Motility and Migration of Nematodes in Saline Environments

Abstract

Plant parasitic nematodes cause severe agricultural damage in Northeast Brazil. Additionally, soil salinization, especially in the semiarid region of the Northeast, is another factor that limits crop yield. The study evaluated the motility of Meloidogyne enterolobii and Pratylenchus coffeae, and the vertical migration of P. coffeae under saline conditions. Motility was assessed by submitting juveniles of the second stage of M. enterolobii and juveniles and adults of P. coffeae to saline solutions of NaCl, CaCl2, and MgCl2 at concentrations of 0.00, 0.25, 0.50, 0.75, and 1.00 M, and in a mixed solution (combination of the three salts in a 7:2:1 ratio) at 2, 4, 6, and 8 days of exposure. The migration of P. coffeae was studied in segmented columns of 10 cm in length and 4.40 cm in internal diameter, filled with saline soil (mixture of NaCl, CaCl2, and MgCl2) and non-saline, whose evaluations were carried out at 2, 4, and 6 days after soil infestation. The motility and number of active juveniles of both nematodes reduced with increasing saline concentration. From 0.50 M, M. enterolobii activity was not observed in any of the exposure periods to NaCl and CaCl2. The increase in the concentrations of NaCl, CaCl2, and MgCl2 exponentially reduced the number of active P. coffeae, decreasing its activity from 0.75 M. The vertical migration of P. coffeae in the soil was negatively affected by salinity, presenting a more uniform distribution in the non-saline soil.