INSTAR SUSCEPTIBILITY OF SIMULIUM-VITTATUM (DIPTERA, SIMULIIDAE) TO THE ENTOMOGENOUS NEMATODE NEOAPLECTANA-CARPOCAPSAE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 13  (1) , 1-5
Abstract
Laboratory bioassays showed that the susceptibility of S. vittatum to N. carpocapsae increased with successive larval instars. First, 2nd and 3rd instar larvae were resistant to infection; 7th instars were highly susceptible. Significant differences in intra-instar susceptibility also were evident, as mortality ranged from 58% for the smallest 7th instar larvae to 97% for the largest. Dissections revealed that the basis for the resistance of early instars was physical exclusion of the comparatively large nematodes. The principle factor regulating the susceptibility of mid and late instars was injury to nematodes caused by larval mouthparts during ingestion. Differences in intra-instar susceptibility were similarly related to nematode injury.