece of information regarding the development of policies targeting the management of biological invasions and their socio-ecological impacts“.

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An interesting study that was totally done by South American malacologists. The paper contains a number of graphs and figures that illustrates the rapid increase over the past decades of non-native species in this understudied continent. It will be a good basis for further studies.

Darrigan, G. et al., 2020. Non-native mollusks throughout South America: emergent patterns in an understudied continent. – Biological Invasions (advance online): 19 pp. https://doi.org/10.1007/s10530-019-02178-4.

Ovachlamys in Brazil

Just published: a report that confirms the occurrence of a new invasive snail in this country. “The occurrence of the invasive non-native Asiatic jumping land snail Helicarionidae Ovachlamys fulgens (Gude, 1900) is finally confirmed by us in the southern Brazil region, specifically on the Santa Catarina State territory, from previous records available since the year 2013 “masked” under the identity of another species. This report increases to 27 the number of exotic continental molluscs confirmed in the State of Santa Catarina/ SC.“.

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Not surprisingly the occurrences are mainly situated near the region where the port activities occur. I wouldn’t be surprised if these snail travel with sea containers, as the distribution of Bulimulus sp. suggests (ongoing research, unpublished data).

Aguda-Padron, I., 2019. Confirmed occurrence of the invasive asiatic jumping land microsnail Helicarionidae Ovachlamys fulgens (Gude, 1900) in the Southern Brazil region. – Bioma (El Salvador) 5 (49): 11–15.

Achatina in Ecuador

Earlier this year a paper by Cuasapaz-Sarabia & Salas presented results about the occurrence of Achatina fulica in a private nature reserve. “Achatina fulica is an invasive terrestrial gastropod known as one of the 100 most harmful invasive species in the world. Achatina fulica is known in Ecuador since 2008, but the impact over their native ecosystems has not evaluated. The main objective was to determine the home range (HR) of this species in two zones with different levels of intervention in the Cerro Blanco reserve. The field work consisted in the capture, marking, recapture, taking of morphometric measurements and georeferencing of the individuals; for the analysis of data, HR was calculated using the convex polygon method, and environmental variables were correlated through a principal component analysis (PCA). The average HR in the altered zone was 3.58 m2 (± 0.93, n = 30), and on the ecotourist trail was 3.27 m2 (± 0.48, n = 40); the humidity was the environmental parameter that directly influences the life area and the population density in both zones study. The management of this invasive species does not appear as a key management issue for this private reserve, so it is recommended a control actions for its eradication“.

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It is remarkable that – although the occurrence of this species in Ecuador is known for more than 10 years – eradication programs seem to be lagging behind. And even (private) nature reserves are not alarmed about it. Thus the risk of spread of this important pest species is still prevalent. A serious issue…

Cuasapaz-Sarabia, J. & Salas, J.A., 2019. Área de vida de la especie invasora Achatina fulica (Gastropoda: Achatinidae) en un área de conservación de bosque seco ecuatoriano. Revista peruana de biología 26(1): 41 – 48.

Naesiotus in Spain

The globalisation of snails has taken a next step: Ramos Sánchez et al. just published a first record of a Bulimulidae species in Europe.

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Their abstract reads: “In the this article, the presence of a Bulimulidae species, classified as Naesiotus quitensis (Pfeiffer, 1848), is reported from an urban park in Madrid (Spain). This is the first citation of a species of this highly diversified Neotropical gastropod family in Europe. The species seems established in the park, but the ways of its introduction are unknown”.

Although it is a very slow process, the introduction of alien species in other ecological realms is clearly the consequence of human interventions, one way or the other. Hence there is little doubt that this introduction was a human act. We can only hope that the Spanish authorities will at least take monitoring actions.

Ramos Sánchez, J.M. et al., 2018. First citation for an exotic Bulimulidae species in Europe. Folia conchyliologica, 47: 11-14.

Ruminia decollata in Cordoba

Reyna & Gordillo just published a brief research note in which they report the finding of specimens of Ruminia decollata (Linnaeus, 1758) in Córdoba Province, Argentina.

According to these authors this snail is a potential host of roundworms that are common in dogs and cats, and thus may also affect susceptible humans. Moreover, this alien species may affect crops and horticultural products.

Reyna, P. & Gordillo, S., 2018. First report of the non-native snail Rumina decollata (Linnaeus, 1758) (Subulinidae: Gastropoda) in Córdoba (Argentina): implications for biodiversity and human health. – American Malacological Bulletin, 36 (1): 150-152.

Newly introduced snail

Agudo-Padrón is a frequent author of news about the southern Brazilian malacofauna. This time he published about a new introduction of a species from Asia, which he identified as Macrochlamys cf. indica (Benson, 1832).

This record was published in a new online journal from the University of El Salvador, named ‘Minerva’; a name which is already applied by at least 2 other journals and thus may be considered as a junior homonym 🙂

Agudo-Padrón, I & Souza da Luz, J., 2018 (‘2017’). Primer record confirmado de ocurrencia de un Caracol terrestre indo-asiático en Brasil y las Américas. – Revista Minerva, El Salvador, 1: 19-27.

