Bioassays of the nematicides MK-166 and oxamyl in the root-knot nematode, Meloidogyne incognita

Investigations were carried out on the nemastatic effects of nematicides (MK-166 and oxamyl) on embryonic development, larval emergence from egg masses, and egg-laying activity of female adults of the root-knot nematode, Meloidogyne incognita. The embryonic development of eggs laid in equilibrated saline solution was more retarded by MK-166 (88-350 ppm) than by oxamyl for the same dosage of the product. Seasonal variations of the susceptibility should be taken into account for the evaluation of the chemicals. The larval emergence from egg masses was more inhibited by MK-166 (88-350ppm) than by oxamyl. The egg masses should be, exposed to the chemicals for at least 2 weeks. Both chemicals most affected the development of nematodes 6 to 10 days after the penetration to host plants at 18.4°C, bringing about the highest depression of egg-laying activity of the females.