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Gonaxis kibweziensis

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Gonaxis kibweziensis

Summary

  • Last modified
  • 16 November 2018
  • Datasheet Type(s)
  • Documented Species
  • Preferred Scientific Name
  • Gonaxis kibweziensis
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Mollusca
  •       Class: Gastropoda
  •         Subclass: Pulmonata
  • Summary of Invasiveness
  • G. kibweziensis is a non-specific predatory snail, taking a number of other snail species as prey. The species is not widely recognized as invasive. While it has become widely distributed in the islands of the...

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Identity

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Preferred Scientific Name

  • Gonaxis kibweziensis E.A. Smith

Other Scientific Names

  • Eustreptaxis kibweziensis E.A. Smith
  • Gonaxis (Macrogonaxis) kibweziensis E.A. Smith
  • Macrogonaxis kibweziensis E.A. Smith
  • Streptaxis kibweziensis E.A. Smith

International Common Names

  • English: kibwezi gonaxis

Local Common Names

  • Guam: akaleha'; carnivore snail

Summary of Invasiveness

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G. kibweziensis is a non-specific predatory snail, taking a number of other snail species as prey. The species is not widely recognized as invasive. While it has become widely distributed in the islands of the Pacific and Indian Oceans as a biological control agent against giant African snails, continues to be spread in at least some regions by human agencies, and is known to interact with some native mollusc species, G. kibweziensis has not been unequivocally confirmed as threatening ecosystems, habitats or species or having major economic consequence.

Predation on native snails in regions to which G. kibweziensis has been introduced is undoubtedly occurring. Concern about G. kibweziensis effects on native land snail communities has been expressed in a number of countries to which the species has been introduced as a biological control agent, but definitive evidence for such effects is presently lacking. The use of generalized predators in biological control programs has long been recognized as unsafe due to expected environmental impacts, not least adverse effects on non-target species.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Mollusca
  •             Class: Gastropoda
  •                 Subclass: Pulmonata
  •                     Order: Stylommatophora
  •                         Suborder: Sigmurethra
  •                             Unknown: Streptaxoidea
  •                                 Family: Streptaxidae
  •                                     Genus: Gonaxis
  •                                         Species: Gonaxis kibweziensis

Notes on Taxonomy and Nomenclature

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Gonaxis kibweziensis was originally described by Smith (1894: 165, fig. 1) as Streptaxis kibweziensis, with Kibwezi, Kenya as the type locality. Subseqently it was assigned to genus Gonaxis.

The taxonomic placement of G. kibweziensis within the Streptaxidae continues to be unstable. The species has been referred to Macrogonaxis Thiele 1932 (type species Streptaxis enneoidesMartens, 1878), usually as a subgenus of Gonaxis but also often treated as a genus distinct from Gonaxis. However, G. kibweziensis differs anatomically, and recent molecular and morphological phylogenetic analyses (Rowson, 2009) suggest that G. kibweziensis has stronger affinities with Tayloria Bourguignat, 1889 (type species Tayloria joubertiBourguignat, 1889) than Gonaxis Taylor, 1877 sensu stricto. The correct subfamily assigned is thus considered Odontartemoninae by Rowson (2009).

G. kibweziensis has been assigned to genus Eustreptaxis Pfeiffer, 1878 (type species Helix contusaFérussac, 1820) by Abbott (1989), Ranawana (2006), Naggs and Raheem (2005), and others. However, Eustreptaxis is an objective junior synonym of the South American Streptaxis J. Gray, 1837 (type species Helix contusaFérussac, 1820) in Streptaxinae.

G. kibweziensis is conchologically similar to Gonaxis enneoides – with which it overlaps geographically in Kenya and Tanzania, such that specific epithets have occasionally been wrongly applied – see discussion by Adam (1965). Gerlach and Bruggen (1999) suggested that the specific level distinctiveness of G. kibweziensis from G. quadrilateralis [a species also widely used in biological control programmes] and some other East African snails currently assigned to Gonaxis requires reevaluation.

No common name is in wide usage.

