Individual study: The functional significance of E-β-Farnesene: does it influence the populations of aphid natural enemies in the fields?
Cui L., Francis F., Heuskin S., Lognay G., Liu Y., Dong J., Chen J. & Song X. (2012) The functional significance of E-β-Farnesene: does it influence the populations of aphid natural enemies in the fields? Biological Control, 60, 108-112
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Use chemicals to attract natural enemies
A randomised, replicated, controlled study in 2009-2010 in Shandong, China (Cui et al. 2012) found plots with E-β-farnesene lures had 9-41 parasitised aphids/20 Chinese cabbages Brassica rapa pekinensis compared to 5-19 parasitised aphids in controls. More parasitoid wasps (Aphidiidae) occurred in plots with the chemical attractant (11-14 wasps in traps) than controls (5-10 wasps). More lady beetles occurred on cabbages in treated versus control plots (14-16 vs. 6-8 lady beetles/20 cabbages), but numbers were similar in traps (2.4-3.0 vs. 0.7-2.7 lady beetles). Spider (Araneae) numbers were similar between treated plots (26-133 spiders/20 cabbages) and controls (60-104 spiders). Fewer aphids (Aphidoidea) occurred in plots with E-β-farnesene lures than controls (167 vs. 365 aphids/20 cabbages in 2009, 1,108 vs. 1,332 in 2010). A chemical releaser was attached to a yellow pan trap in the centre of each 10 x 10 m plot and filled with 100 µl of E-β-farnesene (an aphid alarm chemical) in paraffin oil every seven days. Controls used a pan trap with no chemical releaser. Treatments were replicated three times. Invertebrates were surveyed weekly in September-October on 20 cabbages and in pan traps.