Conserving the diversity of selected arthropods in cabbage-growing areas in Mt. Malindang, Misamis Occidental [Philippines] through participatory Integrated Pest Management

This participatory action research was conducted to stop kaingin (Swidden agriculture) at the Mount Malindang Range Natural Park (MMRNP) and minimize dependence of farmers on chemical fertilizers and pesticides. The latter was achieved by launching Integrated Pest Management (IPM) in cabbage production, which aimed to restore, improve, and maintain biodiversity and productivity of farms in the crater valleys of the two upland communities of Don Victorino, Misamis Occidental, namely, Gandawan and Lake Duminagat. Farmers preferred planting cabbage and onion because of their high market demand and price. The first field-trial showed the diamond back moth or DBM (Plutella xylostella) as the major cabbage pest. Minor pest were also identified - common cutworm (Spodoptera litura), black cutworm (Agrotis ypsilon), green peach aphid (Myzus persicae), and otiorrhynchine weevil. Pests that attack onion were cutworms, onion maggot (Liriomyza sp) and thrips (Thrips tabaci) , while the aphid, Aphis gossypii, infested sweetpepper. Both IPM and farmers' plots had higher DBM populations under monoculture than in polyculture. Beneficial arthropods were greater in IPM plots than in farmers' plots, being more diverse in Lake Duminagat; parasitism of DBM larvae and aphids was high in IPM plots but none in the farmers' plots. In the second field trial, agroforestry plots harbored more spiders than IPM plots. Farmers' plots along the slopes had much higher number of spiders because pesticide use was minimal in all plots. In the first field trial, cabbage yields in IPM plots were comparable with those in farmers' plots. In the second field trial, yield in the demo plots was highest, followed by the agroforestry and IPM plots. The lowest yields were obtained from farmers' plots. The yield difference was attributed mainly to supplemental use of chicken dung. IPM plots generally obtained the highest net income due to low production cost in terms of minimal pesticide use. However, agroforestry plot had a higher return on investment (ROI) than IPM plots because of zero pest control. The farmers' plots had the highest production cost due to high cost of chemical inputs. Better yields in the demo, agroforestry and IPM plots in the abandoned crater valley of Gandawan demonstrated that the area could still be made productive with proper IPM and crop management practices. Moreover, cabbage can be grown without pest management activities during the wet season as long as the farm has a diverse plant cover as refuge and source of food for beneficial arthropods. The study visit benefited the participating farmers and agricultural technicians. The field days showed non-participants the benefits derived from various approaches to cabbage production, especially IPM and agroforestry. Technologies and new practices like conserving beneficial organisms such as spiders, the bagging of cabbage seedlings for increased survival during transplanting, and the use of chicken dung as fertilizer supplement were recommended for adoption of upland farmers.