Description

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The shell of G. kibweziensis is translucent white, and dorso-ventrally distorted due to allometric changes during shell ontogeny. The juvenile shell is discoidal dome-shaped; the adult shell more globose and with the axis of coiling at about 13° angle to the axis of the juvenile. When the adult shell is examined in apertural view, the juvenile whorls sit atop and displaced to one side by the broader last two whorls of the adult whorls. Adult whorls with broadly rounded periphery. Aperture rounded, without barriers, with somewhat thickened and slightly reflected margins; parietal callus well developed. Umbilicus a minute perforation.The protoconch is smooth. The teleconch whorls are delicately ribbed.

Shell height 15 to 22 mm, diameter about 95% of shell height. Spire about 17% and aperture about 57% of overall shell height.

Animal yellowish-orange, with darker orange optic peduncles.

Simultaneous hermaphrodite. Oviparous, producing small clutches of eggs with calcified shells. Ovotestis embedded in digestive gland at shell apex. Pallial female and male gonoducts united as spermoviduct. Bursa copulatrix a small sac adjacent to albumen gland, on a long duct than increases in diameter towards junction with the free oviduct. Vagina large, muscular. Vas deferens long, convoluted. Penis rather elongate, lacking a sheath, and equipped internally with conchiolinous hooks, each born on a low rhombic pad. Penial retractor muscle arising from columellar muscle and inserting on penial apex, adjacent to the point of insertion of the vas deferens.

Predatory. Buccal mass muscular, elongate, occupying nearly the whole of the head/neck region. The buccal mass and cartilaginous odontophore are evertible through the mouth by hydrostatic pressure during feeding, such that the radula teeth splay out at the anterior end to grasp the prey. The prey is either swallowed whole or in pieces. Radular teeth elongate, unicuspid. Jaw absent. Intestinal tract short.

Distribution

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G. kibweziensis is native to Kenya and Tanzania in East Africa, but has been introduced to many Pacific and Indian Ocean Islands as a biocontrol agent of giant African snail, Achatina fulica.G. kibweziensis is not listed as threatened in any part of its native range, reflecting the continuing abundance of the species in both natural and modified habitats.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

Indonesia
-Irian JayaAbsent, formerly presentIntroduced1959Waterhouse and Norris, 1987; Barker and Efford, 2004Introduced from Papua New Guinea as biocontrol agent for giant African snail. Released, but evidently failed to establish
JapanPresentPresent based on regional distribution.
-Ryukyu ArchipelagoLocalisedIntroduced1958-61Waterhouse and Norris, 1987; Civeyrel and Simberloff, 1996; Barker and Efford, 2004Introduced via Hawaii as biocontrol agent for giant African snail. Established.
Sri LankaLocalisedIntroduced1950 Not invasive Barker and Efford, 2004; Naggs and Raheem, 2005; Ranawana, 2006Introduced as biocontrol agent for giant African snail. Established at Peradeniya.

Africa

ComorosIntroduced1970Ranaivosoa, 1971; Barker and Efford, 2004Introduced from Trinidad for biological control of giant African snail. Current status unknown.
KenyaLocalisedNativeBequaert and Clench, 1936; Verdcourt, 1983; Rowson, 2009Kibwezei, Voi, Taru Desert, Taita Mountains
MadagascarLocalisedIntroduced1962Jenkins, 1987; Fischer-Piette et al., 1994Introduced as biocontrol agent for giant African snails.
MayotteIntroduced1965Abdou et al., 2004; Soubeyran, 2008Introduced as biocontrol agent for giant African snail
SeychellesAbsent, unreliable recordIntroduced1958Greathead, 1971Introduced as biocontrol agent for giant African snail. Not listed by Gerlach and Bruggen (1999). Probably erranous record, referring to Gonaxis quadrilateralis.
TanzaniaLocalisedNativeBequaert and Clench, 1936; Verdcourt, 1983; Tattersfield et al., 1998; Rowson, 2009Ruvu; Kibosho

North America

BermudaIntroduced1958-60 Not invasive Simmonds and Hughes, 1963; Cowie, 2001; Barker and Efford, 2004Introduced as biocontrol agent for helicid snails
USAPresentPresent based on regional distribution.
-CaliforniaAbsent, formerly presentIntroduced1956-57 Not invasive Claussen, 1959; Hanna, 1966Introduced as biocontrol agent for helicid snails in San Diego County. No establishment.
-HawaiiLocalisedIntroduced1952-1955Fullaway, 1952; Cowie, 1997; Barker and Efford, 2004Introduced from Kenya, and subsequently from North Mariana Islands as biocontrol agent for giant African snail. Established on Oahu and Maui.

