BIOLOGICAL CONTROL OF OTIORHYNCHUS SULCATUS F. BY USE OF ENTOMOPATHOGENIC NEMATODES OF THE GENUS HETERORHABDITIS

Larvae of Otiorhynchus sulcatus cause serious damage to woody ornamentals, greenhouse ornamentals and fruit carrying plants all over Europe.
Especially azaleas and Rhododendron are among the prefered host plants of this species.
Pest control systems based on the use of chemical insecticides failed to obtain sufficient results under pratical conditions in horticulture, particularly in soils and substrates with high amounts of organic matter.
Different experiments were carried out in containerized woody ornamentals and in open field stands of straw- berries to test entomopathogenic nematodes (Heterorhabditis sp.) as biological control agents against larvae of O. sulcatus. The following results were obtained:

• Larvae, pupae and young adults were parasitizid by Heterorhabditis.

• At soil temperatures above 12 °C decreases in host densities between 81 % and 100 % were found as well in containerized ornamentals as in field production of strawberries

• Dosage levels could be reduced to 10 000 nematodes per 2 1-container resp. 600 000 nematodes per m² without significant loss of efficiency.

• Heterorhabditis should be applied as soon as they are delivered.
  Cool-storage for several weeks drastically reduced their efficiency.

• Soil treatments with the fungicides benomyl, fosetyl, iprodion, metalaxyl, prochloraz, propamocarb, pencycuron did not show negative effects on the efficiency of Heterorhabditis against larvae of O. sulcatus.

V International Rhododendron Conference

G.F. Backhaus

https://doi.org/10.17660/ActaHortic.1994.364.16