Efeito do tempo e da temperatura de incubação de juvenis do segundo estádio (J2) no teor de lipídio corporal e no parasitismo de Meloidogyne javanica em soja

Abstract

The environmental temperature and the body lipid content of second stage juveniles (J2) of Meloidogyne javanica affect its parasitism on the host. So, in this work, it was studied the relationship of body lipid content and temperature with incubation period in water of J2 of M. javanica from 2 to 12 days, and the parasitism in soybean. The body lipid content of J2 decreased significantly from 2 to 12 days of incubation. However, the pathogenicity of J2 was kept until 12 days of incubation, with reduction of 67,36%, 82,75% and 86,09% on the number of penetrated J2, females and eggs mass, respectively. In another assay, J2 were incubated in water for 20 days at constant temperatures of 5°C, 10°C and 28°C, and at varied temperatures of 10 h at 5°C or 10°C and complemented with 14 h at 28°C. Every 5 day incubation, J2 pathogenicity was evaluated by inoculating them in soybean. Increase on incubation period of J2 of M. javanica at continued temperatures of 5 and 28°C reduced penetration, numbers of females, egg mass, total of eggs and eggs per gram of root. The continued incubation of J2 at 10°C per any period of time did not affect penetration and gave slow reduction during 20 days-incubation on number of female and reproduction. When J2 were exposed to 28°C per 14 h, the assessed variable behavior alike to the continued exposure to 28°C per 24 h.