Individual study: Using synthetic herbivor-induced plant volatiles to enhance conservation biological control: field experiments in hops and grapes
James D.G., Castle S.C., Grasswitz T. & Reyna V. (2005) Using synthetic herbivor-induced plant volatiles to enhance conservation biological control: field experiments in hops and grapes. Second International Symposium on Biological Control of Arthropods, September 12-16, 2005, Davos, Switzerland, Vol 1, 192-205.
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Use chemicals to attract natural enemies
A randomised, replicated, controlled trial in 2004 in Washington State, USA (James et al. 2005) found more parasitic wasps from the genus Metaphycus in vineyard blocks baited with three chemical treatments (averaging 12-25 wasps/shake sample/week) than in unbaited controls (8 wasps). Chemicals attracted more wasps from the genus Anagrus than controls in 1-3 of the five months, but numbers were only greater in all three treatments in September (approximately 260-290 vs. 170-175 wasps/trap/week). A replicated, paired, controlled trial found hops Humulus lupulus with methyl salicylate had 3-5 times more predatory insects than unbaited hops. Hops with a low methyl salicylate deployment rate had more predators vs. hops with high deployment (106 vs. 46 predators/shake sample/week). Pest spider mites (Tetranychidae) briefly exceeded spraying thresholds in baited but not unbaited hops. Predators were scarce in vineyards but some groups, including hoverflies (Syrphidae), lacewings (Chrysopidae) and lady beetles Stethorus spp., were more numerous in baited than unbaited vineyards. The first study compared methyl salicylate, methyl jasmonate and (Z)-3-hexenyl acetate treatments with unbaited controls, replicated in three 8 x 30 m vineyard blocks. The second study tested methyl salicylate at rates of 0, 180 and 516-556 dispensers/ha in hops and vineyards.