Strategies for Controlling the Apple Snail Pomacea canaliculata (Lamarck) (Gastropoda: Ampullariidae) in Japanese Direct-Sown Paddy Fields

Abstract

The apple snail Pomacea canaliculata becomes a much more serious pest in direct-sown rice fields than in transplanted fields. In south Japan, it represents an important constraint on the implementation of direct seeding. Described here are possible measures to control the snails and suggestions for its management in Japanese direct-sown rice fields. Crop rotation with upland crops is a practical way with the lowest extra cost. The apple snails were often not eradicated by growing an upland crop in the previous summer. However, snail densities always decreased below the control threshold in directsown fields (0.5 snails/m 2 ). Longer drainage period after sowing greatly reduced snail damage. Thus, draining fields for 10 to 20 days after sowing is a basic practice to control snails in direct seeding. Tillage and puddling have a function to crush snails and, thus, reduce snail densities. "Intensive tillage", in which a field with compacted hard soil is tilled shallow with faster cultivator rotation, achieved higher snail mortality. It is recommended to lower the risk of snail damage after unexpected heavy rain. An application of bait type metaldehyde showed enough control effects to avoid rice damage by snails even in heavy rain conditions. The stable effects seemed to be due to the active ingredient in the bait type which is dissolved slowly. Improving techniques for weeding and for draining fields effectively are necessary for better snail management in direct seeding.

Life cycle of the apple snail Pomacea canaliculata (Caenogastropoda: Ampullariidae) inhabiting Japanese paddy fields

“…On the other hand, few studies have examined its basic ecology, including life cycle and population dynamics under natural conditions (Ozawa and Makino, 1989;Shobu, 1996;Wada, 2000;Martin and Estebenet, 2002). In particular, none have monitored the snail populations over a long period (Ͼ1 year) on a regular basis (at least once a month), which impedes the elucidation of detailed life cycle patterns and population dynamics in this highly flexible (Estebenet and Cazzaniga, 1992;Martin and Estebenet, 2002) as well as fast-growing (Tanaka et al, 1999) snail.…”

“…This snail invaded many Asian countries, mainly in the 1980s (Halwart, 1994). It voraciously attacks rice seedlings, and various control methods, including chemical, biological and cultural, have therefore been studied (Shobu, 1996;Wada, 2000;Takahashi et al, 2002;Wada et al, 2004).…”

“…Most population studies have so far been conducted either in the original locality (Argentina: Martin and Estebenet, 2002) or in relatively warm districts in Japan (Shizuoka, Pacific coast of Honshu Island: Ozawa and Makino, 1989;Kyushu Island: Shobu, 1996;Wada, 2000). Information concerning P. canaliculata in cold districts is very scarce (Suzuki and Fukuda, 1988;Ito, 2002); thus, it is unknown whether the snail leads similar life cycles in paddy fields in cold districts.…”

Physiological response to low temperature in the freshwater apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae)

“…It was introduced into Asia, including Japan, as a human food mainly in the early 1980s. However, it has become a serious pest of rice in invaded countries (Wada, 2004;Cowie et al, 2006;Hayes et al, 2008). In temperate Japan the snails hibernate in paddy fields, irrigation canals, ponds and other bodies of water.…”

Global status of fish-borne zoonotic trematodiasis in humans

“…Snails can be controlled indirectly by reducing the suitability of their habitat or directly by removing them through chemical, physical, or biological control (Hoffman 1970;Sturrock 1995;Terhune et al 2003). For chemical control, molluscicides such as niclosamide, copper compounds, hydrated lime, sodium chloride and calcium cyanamide could be used in ponds (Hoffman 1970;Rondelaud and Dreyfuss 1996;Sturrock 1995;Khallaayoune et al 1998;Terhune et al 2003;Wada 2004;Mostafa et al 2005;Campbell et al 2002;Wui and Engle 2007). Most molluscicides, however, are toxic to fish as well and therefore their use in aquaculture ponds may be limited to ponds with out fish.…”