species. Standard curve points were obtained from DNA dilution. Four independent DNA extractions were performed from Eppendorf tubes containing 300 IJs in 100 ml of the corresponding nematode species (Ultra Clean SoilTM DNA kit, MO BIO) to generate a standard curve [32,44]. Dilutions corresponding to 100, 30, 10, 3, and 1 IJs were prepared using serial dilution of the appropriate DNA. Nematodes from soil samples were extracted by sucrose centrifugation [59] from aliquots of 500 cm3 from the mixed composite sample. Each nematode community was concentrated in a 1.5 ml Eppendorf tube. DNA was processed using the UltraCleanTM soil DNA extraction kit and quantification was performed for each DNA extraction using the nanodrop system with the control program (ND-1000 v3.3.0). All DNA samples were adjusted to 0.2 ng/ml that is required for nematode quantification [32]. The resulting real values were analyzed with analysis of variance (ANOVA) for the EPN species recovered (F = 41, df = 5, 204). Where ANOVA showed significant differ- ences, Tukey’s HSD test (P , 0.05) was conducted to separate means in the software R (R Development Core Team 2004). Supporting Information Figure S1 (TIFF) Conversion of pregeijerene (A) to geijerene (B). Figure S2 Chromatograms showing the initial crude extract prior to purification and final purified pregeijerene. The Y-axis represents relative abundance or the ratio of a mass peak profile area to that of another. These were calculated as ratios of the sums of areas used to plot the profiles 6100%. (TIFF) Figure S3 Soil probe design used to sample volatiles below- ground. Probe is inserted into soil and connected to a vacuum pump. (TIFF) Figure S4 Chromatograms of volatiles taken from intact citrus roots in the field at one and 10 m distances from the trunk of the tree. The Y-axis represents relative abundance or the ratio of a mass peak profile area to that of another. These were calculated as ratios of the sums of areas used to plot the profiles 6100%. (TIFF) References 1. Turlings TCJ, Tumlinson JH, Lewis WJ (1990) Exploitation of herbivore- induced plant odors by host-seeking parasitic wasps. Science 250: 1251–1253. 2. Takabayashi J, Dicke M (1996) Plant-carnivore mutualism through herbivore- induced carnivore attractants. Trends Plant Sci 1: 109–113. 3. Tumlinson J, Turlings T, Lewis W (1993) Semiochemically mediated foraging behavior in beneficial parasitic insects. Arch Insect Biochem Physiol 22: 385– 391. 4. Turlings TCJ, Wa¨ckers F (2004) Recruitment of predators and parasitoids by herbivore-injured plants. In: Carde´ RT, Millar JG, editors. Advances in insect chemical ecology. Cambridge University Press. pp 21–75. 5. Kant MR, Bleeker PM, Wijk MV, Schuurink RC, Haring MA (2009) Plant volatiles in defense. In: Loon LCV, editor. 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One treatment replicate is depicted. (TIFF) 1H (600 MHz), 13C (151 MHz), HMBC and NOESY Table S1 NMR spectroscopic data for pregeijerene in C6D6.13C was also detected directly (126 MHz) using a 5 mm Cryoprobe. Chemical shifts referenced to residual proton signal in C6D6 benzene d(1H) = 7.16 ppm for 1H and d(C6D6H) = 128.2 ppm for 13C. (DOCX) Table S2 1H (600 MHz), 13C (151 MHz), HMBC and NOESY NMR spectroscopic data for geijerene in C6D6.13C was also detected directly (126 MHz) using a 5 mm Cryoprobe. Chemical shifts referenced to residual proton signal in C6D6 benzene d(1H) = 7.16 ppm for 1H and d(C6D6H) = 128.2 ppm for 13C. For convenience, the pregeijerene numbering is retained after cope rearrangement to geijerene. (DOCX) Materials and Methods S1 (DOCX) Acknowledgments We thank Dr. Peter Teal (USDA-ARS-CMAVE) for facilitating access to laboratory space and equipment. 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