a case study from Pathum Thani province Suwanna Whangthongtham creator Waibel, Hermann Chairperson Yakupitiyage, Amararatne Examination Committee Athapol Noomhorm Examination Committee The Government of The United Kingdom Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1990 continuing eng 132 p. Th e economi c and environmental implications of two alternative citrus production systems were studi ed in two farms in Pathum Thani province. The investigation focused on the economic and environmental factors as affected by t h eir pest contro l practices ( c hemical pesticide and neem mixture extract). Measured of the economic and history performance of the farms were described and analysed. The economics of using neem mixture extract as a means of controlling pest was condu cted by counting the pests population on both farms. The environmental implication of using the different pesticides was described by the water quality, pesticide residues and a bioassay experiment of n eem. The soc i a l costs associated with the pest control practices were based on the results of a s u rvey on health hazards a mong the farmer population in Pathum Thani province. The study indicated that the main objective of a famer using chemic als is to maximize the Gross Margin resulting from his intensive man agement, while that of the n eem farmer is mo re oriented towards sustainability of the production system while achieving a specific level of Gross Margin. Neem mixture extract was significantly effective in controlling the pest such as leaf miners (Phyllocnitis citrella) at 1-4 days after spraying. Spiders were abundantly found in t he neem mixture farm, but were rarely observed in the ch emical farm. Most of the water quality parameters in both farms were similar, but the chemi cal pesticides residu es remaining in the water and fish were evident. This has implications as regards to the s uit ability of raising fish in the che mi cal orchard considering its possible e ffects on human heal th. Taking into consideration information from an opinion survey a mong aquaculture experts using delphi technique, Nil e tilapia (Tilapia n ilotica ) could be an appropriate species for introduction to the neem mixture extract farm. The health hazard· s urvey in the main citrus cultivation area showed that the chemicals used in citrus production are hazardous to the user's health. Social costs occur as medical fees and opportunity cost of labor. These cost will be saved by the society as a whole if a h armless pesticide such as the neem mixture extract will be use d on a larger scale. A thesis submitted in partial fulfilment of the requirements of the degree of Master of Science, School of Environment, and Development Thesis (M.Sc.) - Asian Institute of Technology, 1990 Citrus fruits Thailand Pathum Thani Research Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B18280 http://203.159.5.9/ait-thesis/detail.php?q=B18280 111005 20260818094518.0