Oceania

American SamoaWidespreadIntroduced1977 Not invasive Miller, 1993; Cowie and Cook, 1998Introduced from Hawaii as biocontrol agent for giant African snail. Establised on Tutuila.
GuamLocalisedIntroduced1952-55 Not invasive Mead, 1979; Muniappan, 1983; Hopper and Smith, 1992Introduced as biocontrol agent for giant African snail
Micronesia, Federated states ofPresentIntroduced1955Mead, 1979; Smith, 1993Introduced to Ponape and Truk from Northern Marianas Islands as biocontrol agent for giant African snail.
New CaledoniaLocalisedIntroduced1979 Not invasive Tillier, 1992; Jourdan and Mille, 2006Introduced from Palau as biocontrol agent for giant African snail, but evidently did not establish.
Northern Mariana IslandsLocalisedIntroduced1950Owen, 1951; Anon, 1953; Abbott, 1989; Berger, 2005Introduced from Kenya to Agiguan as a biocontrol agent for giant African snail in Saipan, Tinian and Rota.
PalauLocalisedIntroduced>1950 Not invasive Rundell, 2005; Hadfield, 2010Introduced from Kenya, via Hawaii, as biocontrol agent for giant African snail. Present on Ngatpang, Ngerekebesang, and Pagan.
Papua New GuineaLocalisedIntroducedParkinson et al., 1987New Britain; Bougainville Is.

History of Introduction and Spread

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G. kibweziensis was introduced to many Pacific and Indian Ocean Islands as a biocontrol agent of giant African snail (Achatina fulica) - an invasive species with major impacts on native flora and fauna, on agriculture, and on human health. However, while G. kibweziensis predation on giant African snails has been amply demonstrated, its role in regulation of giant African snail populations has not. G. kibweziensis has also been introduced into Bermuda and California as a control agent for pest helicid snails, but again effectiveness has not been demonstrated. Thus the benefits of past introductions of G. kibweziensis have not been firmly established and justifications are lacking for further introductions as a biocontrol agent.

The first research on natural enemies of giant African snail was sponsored by the Pacific Science Board of the U.S. National Research Council and by the U.S. Office of Naval Research, with work in Africa by F.X. Williams in 1947-48. Following observations that indicated apparent importance as a natural control agent of Achatinidae in their native African habitat (see Willams, 1951, 1953), G. kibweziensis was introduced into the Pacific Islands for control of giant African snail by the Hawaiian Board of Agriculture and Forestry, with an initial field evaluation as a control agent of giant African snail occurring in the Northern Mariana group, commencing in 1950, undertaken by the Insect Control Committee for Micronesia (Mead, 1961). Even before the field evaluation had run in course in the Northern Mariana and before laboratory tests were completed in Hawaii, G. kibweziensis was released and perfunctorily evaluated in the field in the Hawaiian islands.

Despite very weak evidence of the effectiveness as a control agent of giant African snail in the Northern Mariana and Hawaiian Islands, and an emerging recognition of its potential impacts on native snail faunas due to its non-specific predatory activity (see summary in Cowie, 2001), interest in G. kibweziensis gained momentum as giant African snail gained prominence as a pest. Releases of G. kibweziensis subsequently occurred in several countries in the Indo-Pacific region in official biological control programmes. In addition to those in Northern Mariana and Hawaiian Islands, introductions of G. kibweziensis for biological control have been documented in New Caledonia, Irian Jaya, Papua New Guinea, Federated States of Micronesia, Guam, Palau, American Samoa, Okinawa (Japan), Sri Lanka, Comoras, Madagscar, Mayotte, Bermuda, and California (USA). Undoubtly other cases have yet to be documented.

