Predator, prey and pathogen interactions in introduced snail populations

Abstract

The introduction of the carnivorous snail Euglandina rosea to Pacific islands by biological control programmes has had a devastating effect on native snail populations. In most areas the target species, Achatina fulica, has not been affected, although some unsubstantiated reports have led to E. rosea being viewed as an effective control agent. Data from recent laboratory and field studies of E. rosea were combined into a simple model of the interactions between populations of E. rosea and A. fulica and a disease agent. Predictions from the model correspond closely with field data from a number of sites. The model suggests that apparent reductions in A. fulica numbers following E. rosea introduction are the result of a combination of predation and disease effects, and that although the maximum population levels are reduced the population is stabilized at a relatively high level. The model predicts that both A. fulica and E. rosea populations will persist. Partulidae will decline following E. rosea invasion although Samoana spp. may persist at reduced densities. More effective control of A. fulica can be achieved through manual collecting. Control of E. rosea requires the imposition of a significant novel mortality factor.

Distribution, movement, and microhabitat use of the introduced predatory snailEuglandina roseain Hawaii: implications for management

“…This study demonstrated that E. rosea , other non‐native prey species, and native snails (‘tornatellinids’) are found in much higher densities in the gulch than on the ridges. Populations of fast‐reproducing species are the least affected by E. rosea (Gerlach ). The high numbers of native ‘tornatellinids’ in the gulch indicate that these snails are able to persist in areas where E. rosea is present.…”

“…It was introduced to many Pacific islands to control populations of another introduced snail, Achatina fulica Bowdich 1822, the giant African snail (Davis & Butler ). However, the introduction of E. rosea has not reduced population sizes of A. fulica (Civeyrel & Simberloff ; Cowie ; Gerlach ), but instead has been associated with the decline of many species of native land snail, particularly tree snails (see references above).…”

Microbial ecology of biological invasions

“…However, these visible biota can have major impacts on the more invisible, microbial components of ecosystems and on the processes that microbes drive. Moreover, there is increasing awareness of invasive microbes, including human, animal or plant diseases, which can in some cases change the appearance and functioning of entire ecosystems (Liebhold et al, 1995;Gerlach, 2001;Jules et al, 2002;Niwa et al, 2004;Waring and O'Hara, 2005).…”

Mucus trail tracking in a predatory snail: olfactory processing retooled to serve a novel sensory modality

“…While there has been a report of trail following by Cantareus snails, trail following is not a prominent part of their behavioral repertoire. This is in sharp contrast to Euglandina, who follow nearly all trails encountered regardless of their state of hunger or satiety, and even if characteristics of the snail that they are following make it unsuitable for consumption (Cook 1985b(Cook , 1989Kinzie 1992;Gerlach 2001;Clifford et al 2003;Davis-Berg 2011).…”

“…In the field, Euglandina are voracious predators that, except for a specific, possibly distasteful slug, are known to eat almost any molluscan prey they encounter (Cook 1985b, 1989; Kinzie 1992; Gerlach 1999, 2001; Meyer and Cowie 2010; Davis-Berg 2011). In the laboratory, Euglandina easily distinguish mucus of prey snails from that of other Euglandina .…”