Molluscicidal action of some Philippine plants on golden snails, Pomacea spp.

A total of 138 extracts (119 water, 8 methanol, 3 chloroform, 8 volatile oils) from 91 plants were evaluated for mulluscicidal activity against golden snails, Pomacea spp. (P. canaliculata, P. gigas and P. cuprina). Based on the concentrations that caused 80-100 percent mortality at 48 hours after treatment (HAT), 16 extracts exhibited very high toxicity (200 ppm and below), 16 had high toxicity (200-1,000 ppm), 8 had moderate toxicity (1,000-5,000 ppm). 40 had low toxicity (5,000-10,000 ppm) and 58 were inactive (10,000 ppm). In most cases, the oils were more highly toxic (VHT) at 200 ppm and below than the organic extracts which in turn were more active than the water extracts. Based on the LC100, the order of decreasing toxicity of the volatile oil is: Curcuma longa Blumea balsamifera C. zedoaria = Ocimum sanctum Cinnamomum mercadoi Zingiber officinale Vitex negundo Azadirachta indica. Among the organic extracts, butanol extracts from neem leaves and seeds, and ethanolic and chloroform extracts of derris root were the most toxic. Off the water extracts, those that were very highly toxic, causing 100 percent mortality at 200 ppm, 24 HAT were the berris of Phytolacca dodecandra, bark of Entada phaseoloides and Syzigium cumini. Four principles A, B, C, and D were purified from derris crude extract. Principle C was identified as rotenone and proven to be highly toxic (100 percent mortality) to golden snails at 20 ppm. The other principles were as toxic as rotenone at 40 ppm, 48 HAT. Among the water extracts of 12 potential plants evaluated in the field, those from the roots of Derris elliptica, berries of P. dodecandra and seeds of A. indica at 90, 120, and 100 kg/ha were the most effective. Addition of base (urea) during extraction, potentiated the derris root toxicity, reducing application of 45 kg/ha. A. indica extract manifested antifeedant effect on the snails