Organophosphate and carbamate pesticides are used to control pests in agricultural industry and home gardening. These toxic compounds operate through inhibiting the enzyme acetylcholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely, and causing various symptoms such as weakness and paralysis. Monocrotophos is an organophosphate insecticide, which is highly toxic to birds and human beings. Totally 57 dead doves were sent to the Seoul Metropolitan Government Research Institute of Public Health & Environment for further examination. All of the carcasses were found in Gwanak-gu two times, 18 doves on 7 August 2012 and 39 doves on 1 October 2012 respectively. Gross examinations revealed no evidence of any specific disease condition. The contents of gastrointestinal tracts contained residues of monocrotophos ranged from 600.57 to 749.2 mg/kg in 18 dead doves and 5,064 mg/kg in 39 dead doves. Based on these evidences, we conclude that the doves died due to monocrotophos poisoning after taking the food contaminated by monocrotophos. It was assumed that a misuse and an abuse case of commonly used pesticides in Korea.

Molecular mechanisms of monocrotophos resistance in the two-spotted spider mite (TSSM), Tetranychus urticae Koch, were investigated. The resistant (AD) strain showed ca. 3,565-fold resistance compared to a susceptible (UD) strain. No significant differences in the esterase and gluthathion-S-transferase activities were found between two strains whereas AD showed a 1.9-fold higher mixed function oxidase activity. Acetylcholinesterase (AChE) inhibition assay revealed that the AChE from AD strain is 91-fold less sensitive to monocrotophos, suggestive of the target site insensitivity mechanism. Three point mutations (G228S, A391T and F439W/Y) in the AChE gene (tssmace) appeared to primarily contribute to the reduced sensitivity of AChE as judged by the correlation study of mutation frequency versus resistance levels (LC50) of several field populations. The resulting correlation coefficients of the G228S and F439W mutations were 0.711 and 0.300, respectively, suggesting that G228S mutation may play a more significant role in resistance. The A391T mutation, saturated in all field populations examined, appears to provide a base line resistance.