Evaluation of entomopathogenic nematodes for the control of Mediterranean fruit fly (Diptera : Tephritidae)

The virulence of various entomopathogenic nematode (EPN) strains was evalua ted against the Mediterranean fruit fly, C. capitata. The selected nematode s were assessed for their infectivity for the final lar val stage of the in sect host and under varying environmental conditions. Among 12 EPN strains tested, Steinernema riobrave Texas (Sr TX) and Heterorhabditis sp. IS-5 (H IS-5), showed high activity and induced > 80% mortality. Six EPN strains sh owed limited activity (>30% mortality), and four strains had no effect (<20 % mortality). Sr TX was more effective than H IS-5. Mature C. capitata larv ae were most susceptible to nematode infection during the first 4 h after t hey began to emerge from their diet to pupate. Activity of the two nematode strains at a constant inoculation rate was dependent on insect larval dens ity The highest activity was recorded at 1.88 larvae cm(-2) and decreased a t higher larval densities EPN activity was also directly related to nematod e density Maximal activity was shown at a density of 150 infective juvenile s cm(-2). A similar activity pattern was also recorded with Sr TX in four d ifferent soil types. The persistence of this EPN in the soil extended over 5 days but there was no activity after 14 days Except for a lower activity under cool conditions (17 degrees C), temperatures ranging between 22 and 4 1 degrees C, or moisture levels in the treated soil ranging between 3 and 2 0%, had no significant effect on nematode activity Our results suggest that application of Sr TX against C. capitata may have potential for controllin g C. capitata.