Risk of Introduction

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While use of generalist predators in biological control is now widely discouraged, there remains much interest in predatory snails as control agents in countries afflicted by introductions of giant African snail and other achatinid species. The prospects for unofficial and illegal deliberate introductions of G. kibweziensis and other predatory snails thus remains high. No natural enemies are known to specialize on G. kibweziensis as prey or hosts.

Habitat List

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CategoryHabitatPresenceStatus
Terrestrial-managed
Disturbed areas Secondary/tolerated habitat Natural
Managed forests, plantations and orchards Secondary/tolerated habitat Natural
Terrestrial-natural/semi-natural
Natural forests Principal habitat Natural
Natural grasslands Secondary/tolerated habitat Natural
Scrub / shrublands Secondary/tolerated habitat Natural

Biology and Ecology

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Reproductive Biology

G. kibweziensis is a hermaphroditic, out-crossing species. The snails require about six months to reach reproductive maturity, which is attained prior to the shell reaching full size and thickening/reflection of the aperture margin. The species is oviparous, laying clutches of 3-4 eggs in the soil. Upon oviposition, the eggs are generally encased in an earthern accretion (‘pod’ according to some authors).

G. kibweziensis has low reproductive potential – each individual giving rise to a maximum of 11 offspring per year in the laboratory (Kondo, 1956). Nonetheless, it has proved to have high productivity in the field. For example, Kondo (1952) estimated that 400 snails released on Agiguan in the Northern Mariana Islands in 1950 had increased to an estimated 21,750 within two years.

Nutrition

G. kibweziensis is predatory, feeding on snails and snail eggs. The species has strong cannibalistic tendencies. Foraging activity is usually at night or during rainy days.

Environmental Requirements

G. kibweziensis is mainly found in partially shaded areas, both in forests and other wooded habitat. It is entirely ground dwelling, and will burrow into the soil to aestivate during dry periods.

Climate

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ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Tolerated Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
B - Dry (arid and semi-arid) Tolerated < 860mm precipitation annually

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Endeavouria septemlineata Predator Adults/Juveniles not specific
Platydemus manokwari Predator Adult Male/Juvenile not specific N
Rattus Predator All Stages not specific N
Tefflus zanzibaricus alluaudi Predator Adults/Juveniles not specific

Notes on Natural Enemies

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There have been very limited studies of G.kibweziensis ecology. Records of natural enemies have arisen largely from incidental, opportunistic observations, primarily associated with use in biological control programmes. No natural enemies are known to specialize on G. kibweziensis as prey or hosts.

Means of Movement and Dispersal

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G. kibweziensis has been deliberately introduced to several countries as a biological control agent for pest snails, notably giant African snail Achatina fulica. While G. kibweziensis has not been effective as a control agent, and is recognized as a potential threat to native snails, there is continuing interest in its potential in biological control, especially in regions in which giant African snail has recently established. While use of generalist predators in biological control is now widely discouraged, the prospects for unofficial deliberate introductions of G. kibweziensis and other predatory snails remains high.

There are no documented cases of accidental introductions of G. kibweziensis associated with trade and transport. The risk of accidental dispersal and introduction are presently regarded as low due to the localized distribution in both the native and introduced ranges, and the species’ strictly ground-dwelling behaviour reducing likelihood of accidental infestation of produce and freight. Nonetheless, the potential for accidental introductions from regions where G. kibweziensis has established is likely to increase as the species continues to spread from release sites and become more prevalent in agricultural and urban areas.

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Biological controlControl agent for giant African snail Yes Yes Barker and Efford, 2004; Civeyrel and Simberloff, 1996

Impact Summary

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CategoryImpact
Environment (generally) Negative

Impact: Environmental

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G. kibweziensis is a non-specific predator, taking a number of snail species as prey. G. kibweziensis was identified as a predator of achatinid snails in its native East Africa during a study to identify potential biological control agents of the invasive giant African snail. G. kibweziensis was subsequently introduced to Hawaii and the Northern Mariana Islands, and thence to other regions in the Indo-Pacific, for this purpose.

