Beware of golden kuhol (Pomacea canaliculata) after planting rice as this voracious pest can devour a whole paddy overnight. According to Tony Martin of the PhilRice Crop Protection Division, yield loss owing to golden kuhol can be massive but variable. In the Philippines, losses range from 5% to 100% depending on locality and the level of infestation. Yield loss is also related to the density and size of the snails. A single snail can eat 7 to 24 rice seedlings a day.
The golden kuhol, which came from South America, was introduced in Taiwan as food. It became an aquarium pet and was used to clean fish tanks as it feeds on aquarium scum. The snails multiplied rapidly and began to escape in waterways. The golden kuhol later spread to Indonesia, Thailand Cambodia, Hong Kong, southern China, Japan, and the Philippines.
The golden kuhol was introduced in the Philippines between 1982 and 1984. Its high nutritive value as food for humans and farm animals generated interest among both public and private sectors. A few years after its introduction, however, it became a major pest of rice. In a book chapter written by Matthias Halwart in the "Global Advances in the Ecology and Management of Golden Apple Snails", he said the golden kuhol directly affects the livelihood of Asian farmers by infesting and damaging over half of the rice fields in the Asian region. According to Halwart, the golden kuhol is most destructive when the length of the shell is from 10mm (size of a corn seed) to 40mm (size of a pingpong ball). This is the stage when they need the large amounts of food for their growth and survival. Dr. Ravindra Joshi, PhilRice crop protection expert, said rice fields are an ideal habitat for golden kuhol as these depend mainly on the rice plants as food source.
The golden kuhol feeds on young succulent plants such as newly transplanted rice seedlings and emerging tillers as well as weeds during the night and at dawn, he added. Martin said farmers should integrate various management options for golden kuhol.
The following are some of the recommendations:
- Before the final harrowing, destroy egg clusters and handpick golden kuhol from rice paddies in the morning and afternoon when they are most active and easy to find.
- Use plants containing toxic substances against golden kuhol such as gugo, tubing-kamisa, sambong, tuba-tuba, gabi-gabihan, tobacco, tubli, makabuhay, calamansi and red pepper is also effective in golden kuhol control.
- Put a wire or woven bamboo screen at the main irrigation water inlet and outlet to prevent the entry of hatchlings and adults and to facilitate the collection of golden kuhol.
- Molluscicides can kill non-target organisms and other beneficial organisms. Improper use of molluscicides can cause skin irritation and can damage nails, thus, it must be handled properly.
To know more about the golden kuhol, read “Global Advances in the Ecology and Management of Golden Apple Snails”, edited by Dr. Ravindra Joshi and Dr. Leocadio Sebastian, PhilRice Executive Director. The book tells about the ecology and management of golden kuhol, snail taxonomy (traditional and molecular tools), impacts on aquatic ecosystems and farmers' health, and pesticide abuse/misuse. Other topics such as the utilization of golden kuhol as a biological weeder and as means of food recipe are also included.
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