Use of Meloidogyne incognita as biomonitor of cadusafos contamination in soil

The potential use of Meloidogyne incognita as biomonitor of cadusafos, an acetylcholine esterase inhibitor (AChE) was studied in 3 major Indian soils, alluvial, black and red. The availability of the toxicant in soil solution as estimated by gas chromatography. was influenced by its adsorption on to clay, being strong in black, moder.ate in alluvial and weak in red soils. This in turn adversely anffected invasion of M. incognita J2 in cowpea up to 60 days when the soils were exposed to cadusafos @ 1.0 and 2.0 pg/g soil for varying periods of time and plants grown in growth chamber providing 16 h photoperiod at 26°C and 8 h dark period at 18°C. The reduction in invasion was more in alluvial and red soils than black soil. The restriction in invasion could be well correlated with cadusafos concentration in soil solution (R = 0.69*) and predicted as Y = 23.41 54–23.10067 XI (log solution concentration) + 0.68626 X² (clay%): adjusted R² = 0.92*. Similarly, concentration of cadusafos in soil solution could be expressed as Log Y = 1.70382–0.01957 XI (invasion%) -0.0064 X2 (days) -0.0034 (sand%); adjusted R² = 0.90*. The study envisaged ample potential of M. incognita as bioindicator of cadusafos in the soil environment and also revealed that cadusafors performed better in alluvial and red soils than black soil.