Contrary to early ascertions (Anon, 1956a, b), there has been no evidence that G. kibweziensis effects any real control of achatinid snails in East Africa (Abbott, 1951; Mead 1961). What is more, there has been limited investigation of the effectiveness of G. kibweziensis in controlling giant African snail where the predator was introduced as a biocontrol agent.

In an initial study, between 1952 and 1955, the effectiveness of G. kibweziensis was evaluated in the Northern Mariana Islands, from which Kondo (1956) stated “In 1952 this snail was estimated to exercise 20 percent control over Achatina fulica in the <35 mm size class [also see Kondo, 1952]. The 1954 figure for control was estimated at 60 per cent.” Subsequent similar evaluations of G. kibweziensis in Hawaii (Davis and Butler, 1964; Nishida and Napompeth, 1975) also purported to show the species’ effectiveness in controlling giant African snail. However, as summarized by Cowie (2001), these evaluations in Northern Mariana and Hawaiian Islands were grossly inadequate in lacking appropriate control areas where no predatory snails have been introduced, and lacking sampling designs that accommodated seasonal fluctuations in numbers and which could differentiate among mortality factors.

Christensen (1984), Civeyrel and Simberloff (1996) and Cowie (2001) could find no evidence for success of G. kibweziensis as an introduced biocontrol agent targeting giant African snail.

The introductions of G. kibweziensis into Northern Mariana and Hawaiian Islands, and beyond, in biological control programmes evidently had little regard for potential non-target impacts. This is despite the recognition of G. kibweziensis as a non-specific predator and words of caution. Williams (1951) for example stated “If these predators were successfully established on some of the Pacific Islands where the giant African snail (Achatina fulica) is present, undoubtedly they would reduce the Achatina population considerably. However, the native terrestrial, but probably not the whole arboreal, land snail fauna undoubtedly also would be reduced, perhaps not exterminated.” Kondo (1950, 1951) had already found in laboratory trials in Hawaii that G. kibweziensis exhibited a definite preference for several species of terrestrial and arboreal snails endemic to Oahu.

As would have been predicted, observations in the Northern Mariana and Hawaiian Islands subsequently confirmed that G. kibweziensis preys on snail species in addition to its intended target the giant African snail. For example, Kondo (1952) observed predation on the native Omphalotropids erosa on Agiguan, and Davis and Butler (1964) observed predation on the introduced species Subulina octona, Bradybaena similaris and Euglandina rosea, and several “species of native snails” in Hawaii. Nonetheless, the impact of G. kibweziensis on native snails within the introduced range has yet be studied in any detail. As indicated by Cowie (1998), Cowie and Cook (1998), Sherley (2000), Berger (2005) and others, G. kibweziensis poses a potential, although poorly understood threat to indigenous land snails. It is present on Tutuila (the largest island of American Samoa) where threatened native snails include Ostodes strigatus, but the population of G. kibweziensis may be in decline here (US Department of Interior, 2014a).

Kondo (1950) was unable to demonstrate in the laboratory any tendency for Gonaxis to consume earthworms.

Risk and Impact Factors

Top of page Invasiveness
  • Abundant in its native range
  • Is a habitat generalist
  • Tolerant of shade
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
Impact outcomes
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Predation
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Highly likely to be transported internationally illegally
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses

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G. kibweziensis has been utilized as a biological control agent for pest snails, in particular giant African snail Achatina fulica. However, there is limited evidence for its effectiveness in biological control (see Environmental Impact section for details).

Uses List

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Environmental

  • Biological control

Similarities to Other Species/Conditions

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Numerous species in Africa are similar in possessing streptaxomorph shells - defined as those in which the adult coiling axis deviates to the right, when the shell is oriented in apertural view. G. kibweziensis is conchologically similar to Gonaxis enneoides and G. quadrilateralis with which it overlaps geographically in Kenya and Tanzania.

