Tag Archives: Achatina fulica

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.

Reference:
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.

Interaction between alien and native species

Mirando & Pecora (2017) published an ecological study on the interaction between a native and an introduced species. “The Giant African Snail Achatina fulica is widely considered one of the most invasive species in the world. Megalobulimus paranaguensis is a snail endemic to the Brazilian Atlantic Rainforest. Data on possible interactions between A. fulica and terrestrial mollusc species are scarce. We tested whether the presence of A. fulica affects the behaviour of M. paranaguensis. We put three individuals of A. fulica and three individuals of M. paranaguensis in the same aquarium and quantified the time spent in seven behaviours, during three nights (n = 72 individuals for A. fulica and M. paranaguensis). We also tested the effect of sexual maturity, putting juvenile and adult individuals of both species in the same aquarium. We found behavioural differences between species, among individuals exposed to interspecific interactions and in interactions between these factors, but there was no difference in behaviour between juveniles and adults in the same species and between species. Achatina fulica changed its behaviour in interspecific interaction, becoming more active than usual, but M. paranaguensis did not change its behaviour in the presence of the alien species. Our results show that interspecific interaction has an effect on the behavioural patterns of the alien species, and the main factor negatively impacting Megalobulimus populations in Brazil is probably the non-specific control of A. fulica and the alteration and destruction of its habitats”.

This kind of studies, still rarely done, may become more important with the spread of introduced species (unfortunately too often happening). The study will be especially appealing to ecologists and conservationists.

Reference:
Miranda, M. & Pecora, I., 2017. Conservation implications of behavioural interactions between the Giant  African Snail and a Native Brazilian species. – Ethology Ecology and Evolution, 29 (3): 209-217.

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.

Reference:
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.

Achatina widespread in Ecuador

Several years ago the first introduction was reported of Achatina fulica in Ecuador. Goldyn et al. (2016) now have made a survey of its occurrence in the country, where it appears to be widespread.

schermafbeelding-2016-11-01-om-06-58-28

“Distribution data on Achatina fulica Bowdich were obtained from pest control agencies and from a survey of potential localities randomly distributed in all provinces of Ecuador. Among the total of 1,236 localities, 1,065 (86.2%) held populations of the species. The snail was found to spread much faster than predicted and was present in areas not previously suspected to be under the risk of invasion. The most endangered and infested areas were the coastal and Amazonian regions of the country. According to the pest control reports from government agencies, A. fulica most often affected plantations of cocoa (24.8% of localities), plantain (11.8%) and banana (11.2%), but was also known to forage on 56 other species of cultivated plants. The survey of likely habitats in random localities showed a high infestation rate; urban and ruderal sites turned out to be important but largely neglected dispersal hotspots for the species. Regular observations on two populations in the city of Puyo (Pastaza province, Amazonia) showed that the growth rate and population density were high: reaching adult size took on average four weeks”.

Reference:
Goldyn, B. et al., 2016. Notes on the distribution and invasion potential of Achatina fulica Bowdich, 1822 (Gastropoda: Pulmonata: Achatinidae) in Ecuador. – Folia Malacologica, 24 (2):85–90.

Population structure Megalobulimus

Miranda et al. (2015) published (advanced online) a paper dealing with two Megalobulimus species. Their abstract reads as follows: “Native Megalobulimus paranaguensis was identified on Brazil’s Ilha Porchat promontory, an area that Achatina fulica commonly populates. The population structures of these species were investigated for interactions. Spatial distribution, niche overlap and mark–recapture analysis were conducted. The outer lip of M. paranaguensis and environmental variables were measured.

Miranda f3

Miranda f2

One and two abundance peaks were observed for A. fulica and M. paranaguensis, respectively. Survivorship was higher in A. fulica. Distribution was aggregate for M. paranaguensis, whereas for A. fulica it varied from random to aggregate. Both species aggregate as abundance increases. The lifespan of M. paranaguensis in this location is shorter than its lifespan in a nearby location. Achatina fulica was affected by soil temperature and humidity; M. paranaguensis was influenced by humidity. Niche overlap was random. The results show that M. paranaguensis can keep its
natural activity and abundance in the presence of A. fulica, but environmental degradation impacts M. paranaguensis and should be evaluated.”

As can be seen from the above figures, the observations were made during one year resp. 7 months. The conclusions thus have to be viewed within the context of this limited evidence.

References:
Miranda, M.S., Fontenelle, J.H. & Pecora, I.L. (2014 [2015]). Population structure of a native and an alien species of snail in an urban area of the Atlantic Rainforest. – Journal of Natural History, 49: 19-35.