The susceptibility of the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae), to Heterorhabditis heliothidis (Nematoda: Heterorhabditidae) in the laboratory
Exposure of 4th, 5th, and 6th instar Choristoneura fumiferana to Heterorhabditis heliothidis (120 nemas per larva) resulted in 100% mortality within 48 h at 24 ± 1 °C. At 17 °C, 100% mortality was achieved within 120 h. Reduction of the dose to 15 nemas per 5th–6th instar larva caused 70% mortality at 24 ± 1 °C and 15% mortality at 17 °C within 120 h. At the higher temperature, mortalities of 80 and 73% were recorded for pupae exposed to 150 and 60 nemas per pupa, respectively. When 6th instar larvae on foliage of balsam fir or blue spruce were treated with the nematode suspension (120 nemas per larva) 100% mortality was obtained within 72 h at 24 ± 1 °C. The potential of using this nematode in biological control of spruce budworm is discussed.