Setal anomalies in the tropical earthworms Drawida willsi and Lampito mauritii exposed to elevated concentrations of certain agrochemicals: An electron micrographic and molecular docking approach

Abstract

Abstract Setae are the functional organelle in the earthworms which act as anchors and thus are crucial for locomotion. Structural anomaly or loss of setae could result in significant functional loss in these animals. The present study reports novel observation on setal anomalies in two tropical earthworms, Drawida willsi and Lampito mauritii exposed to elevated concentrations of the agrochemicals, monocrotophos, glyphosate, urea, phosphogypsum (PG) and paper mill sludge (PMS) in soil. Three concentrations of monocrotophos (1.0, 2.0, 3.0 g/kg soil), glyphosate (0.1, 0.15, 0.2 g/kg soil), urea (0.5, 1.0, 1.5 g/kg soil), PG (50, 100, 150 g/kg soil) and PMS (5, 10, 15 g/kg soil) were used as per recommended agricultural doses and the animals were exposed for 24 h in treated soils to observe their effects on the setae. Scanning electron microscopic images revealed various setal structural deformities in both the worms. Urea had the maximum deleterious impact relative to other test chemicals. Computational analysis indicated that the high binding affinity of urea with the chitin of setae was responsible for the maximum conformational changes in the later. Setal anomalies could be used as early signal markers to evaluate soil toxicity.