Sensibilidade de diferentes populações brasileiras de Meloidogyne incognita a novas moléculas nematicidas

Abstract

The literature contains reports of varying sensitivity of Meloidogyne incognita populations to chemical nematicides. Given this, the objective of this study was to evaluate the sensitivity of different Brazilian populations of M. incognita to the nematicides cyclobutrifluram, fluazaindolizine, fluensulfone, and fluopyram. Eleven populations of M. incognita from different regions of Brazil were used. To determine the lethal concentration (LC50), five different concentrations were tested for each molecule and for the positive control, carbofuran. In the wells of a 96-well polypropylene plate, 20 μL of an aqueous suspension containing approximately 20 J2 of M. incognita and 100 μL of the solution of the molecules diluted with an aqueous solution of Tween® 80 (0.01%) + DMSO 1.8% (v/v) (1.5% (v/v)) were added to the wells of a 96-well polypropylene plate. The plates were then kept in an incubator at ±28 °C for 48 hours. After the exposure period, the mobility and mortality of J2 were evaluated. The test was performed in a completely randomized design, with five replicates, each molecule being evaluated individually. For the hatching test, 20 μL of an aqueous suspension containing approximately 100 M. incognita eggs and 100 μL of the diluted solution of cyclobutrifluram, fluensulfone, fluopyram, or carbofuran molecules were added to the wells of a 96-well polypropylene plate. Distilled water was used as a negative control. The plates were kept in an incubator at ±28 °C for 72 h. After this exposure period, the molecules were removed and distilled water was added. Egg hatching was evaluated cumulatively over a period of 14 days. The test was performed in a completely randomized design, with five replicates, each molecule being evaluated individually. The UFLA01 population obtained from Bahia was the most sensitive to fluensulfone, with LC50 values of 45.168 and 41.312 µg/ml. On the other hand, the UFLA09 population obtained from Tocantins showed lower sensitivity to fluensulfone, with LC50 values of 172.908 and 213.808 µg/ml. The UFLA08 and UFLA06 populations were the most sensitive and least sensitive to fluopyram and cyclobutrifluram. For the nematicide fluazaindolizine, UFLA01 was the most sensitive population, while UFLA08 was the least sensitive. Fluensulfone and fluopyram acted as good ovicides, reducing hatching in all populations. Cyclobutrifluram had effective ovicidal action at the highest concentration. Different populations of M. incognita show different degrees of sensitivity to the new nematicide molecules.