Common name

Golden apple snails

Scientific name

There are more than 100 species of apple snail that exist.

Two species, Pomacea canaliculata and Pomacea maculata, are highly invasive and cause damage to rice crops.

 

What it does

Golden apple snails eat young and emerging rice plants. They cut the rice stem at the base, destroying the whole plant.

Why and where it occurs

Snails are able to spread through irrigation canals, natural water distribution pathways, and during flooding events.

When water is absent, apple snails are able to bury themselves in the mud and hibernate for up to 6 months . When water is re-applied to fields, snails may emerge.

Higher sowing density in planting can attract more snails. They damage direct wet-seeded rice and transplanted rice up to 30 days old. Once the rice plant reaches 30 days, it is thick enough to resist the snail.

 

How to identify

To distinguish golden apple snails from native snails, check its color and size.

Golden apple snails have muddy brown shell and golden pinkish or orange-yellow flesh. They are bigger and lighter in color compared to native snails. Its eggs are bright pink in color.

To confirm snail damage, check for missing hills, cut leaves, and cut stems.

How to manage

The critical time to manage golden apple snails is during land preparation and crop establishment or planting; specifically, first 10 days after transplanting, and first 21 days after direct wet-seeding.

After this, the crop is generally resistant to snail damage and snails are actually beneficial by feeding on weeds.

Community-based snail management

To best control the snail, communities should work together to reduce snail numbers in their area.

• Conduct mass snail and egg collection campaigns, involving the whole community, during land preparation and planting or crop establishment.
• Keep fields drained as much as possible during the vulnerable stages of the rice plant (below 30 days) or transplant 25−30 day old seedlings from low density nursery beds.

Biological control

• Encourage natural predators.
• Red ants feed on snail eggs.
• Ducks (and sometimes rats) eat young snails.
• Several wild bird species also feed on golden apple snails.
• Snails can also be harvested, cooke, and eaten or sold as animal feed.

Cultural control

• Handpick snails and crush egg masses.
• Keep water level below 2 cm during vulnerable stages of the rice plant.
• Use toxic plants such as tobacco leaves, heartleaf false pickerelweed, and citrus leaves in strips across the  field or in canalettes.
• Where water enters and leaves the field, place a barrier.
• When possible, transplant rice in the field. Transplanted rice is less vulnerable than direct seeded rice.

Chemical control

• Apply products only to low spots and canalettes rather than to the whole field. Always ensure safe application.
• If used, molluscicides should only be used immediately after transplanting or during the seedling establishment phase in direct seeded rice; and only for rice older than 30 days old.

 

Learn more

View full fact sheet:
Golden apple snail on IRRI Rice Knowledge Bank