Prevention and Control

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Prevention

SPS Measures

Under statutory authorities provided by Chapter 183D, Hawaii Revised Statutes, the Department of Land and Natural Resources maintains Hawaii Administrative Rules Chapter 124, which defines “injurious wildlife” as “any species or subspecies of animal except game birds and game mammals which is known to be harmful to agriculture, aquaculture, indigenous wildlife or plants, or constitute a nuisance or health hazard and is listed in the exhibit entitled “Exhibit 5, Chapter 13-124, List of Species of Injurious Wildlife in Hawaii…” That list includes G. kibweziensis.

Rapid Response and Public Awareness

As with other terrestrial gastropod species, once established in an area, eradication is most unlikely. The most effective management option includes a combination of prevention of dispersal, early detection and rapid response, and control. To prevent species such as G. kibweziensis from spreading, public education can raise awareness to reduce human mediated spread, coupled with robust border inspection and quarantine procedures. Early detection and rapid response would strategically involve surveillance by biologists, and a form to enable the public to report sightings. Control options in the event of incursion are extremely limited, and would largely rely on physically removing and destroying snails and their eggs. Chemical treatments via application of baits containing a molluscicide - the control method of choice in controlling herbivorous slugs and snails - is likely to be ineffective in combating predatory snails such as G. kibweziensis.

Eradication

Eradication of terrestrial gastropods is generally not attempted, mainly because it is very difficult to achieve 100% mortality from chemical-based control options due to differential exposure and susceptibility of individuals, population resurgence from survivors, and hatch from eggs.

Experience with other gastropod pest species clearly demonstrates that it is feasible to eradicate incipient infestations, but to date there have been no successful attempts to eradicate long-established populations of invasive gastropod species on larger scales.

Control

Physical/Mechanical Control

Hand collection with subsequent destruction of animals is the oldest method of control of terrestrial pest gastropods (Godan, 1983), and has been used effectively in conjunction with chemical methods for management of infestations in agricultural areas and in eradication of incipient infestations of invasive herbivorous species.

However, manual removal as a control method has three primary constraints: the difficulty of finding sufficient numbers of individuals to effectively manage or eradicate the population; the high labour costs; and the physical disturbance to the habitat. These constraints are highest where the species/life stages being controlled are small and therefore difficult to detect in infested habitat. Adults of G. kibweziensis are large and thus potentially amenable to manual collection and destruction. However, the eggs and juveniles are much smaller and often concealed in the soil and under and within plant debris, reducing the prospects for control by manual removal.

Biological Control

Most natural enemies of terrestrial gastropods have proved not to be host-specific and therefore are not amenable for use in control programmes where effects on non-target species are of concern. To date, no natural enemy specific to G. kibweziensis is known.

Chemical Control

It is generally thought that predaceous snails are not amendable to chemical control. However, this has not been fully evaluated. Mead (1961) reported mortality in G. kibweziensis when introduced to a site in Oahu, Hawaiian Islands that had been treated with cement-lime-calcium arsenate bait [for giant African snail control]. The effectiveness of modern molluscicide chemicals and formulations (e.g. baits) against G. kibweziensis is not known.

References

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Abbott RT, 1951. Report on the introduction of natural enemies of the giant African snail to Agiguan Island, Maianas Islands. Invertebrate Consultants Commission for Micronesia, Pacific Science Board, National Research Council, 11 pp.

Abbott RT, 1989. Compendium of landshells., USA: American Malacologists, 240 pp.

Abdou A; Muratov I; Bouchet P, 2004. Mollusques terrestres de Mayotte: Éléments pour l'inventaire des ZNIEFF ([English title not available]). MNHN, 45 pp.

Adam W, 1965. [English title not available]. (Mission zoologique de l'I. en Afrique orientale (P. Basilewsky & N Leleup, 1957). LXXXV. Mollusca Streptaxidae.) Anales dun Musée Royal de l'Afrique Centrale (8),Sciences Zoologiques, 138:1-52.

Anon, 1953. Achatina fulica control experiments in the southern Marianas. Pacific Science Association Information Bulletin, 53(3-4):9-10.

