Physiological effects of thiamethoxam on Zea mays and its electrochemical detection using a silver electrode

The aim of this work is the detection and quantification of bioaccumulated thiamethoxam (THM) in Zea mays at a silver electrode using square-wave voltammetry. Thiamethoxam bioaccumulation and plant development were followed for 10 days from germination to seedling growth. Germination rate, accumulation rate, root length, and plant length were used as indicators. All experiments were carried out using several concentrations of THM (5.0 × 10^-4 , 1.0 × 10^-3 , 5.0 × 10^-3 , 3.4 × 10^-2 and 5.0 × 10^-2 mol L^-1 ).

The results confirm that Zea mays was sensitive to this insecticide and that germination and growth inhibition were dose dependent. The efficiency and utility of the proposed method were discussed. The current intensity increases linearly with an increase in the THM bioaccumulated in Zea mays. After 10 days,the recovery results of the extraction of THM from zea Mayes samples spiked with different concentrations were encouraging. The detection and quantification limits were found to be 9.58 × 10^-6 mol L^-1 (3*SD/B) and 3.13 × 10^-5 mol L^-1 (10*SD/B). The precision was 2.67% for eight repetitions in a solution of 3.5 × 10^-4 mol L^-1 THM. Histological tests were also performed to confirm the effect of THM on the plant and showed that exposure to THM induced a net histological modification in the primary root tissue of Zea mays.

The use of THM can affect the quality of the plant crop yield, and its accumulation in edible plants could pose a potential risk for human and animal health if the insecticide intake were to exceed the recommended tolerable limits. © 2019 Society of Chemical Industry.