In previous studies using wheat and brachiaria grass, we observed that the use of thiamethoxam directly affects nitrogen metabolism [5] and [25], which is the main constituent of the synthesis of amino acids, containing glutamate (GLU) as the first amino acid synthesized [26]. GLU is the precursor of the synthesis of the tetrapyrrole ring, the main structural component of chlorophyll pigments [27], justifying the modifications in the contents of these pigments.