Anon, 1956. Cannibal snail gets a job. Life, 40(16):159-160.

Anon, 1956. The hunter snail. Time, 67(2):44,46.

Barker GM; Efford MG, 2004. Predatory gastropods as natural enemies of terrestrial gastropods and other invertebrates. In: Natural enemies of terrestrial molluscs [ed. by Barker GM]. Wallingford, UK: CABI Publishing, 279-403. http://www.cabi.org/CABeBooks/default.aspx?site=107&page=45&LoadModule=PDFHier&BookID=209

Bauman S, 1996. Diversity and decline of land snails on Rota, Mariana Islands. American Malacological Bulletin, 12(1/2):13-27.

Bequaert J; Clench WJ, 1936. Studies of African land and fresh-water mollusks. Journal of Conchology, 20(9):263-273.

Berger GM, 2005. Comprehensive Wildlife Conservation Strategy for the Commonwealth of the Northern Mariana Islands. Report to U.S Fish and Wildlife Service., Commonwealth of the Northern Mariana Islands: Department of Lands and Natural Resources, Division of Fish and Wildlife.

Christensen C, 1984. Are Euglandina and Gonaxis effective agents for biological control of the giant African snail in Hawaii? American Malacological Bulletin, 2:98-99.

Civeyrel L; Simberloff D, 1996. A tale of two snails: is the cure worse than the disease?. Biodiversity and Conservation, 5(10):1231-1252.

Claussen CP, 1959. Releases of recently imported insect parasites and predators in California, 1956-57. Pan-Pacific Entomologist, 35(2):108.

Cowie RH, 1997. Catalog and bibliography of the nonindigenous nonmarine snails and slugs of the Hawaiian Islands. Bishop Museum Occasional Papers, No. 50. 1-66.

Cowie RH, 1998. Patterns of introduction of non-indigenous non-marine snails and slugs in the Hawaiian Islands. Biodiversity and Conservation, 7(3):349-368.

Cowie RH, 1998. Patterns of introduction of non-indigenous non-marine snails and slugs in the Hawaiian Islands. Biodiversity and Conservation, 7(3):349-368.

Cowie RH, 2001. Can snails ever be effective and safe biocontrol agents? International Journal of Pest Management, 47(1):23-40.

Cowie RH; Cook RP, 1998. Partulid and other land snails of the National Park of American Samoa. Tentacle, 8:14-15.

Davis CJ, 1954. Ecological studies, Island of Agiguan, Marianas Islands as related to the African Snail, Achatina fulica Bowdich, and its introduced predator, Gonaxis kibweziensis (E. Smith). Pacific Science Board, National Academy of Sciences National Research Council, 24 pp.

Davis CJ, 1961. Recent introductions for biological control in Hawaii-VI. Proceedings of the Hawaiian Entomological Society, 27(3):389-393.

Davis CJ; Butler jr GD, 1964. Introduced enemies of the giant African snail, Achatina fúlica Bowditch, in Hawaii (Pulmonata: Achatinidae). Proceedings of the Hawaiian Entomological Society, 18(3):377-389 pp.

Fischer-Piette E; Blanc CP; Blanc F; Salvat F, 1994. [English title not available]. (Gastéropodes terrestres pulmonés (excl. Veronicellidae et. Elisolimax).) Faune de Madagascar, 83.

Fullaway DT, 1952. Biological control of insect pests in the Hawaiian Islands since 1925. In: Rep. Bd. Agric. For. Hawaii 1950/1951-1951/1952. 98-105.

Gerlach J; Bruggen ACvan, 1999. Streptaxidae (Mollusca: Gastropoda: Pulmonata) of the Seychelles Islands, western Indian Ocean. Zoologische Verhandelingen Leiden, 328:1-60.

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Links to Websites

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GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gatewayhttps://doi.org/10.5061/dryad.m93f6Data source for updated system data added to species habitat list.

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03/06/16 Original text by:

Dr Gary Barker, Landcare Research, Hamilton, New Zealand

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