A ritual link to snail invaders

Vazquez et al. (2017) recently published interesting research related to invasions. Their abstract reads as follows “The giant African snail, Lissachatina fulica, is considered one of the most invasive species worldwide, acting as a crop pest and diseases vector. It was first detected in Cuba in 2014 and is dispersing throughout Havana. We mapped 34 sites in the vicinity of Havana to assess its spread and analysed ecological (forestation and humidity) and anthropogenic (pollution and religious sites) factors in relation to the presence/absence of the snails using multivariate correspondence analysis. There were 14 sites at which the snail was present and where religious rituals of the Yoruba creed, an African rooted religion, were observed. No other variables showed significant relationships. This indicates that the rituals may be a major factor in the dispersal of the snail in Havana and more widely in Cuba. In light of this an outreach program with key Yoruba leaders may help in slowing the dispersal of the snail within Cuba, once the threats posed by this species are known”.

Reading through their paper I noticed that there may be also a ritual origin of the introduction of this snail in Florida, while there are indications that something similar maybe at stake in Brazil. Perhaps time for an ethnobiological approach complementary to the usual eradication schemes? Eradication without taking the driving force away behind the spread of this snail may simply not be sufficient.

Vazquez, A.,  Sanchez, J., Martinez, E. & Alba, A., 2017. Facilitated invasion of an overseas invader: human mediated settlement and expansion of the giant African snail, Lissachatina fulica, in Cuba. – Biological Invasions, 19 (1):1-4.

Achatina fulica east of Andes in Ecuador

Goldyn et al. have just published a paper of which the abstract reads “[w]e are reporting the first locality of invasive giant African snail, Achatina (Lissachatina) fulica (Férussac, 1821) in the Ecuadorian Amazon. It was found present in 32 out of 50 urban sites studied. The abundance where present was relatively high when compared to literature from other parts of the world. The snails were found in aggregations, usually foraging — most often on dogs’ feces. Statistical analysis suggests a preference toward this source of alimentation. This is the first report of such preference in this species, which is highly significant considering the possible implications. Besides the threat posed by an invasive species to the invaluable ecosystems of the Amazon, the pathogens transferred by A. fulica combined with a high abundance of the species in an urban environment and its food preferences may constitute an important health hazard for local human populations”.

This is, however, not the first published occurrence east of the Andes in Ecuador. The same authors have published this, and additional data, before in Folia Malacologica last year. If not an oversight by the reviewers and editor, this so-called “first locality” has to be blamed to the authors.

But the fact as such (if we exclude the many Brazilian occurrences), unfortunately, was waiting just to happen. Hopefully the Ecuadorian authorities nowadays know how they should eradicate this pest before it becomes wide-spread in this area which contain many endemic species.

Goldyn, B., et al., 2017. Urban ecology of invasive giant African snail Achatina fulica (Férussac) (Gastropoda: Achatinidae) on its first recorded sites in the Ecuadorian Amazon. – American Malacological Bulletin, 35: 59-64.

Genetics of invasive Cornu

Another paper on invasive species, i.e. Cornu aspersum in Chile, is entirely devoted to genetics. It was recently published by Nespolo et al. (2014).


The summary of this paper comprises seven items:
1. The distribution of additive vs. non-additive genetic variation in natural populations represents a central topic of research in evolutionary/organismal biology. For evolutionary physiologists, functional or whole-animal performance traits (‘physiological traits’) are frequently studied assuming they are heritable and variable in populations.
2. Physiological traits of evolutionary relevance are those functional capacities measured at the whole-organism level, with a potential impact on fitness. They can be classified as capacities (or performances) or costs, the former being directly correlated with fitness and the latter being inversely correlated with fitness (usually assumed as constraints).
3. In spite of their obvious adaptive significance, the additive genetic variation in physiological traits, and its relative contribution to phenotypic variance (or narrow-sense heritability) in comparison with maternal, dominance or epistatic variance, is known only for a few groups such as insects and mammals.
4. In this study, we assessed the additive and maternal/non-additive genetic variation in a suite of physiological and morphological traits in populations of the land snail Cornu aspersum.
5. Except for dehydration rate (h2 = 0.32 +/- 0.15), egg mass (h2 = 0.82 +/- 0.30) and hatchling mass (h2 = 1.01 +/- 0.31; population = fixed effect), we found very low additive genetic variation. Large non-additive/maternal effects were found in all traits. Cage effects did not change the results, indicating low contribution of common environmental variance to our results. No differences were found between the phenotypic and non-additive genetic variance/covariance matrices.
6. Even though we compared populations across 1300 km in a common garden set-up, our results suggest an absence of physiological as well as morphological differentiation in these populations.
7. These results contrast with previous analyses in the original distributional range of this species, which found high additive genetic variation in morphological traits. These are intriguing results demanding further quantitative genetic studies in the original distributional range of this species as well as the history of colonization of this invasive species.

Especially items 6 and 7 are interesting. Suppose we may see some time a follow-up by these authors.


Nespolo, R.F., Bartheld, J.F., González, A., Bruning, A., Roff, D.A., Bacigalupe, L.D. & Gaitan-Espitia, J.D., 2014. The quantitative genetics of physiological and morphological traits in an invasive terrestrial snail: additive vs. non-additive genetic variation. – Functional Ecology 28 (3): 682-692.