Evaluation of entomopathogenic nematode species for the control of melonworm (Lepidoptera: Pyralidae)
1995
Shannag, H.K. | Capinera, J.L.
Laboratory bioassays were conducted to determine pathogenicity of five entomopathogenic nematodes from the genera Steinernema and Heterorhabditis against melon-worm, Diaphania hyalinata (L.). S. carpocapsae (Weiser) (Mexican strain) was the most pathogenic nematode species, followed by H. bacteriophora (Poinar), S. feltiae (Filipjev), S. anomali (Kozodoi), and S. glaseri (Steiner), respectively. The LC50 for S. carpocapsae (Mexican) was 39.9 infective juveniles per milliter. The rate of nematode invasion into insects was proportional to the overall pathogenic effect of the various nematodes. The level of insect mortality and infectivity (the number of nematodes invading the insect) were directly related to exposure time. First instars and pupae were significantly less susceptible to S. carpocapsae infection than older larvae and prepupae. The number of nematodes found in the hemocoel increased with larval age. Mortality and infectivity were inversely related to nematode size. In field trials, survival of S. carpocapsae (All strain) on squash plant foliage was reduced to 0.77% within 40 h in a trial under high humidity conditions and to 0.25% after 18 h in a trial under moderate humidity conditions. Field applications of 5 billion nematodes per hectare produced infection rates of 52-55%.
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