The attack density of the spruce beetle, Dendroctonus rufipennis (Kirby), was reduced to 10-25% of that on untreated felled Engelmann spruce (Picea engelmannii) trees, when the trees were treated with 9-15 bubble cap release devices, each releasing the aggregation inhibitor MCH at 1-3 mg/24 h at 20°C. In the first experiment, deterioration of many release devices reduced the suppression effect. In the second experiment, MCH reduced attacks by 85%, and total brood production by 79-88%. The attacks on the MCH treated trees occurred late, as evidenced by the early stage of development of galleries and brood on these trees. Semiochemical-baited traps at untreated, or MCH-treated, felled trees caught few beetles, and had no effect on the attack density. The results show that manually applied MCH can be used operationally to reduce attacks by the spruce beetle on small groups of wind thrown trees. Mass trapping of spruce beetles is not feasible with currently known semiochemicals. West. J. Appl. For. 4(2):49-52, April 1989.
The attack density of the Douglas‐fir beetle, Dendroctonus pseudotsugae, was reduced to 3–7% of that on untreated Douglas‐fir trees, Pseudotsuga menziesii, when the trees were treated with bubble cap release devices releasing MCH at 3 mg/24 h stapled to the tree trunk at 3 m intervals. Density dependence of brood development suggests that brood emergence was not as dramatically affected by the MCH. Lindgren funnel traps baited with aggregation pheromones did not significantly affect attack density.
Zusammenfassung
Zur Wirkung von MCH und Lindgren‐Pheromonfallen auf den Befall gefällter Douglas‐Tannen durch Dendroctonus pseudotsugae
Die Befallsdichte von D. pseudotsugae bei gefällten Douglas‐Tannen (Pseudotsuga menziesii) wurde auf 3–7% der Dichte‐Werte an unbehandelten Stämmen reduziert, wenn die gefällten Stämme mit MCH abgebenden (3 mg/24 h) Gummibechern in 3‐m‐Abständen bestückt wurden. Die Borkenkäferbrut wurde durch die MCH‐Freisetzung nicht wesentlich beeinflußt. Lindgren‐Trichterfallen, die mit Aggregations‐Pheromonen beködert waren, zeigten keinen signifikanten Einfluß auf die Befallsdichte der Käfer.
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