Farmer’s behavior with insecticides used against marigold insects in Khon Kaen and Mahasarakham provinces, Thailand

Abstract

Insecticides are one of the most widely and commonly used methods for pest control. However, the overuse and misuse of insecticides have resulted in farmer and consumer health risks, as well as dangers to other living organisms and environmental pollution. Therefore, the objective of this study was to investigate the farmers’ pest management behavior in marigold cultivation in Thailand’s Khon Kaen and Mahasarakham provinces. Our results present the farmers’ behavior, classified into three categories: 1) insecticide use only; 2) no insecticide applied; 3) mixed methods of insecticides. We determined that the majority of farmers (68.42%) used only insecticides (Group 1). The highest net profit, 14,500 Baht/400 m², was found in the mixed methods of insecticides (Group 3); whereas the non-use of insecticides (Group 2) gave the highest net profit per plant of 10.25 Baht/plant, followed by Group 3 and Group 1 at 8.59 and 7.76 Baht/plant, respectively. The analyses of insecticide residues and degradation of marigold flowers were conducted in experiments under field conditions and in wholesale stores in Khon Kaen province. The application of insecticides (carbamate and organophosphate, used following their respective product recommendations) left no toxic leaf residues (MRL ≤ 5 mg/kg); whereas their application, according to the farmers’ current practices, produced toxic residues at levels over 5 mg/kg, and took 14 days for degradation. Fresh flowers, which were collected from seven wholesale stores, showed that five out of seven (71%) exceeded safe standards of insecticide residue.