Managing invasive pest species and the Farmer Field School approach

摘要

The spread and damage caused by the coconut leaf beetle, B. longissima (Gestro) (Coleoptera: Chrysomelidae: Hispinae) in Asia and the Pacific highlights the dangers of invasive species on coconut and native palms. The insect is believed to be transported unwittingly in coconut planting materials or ornamental palms from forests. Once it arrives undetected, the paucity of effective natural enemies leads to the rapid spread of an aggressive pest that threatens the coconut industry and, indeed, the survival of ornamental palms. The coconut leaf beetle is an invasive species that can be managed by the introduction of effective parasitoids. Two documents need to be considered in approaching the management of an invasive pest species: The International Standards for Phytosanitary Measures (ISPM), Nos. 2 and 3. The first document allows an analysis of the nature of the pest and if classical biological control is necessary, ISPM No. 3 provides a code of conduct that will minimize the risk of introduction of effective natural enemies. However, following the ISPM is only a first step and should be complemented by efforts for quality farmer education using the participatory Farmer Field School (FFS) approach. The need for FFS is clearly discussed in the case study of a classical biological control of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) in Southeast Asian countries such as Malaysia, the Philippines and Viet Nam. The successful introduction and establishment of Diadegma semiclausum (Hellen) (Hymenoptera: Ichneumonidae) was effected by educating farmers about the harmful effects of spraying on the survival of beneficial agents. In Malaysia, lack of farmers' education led to a 12-year wait before the impact of the parasitoid could be realized because farmers continued to spray at two-day intervals and thus hampered any effort to establish the parasitoid. Indeed, often the use of insecticides contributed to the problem instead of being a solution. Learning from the Malaysian and Philippines' experience, biological control of P. xylostella was achieved in six months in Viet Nam, following a concerted effort to teach farmers about biological control. Indeed, it is recommended that any classical biological control programme should have concomitant FFS efforts. Similarly, it is envisaged that an FFS effort will provide the means for farmers to sustain management of key pests of coconuts, such as the rhinoceros beetle, Oryctes rhinoceros (L.) (Coleoptera: Scarabaeidae) and Artona catoxantha (Hampson) (Lepidoptera: Zygaenidae). Incorporating the FFS approach into a classical biological control provides a good learning opportunity for farmers to discover the complex issue of biological control. Perhaps, for the first time, farmers will learn about the rich biodiversity that keeps most pest species in check. Farmers will become custodians of the biological control agents and ensure that these will continue to keep pest populations at bay.