Aquatic faunal abundance and diversity in relation to regimes of synthetic and natural pesticides in rice fields of Central Thailand | |
| Author | Suthamma Maneepitak |
| Call Number | AIT Diss. no.NR-15-01 |
| Subject(s) | Rice--Diseases and pests--Thailand, Central Pesticides--Application--Thailand, Central |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Natural Resource Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. NR-15-01 |
| Abstract | Fauna inhabiting rice fields (many species perform important ecosystem services) is, however, increasingly threatened by pesticide uses.Forty conventionally and thirty one organically managed farms were visited in Ayutthaya and Ang Thong provinces of central Thailand to indicate pesticide use,abundance and diversity of aquatic faunaand assess the effects of pesticides on non-target organisms in wetland rice environment. Information on types and levels of pesticides used, and indices describing pesticide ‘toxic exposures’ were provided and calculated. Plankton, aquaticmacro-invertebrates, fishes,waterfowl,soil organic carbon (SOC), nitrogen (SN), rice densities and sizes were investigated in the dry and wet seasons. Using multivariate statistics interrelationships among variables were investigated. SOC was positively correlated with ‘toxic exposure’ levels, probably resulting from effects of pesticides on carbon-reducing processes. Additionally, molluscicides and herbicides explained SOC levels. SN varied spatially probably resulting from flooding regimes; management influences were unnoticeable.Phytoplankton was lowered under exposures to herbicides and natural insecticides. Zooplankton (except amoeboids) was unaffected or increased on pesticide-exposed fields, probably suffering lower predation. Bio-physical aspects partly explained abundance/diversity of aquatic insects, but abundance/diversity were generally higher on fields treated with natural rather than synthetic insecticides. Fishes and waterfowl tended to be less abundant on fields exposed to synthetic insecticides and herbicides.Application of molluscicides for controlling golden apple snailsin paddy is now declining in Thailand due to effective biological agents as Open billed-stock and ducks.Questionnaire survey was conducted in six provinces of central Thailand where 150 farmers were interviewed to investigate GAS control methods and factors related molluscicide use. Logistic regression was used to investigate interrelationship among variables. Data on age, education, training, flood, size plot, outside, land to labor ratio were recorded. Training, network of trained farmers and floods influenced the use of molluscicides by changing attitude of farmers on pest control with more adoptions on natural molluscicides and cultural control. Farmers who own small plots of land significantly use natural molluscicides. The reason might imply poorer economic situation ofsmall scale farmers through lower price of natural molluscicides and intensive use of family labors. |
| Year | 2015 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. NR-15-01 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Development and Sustainability (DDS) |
| Academic Program/FoS | Natural Resources Management (NRM) |
| Chairperson(s) | Jourdain, Damien; |
| Examination Committee(s) | Cochard, Roland ;Shivakoti, Ganesh P. ;Kumar, Prabhat; |
| Scholarship Donor(s) | Ministry of Agriculture and Cooperatives,Thailand; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2015 |