Use of entomopathogenic nematodes for control of grape phylloxera (Homoptera: Phylloxeridae): a laboratory evaluation
1999
English-Loeb, G. | Villani, M. | Martinson, T. | Forsline, A. | Consolie, N.
The effectiveness of 2 species of entomopathogenic nematodes was examined in the laboratory against the root-form of grape phylloxera Daktulosphaira vitifolia (Fitch). Our basic unit of measurement was survival of grape phylloxera established on root pieces of the cultivated grape Vitis vinifera L. variety 'Cabernet Sauvignon' in the presence or absence of nematodes. In petri dish trials, the Oswego strain of Heterorhabditis bacteriophora Poinar reduced survival of attached grape phylloxera by up to 80% relative to the control treatment, whereas Steinernema glaseri Steiner (isolate 326) had no measurable impact and was not used in further experiments. Hb Oswego significantly reduced survival of grape phylloxera on root pieces placed in small cups filled with soil, but only when soil moisture was high (>13% water content wt:wt) and when high densities of infective nematodes were used (>15,000/g soil). Grape phylloxera exposed to Hb Oswego often turned a brick-red color, indicating successful infection. However, we did not detect any evidence that Hb Oswego could successfully reproduce within the bodies of grape phylloxera hosts. Therefore, although Hb Oswego can exert significant mortality in the laboratory, their use in the field in an augmentative release program may be constrained by the need to use high densities, their dependence on moist soils, and their inability themselves within grape phylloxera hosts.
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