Organic Vermicide for Safer Management of Giant Earthworms in the Ifugao Rice Terraces, the Philippines

The crude extracts from stem barks of Pittosporum pentandrum (Blanco) Merr., Albizia julibrissin Durazz., and Albizia lebbeck (L.) Benth. were tested singly and in combination against the giant earthworms (Pheretima sp. Kinberg) infesting the Ifugao rice terraces causing water seepage and collapse of rice paddy walls. Laboratory assay revealed that all plant extracts used singly or in combination caused dose-dependent vermicidal effect causing 100% mortality to giant earthworms within 5–35 min. Field trials showed that at 100 mL/L crude extracts from the species used singly or combined effectively control giant earthworms within 2–6 h. The use of the organic vermicide from the above species, as demonstrated in this study, exhibits their potential as a safer way of managing destructive giant earthworms than synthetic chemicals.