Genetically modified (GM) corn in the Philippines : Ecological impacts on agroecosystems, effects on the economic status and farmers’ experiences

Mabutol-Afidchao, M.B. (2013)

Doctoral Thesis

To seek answers to the issues on GM corn adoption in the Philippines, the thesis focused to find answers on the general question: How can genetically modified (GM) corn and its attributed changes in agricultural practices affect the agro-ecosystem's biodiversity and the economic status and social life of the farmers? Survey of Asian corn borer (ACB) in Chapter2 showed that Bt corn efficiently reduce borer pest problem and damage to plants by 44%. No secondary pest outbreak was found in Bt cornfields yet, occurrence of ACB though at an insignificant level, could imply potential development of Bt toxin resistance. On biodiversity (Chapters3 and 4), the total invertebrate abundance, surface dwellers and soil dwellers were significantly higher in non-GM cornfields than in Bt and BtHT cornfields. Insecticide-sprayed non-GM cornfields harbored more invertebrates than unsprayed Bt or BtHT cornfield. Surveyed cornfields with a minimum of two years cultivation of GM corn manifested that non-Bt cornfields had significantly higher abundance and species richness of non-target invertebrates than the Bt and BtHT fields. On economic aspect (Chapter5), the non-GM corn was not statistically different from Bt, BtHT and HT corn in terms of production output(PO), net income(NI), production-cost ratio(M) and return on investments(ROI). Results of econometric and Blinder-Oaxaca analyses demonstrate that at present GM corn hybrids do not explicitly manifest economic advantage compared to non-GM corn. On social aspect (Chapter6), GM corn adoption proved to be influenced by the perceived economic advantage, extent of knowledge, level of satisfaction and extent of first-hand experience. The foremost reason for not adopting GM corn was the cost of seed. Herbicide-tolerant (HT) corn, Bacillus thuringiensis (Bt) corn, BtHT corn, abundance, species richness, Asian corn borer, secondary pest, genetically modified (GM) corn, non-GM corn, farm economics, decomposition analysis

• Bacillus thuringiensis (Bt) corn
• Herbicide-tolerant (HT) corn
• BtHT corn
• Decomposition analysis
• Farm economics
• Non-GM corn
• Genetically modified (GM) corn
• Secondary pest
• Asian corn borer
• Species richness
• Abundance

• All authors: Mabutol-Afidchao, M.B.
• Supervisor: Snoo, G.R. de
• Co-supervisor: Musters, C.J.M.
• Qualification: Doctor (dr.)
• Awarding Institution: CML, Faculty of Science, Leiden University
• Date: 2013-11-20
• ISBN (print): 9789462034693