Effect of soil temperature and moisture on the pathogenicity of two species of entomopathogenic nematodes (Rhabditida: Steinernematidae)

摘要

Effect of soil temperature and moisture on the pathogenicity of two species of entomopathogenic nematodes (Rhabditida: Steinernematidae)This study investigated the impact of soil temperature and soil moisture on the virulence of the entomopathogenic nematodes Steinernema carpocapsae and S. feltiae. The effects of temperatures of 10, 15 and 25 °C and humidity of 6% and 12.5% were tested against the larvae of Tenebrio molitor. The nematodes were tested in two concentrations of 50 nematodes and 500 nematodes per box. S. carpocapsae was generally significantly more efficient at the highest temperature (25 °C) than S. feltiae, especially at the lower concentration of 50 nematodes per box. S. feltiae recorded higher insect mortality at lower temperatures (15 °C and 10 °C). The virulence of both tested nematode species was low (0-26%) at 10 °C after 7 days, but in the case of S. feltiae increased to 66% after 14 days. The efficacy when tested with 6% moisture at 15 °C was low (4% for both nematode species) compared with 12.5% moisture, where after seven days it reached 54% for S. carpocapsae and 70% for S. feltiae, although generally, S. feltiae was more efficient under dry conditions than S. carpocapsae. Insect mortality inreased significantly after remoistening of the soil, especially with S. feltiae (500 nematodes per box) where mortality reached 46% two weeks after remoistening.