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Related invasive species

  • Cornu aspersum
Biological Control
<br>As terrestrial molluscs have many natural enemies, there has been strong interest in the biological control of C. aspersum using other, predatory snails (e.g. Fisher and Orth, 1985). However, as most of these predatory snails are not host-specific, they are not appropriate to use in control programmes in which effects on non-target species are of concern (Cowie, 2001: Barker and Watts, 2002).<br>There have been several attempts to develop biological control of C. aspersum in California, South Africa and New Zealand, which began with the introduction of predaceous snails (Euglandina rosea, Gonaxis sp.) and beetles during the 1950s and early 1960s (for more information see Fisher and Orth, 1985;Barker and Efford, 2004). These efforts were largely unsuccessful, although one staphylinid beetle (Staphylinus (Ocypus) olens) showed potential;however, the use of this species as a biological control in orchards has not been actively pursued (Sakovich, 2002). In 1966, however, another (opportunistic) predaceous snail, the decollate snail Rumina decollata (of European origin) was found to have invaded California (see Pictures). Experimental releases of R. decollata in southern California citrus orchards were begun in 1975 and, in most cases, resulted in complete control (displacement) of C. aspersum (Fisher and Orth, 1985). Rumina decollata is now used to control C. aspersum in some 20,000 ha of citrus in southern California, but is currently permitted only in certain Californian counties (Dreistadt et al., 2004). As this predatory snail consumes young to half-grown snails, control is achieved only in 4-6 years. Sakovich (2002) recommended first using molluscicidal baits to reduce the population, and then combining skirt-pruning and copper barriers with introduction of R. decollata. Once control by R. decollata is achieved, maintenance of copper barriers can cease, R. decollata can be harvested and transferred to new areas. However, Cowie (2001) expressed concern regarding both the effectiveness of R. decollata in control of C. aspersum, its potential impacts on native (even endangered) species and its potential as a garden plant pest.<br>A study by Altieri et al. (1982) was carried out in a daisy field in northern California to determine the effectiveness of the indigenous coleopterous predator Scaphinotus striatopunctatus in the biological control of C. aspersum. Release of the predator in the field under light metal sheets, together with colonization by garter snakes (Thamnophis elegans) from an adjacent field, resulted in a significant reduction in snail populations.<br>In South Africa, the native predacious gastropod Natalina cafra was investigated as a potential biological control agent against C. aspersum, with special attention to the possibility of establishing a viable population of the natural enemy in captivity (Joubert, 1993), but this approach seems not to have been implemented.<br>Research by the Entomology Division of the Plant Protection Department, Cukurova University, Turkey, on the importation of predators and parasitoids as biological control agents (mainly for citrus pests) included the coccinellid Hippodamia convergens as a potential predator of C. aspersum (Uygun and Sekeroglu, 1987).<br>Ducks, chickens or guinea fowl can provide long-term control in citrus orchards and vineyards, if an appropriate breed is chosen and properly cared for. Growers take the animals each morning into the orchard for as little as half an hour to scavenge for food. This solution can be very effective but involves extra labour in managing the animals and protecting them from predators (Sakovich, 2002;Davis et al., 2004).
Has Cabi datasheet ID
26821
Detection


The following information is from the Canadian Food Inspection Agency Cornu aspersum fact sheet (CFIA, 2014).
Indications of an attack by C. aspersum are ragged holes chewed in leaves, with large veins usually remaining;holes in fruit;and slime trails and excrement on plant material.
Adults and larger juveniles are likely to be visible among the host material or attached to the transporting containers. They may also be hidden in protected locations, sealed into their shells to avoid desiccation. Check the undersides of containers and their rims. Small snails and eggs in soil could be difficult to find. C. aspersum hides in crevices and will overwinter in stony ground.
Inspections are best carried out under wet, warm and dark conditions. Under bright, dry conditions it is necessary to thoroughly search dark, sheltered areas where the humidity is elevated, such as under low-growing plants or debris. The snails may bury themselves in loose soil or other matter, so the only way to be reasonably sure an area is not infested is to make repeated surveys over a long period of time.

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