Biological and other alternative control methods against the woolly beech aphid <Emphasis Type="Italic">Phyllaphis fagi</Emphasis> L. on beech <Emphasis Type="Italic">Fagus sylvatica</Emphasis> seedlings in forest nurseries |
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| Authors: | Trine Iversen Susanne Harding |
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| Institution: | (1) Department of Ecology, Zoology Group, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark |
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| Abstract: | Biological and other alternative control methods were tested against the woolly beech aphid (Phyllaphis fagi). Field applications of mineral oil to the egg stage reduced initial aphid population by 75%, but only when the eggs were exposed to oil close to the time of hatching. Earlier oil treatments had no effect. Bioassays with the insect pathogenic fungus Lecanicillium lecanii (Verticillium lecanii) in the commercial formulation Vertalec® were conducted using different dosages, i.e. 1 × 106 ml?1 (recommended dosage) and 2 × 107 ml?1. Both nymphs and adults were susceptible to fungal infection at both dosages. The existence of a dense wax-covering in adult P. fagi had no protective effect against fungal infection. In bioassays where leaves were treated with the recommended dosage of Vertalec, there was no difference in mortality measured after 14 days between adult P. fagi with an intact wax-layer and adult P. fagi where the wax-layer had been removed. In semi-field trials with two L. lecanii treatments at the recommended dosage, the aphid population was reduced. There was no enhanced effect with the addition of an additive to the fungal suspension or from covering the plants with a polypropylene cover. The results reveal potential alternative control methods against P. fagi populations. However, adequate control with L. lecanii probably requires several treatments as opposed to the two that were tested in the present experiment. Furthermore, efficiency may depend on summer temperatures and humidity. |
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| Keywords: | Biological control Lecanicillium lecanii (Verticillium lecanii) Mineral oil Nursery pests Phyllaphis fagi |
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