19. Duncan L, Graham J, Zellers J (2007) Food web responses to augmenting the entomopathogenic nematodes in bare and animal manure-mulched soil. J Nematol 39: 176–189. 20. Schroeder WJ (1994) Comparison of two steinernematid species for control of the root weevil Diaprepes abbreviatus. J Nematol 26: 360–362. 21. Kaya H, Gaugler R (1993) Entomopathogenic nematodes. Annu Rev Entomol 38: 181–206. 22. Gaugler R (2002) Entomopathogenic nematology. New York: CABI. 388 p. 23. Georgis R, Koppenho¨fer AM, Lacey LA, Be´lair G, Duncan LW, et al. (2006) Successes and failures in the use of parasitic nematodes for pest control. Biol Control 38: 103–123. 24. Turlings TCJ, Ton J (2006) Exploiting scents of distress: the prospect of manipulating herbivore-induced plant odours to enhance the control of agricultural pests. Curr Opin Plant Biol 9: 421–427. 25. Degenhardt J, Gershenzon J, Baldwin IT, Kessler A (2003) Attracting friends to feast on foes: engineering terpene emission to make crop plants more attractive to herbivore enemies. Curr Opin Biotech 14: 169–176. 26. Bruce T (2010) Exploiting plant signals in sustainable agriculture. In: Balusˇka F, Ninkovic V, editors. Plant communication from an ecological perspective. Springer. pp 215–227. 27. Thaler JS, Stout MJ, Karban R, Duffey SS (1996) Exogenous jasmonates simulate insect wounding in tomato plants (Lycopersicon esculentum) in the laboratory and field. J Chem Ecol 22: 1767–1781. 28. James D, Grasswitz T (2005) Synthetic herbivore-induced plant volatiles increase field captures of parasitic wasps. BioControl 50: 871–880. 29. Kaplan I (2011) Attracting carnivorous arthropods with plant volatiles: The future of biocontrol or playing with fire? Biol Control 60: 77–89. 30. McCoy C (2000) Entomopathogenic nematodes and other natural enemies as mortality factors for larvae of Diaprepes abbreviatus (Coleoptera: Curculionidae). Biol Control 19: 182–190. 31. El-Borai FE, Campos-Herrera R, Stuart RJ, Duncan LW (2011) Substrate modulation, group effects and the behavioral responses of entomopathogenic nematodes to nematophagous fungi. J Invertebr Pathol 106: 347–356. 32. Campos-Herrera R, Johnson EG, El-Borai FE, Stuart RJ, Graham JH, et al. (2011) Long-term stability of entomopathogenic nematode spatial patterns in soil as measured by sentinel insects and real-time PCR assays. Ann Appl Biol 158: 55–68. 33. Campos-Herrera R, El-Borai FE, Stuart RJ, Graham JH, Duncan LW (2011) Entomopathogenic nematodes, phoretic Paenibacillus spp., and the use of real time quantitative PCR to explore soil food webs in Florida citrus groves. J Invertebr Pathol 108: 30–39. 34. Johnson SN, Murray PJ (2008) Root feeders. Cambridge, MA: CABI. 226 p. 35. van Dam NM, Heil M (2011) Multitrophic interactions below and above ground: en route to the next level. J Ecol 99: 77–88. 36. van Dam NM (2009) Belowground herbivory and plant defenses. Annu Rev Ecol Evol Syst 40: 373–391. 37. De Deyn GB, van Ruijven J, Raaijmakers CE, de Ruiter PC, van den Putten WH (2007) Above- and belowground insect herbivores differentially affect soil nematode communities in species-rich plant communities. Oikos 116: 923–930. 38. Green TR, Ryan CA (1972) Wound induced proteinase inhibitor in plant leaves: a possible defense mechanism against insects. Science 175: 776–777. Subterranean Volatile Increases Biological Control 39. Haukioja E, Hakala T (1975) Herbivore cycles and periodic outbreaks. Formation of a general hypothesis. Rep Kevo Subarctic Res Stat 12: 1–9. 40. Khan ZR, Ampog-Nyarko K, Chilishwa P, Hassanali P, Kimani S, et al. (1997) Intercropping increases parasitism of pests. Nature 388: 631–632. 41. Birkett MA, Campbell CAM, Chamberlain K, Guerrieri E, Kick AJ, et al. (2000) New roles for cis-jasmone as an insect semiochemical and in plant defense. Proc Natl Acad Sci USA 97: 9329–9334. 42. Ockroy M, Turlings TCJ, Edwards P (2001) Response of natural populations of predators and parasitoids to artificially induced volatile emissions in maize plants (Zea mays L.). Agr Forest Entomol 3: 201–209. 43. Hunter M (2002) A breath of fresh air: beyond laboratory studies of plant volatile–natural enemy interactions. Agr Forest Entomol 4: 81–86. 44. Torr P, Spiridonov SE, Heritage S, Wilson MJ (2007) Habitat associations of two entomopathogenic nematodes: a quantitative study using real-time quantitative polymerase chain reactions. J Anim Ecol 76: 238–245. 45. Holeva R, Phillips MS, Neilson R, Brown DJF, Young V, et al. (2006) Real-time PCR detection and quantification of vector trichodorid nematodes and Tobacco rattle virus. Mol Cell Probes 20: 203–211. 46. Kolb S, Knief C, Stubner S, Conrad R (2003) Quantitative detection of methanotrophs in soil by novel pmoA-targeted real-time PCR assays. Appl Environ Microb 69: 2423–2429. 47. El-Borai F, Brentu C, Duncan LW (2007) Augmenting entomopathogenic nematodes in soil from a Florida citrus orchard: non-target effects of a trophic cascade. J Nematol 39: 203–210. 48. Koppenho¨fer AM, Fuzy EM (2004) Effect of white grub developmental stage on susceptibility to entomopathogenic nematodes. J Econ Entomol 97: 1842–1849. 49. Denno RF, Gruner DS, Kaplan I (2008) Potential for entomopathogenic nematodes in biological control: A meta-analytical synthesis and insights from trophic cascade theory. J Nematol 40: 61–72. 50. Hare J (2011) Ecological role of volatiles produced by plants in response to damage by herbivorous insects. Annu Rev Entomol 56: 161–180. 51. Hallem EA, Dilman AR, Hong AV, Zhang Y, Yano JM, et al. (2011) A sensory code for host seeking in parasitic nematodes. Curr Biol 21: 377–383. 52. Rasmann S, Ali JG, Helder J, van der Putten W (2012) Ecology and evolution of soil nematode chemotaxis, J Chem Ecol In press. 53. Lapointe SL, Shapiro JPT (1999) Effect of soil moisture on development of Diaprepes abbreviatus (Coleoptera: Curculionidae). Fla Entomol 82: 291–299. 54. Stover E, Castle W (2002) Citrus rootstock usage, characteristics, and selection in the Florida Indian River region. HortTechnology 12: 143–147. 55. Kaya HK, Stock SP (1997) Techniques in insect nematology. In: Lacey, LA, editor. Manual of techniques in insect pathology. London, UK: Academic Press. pp 281–324. 56. Kuzovkina I, Szarka S He´thelyi, E´ (2009) Composition of essential oil in genetically transformed roots of Ruta graveolens. Russ J Plant Physl 56: 846–851. 57. Kubeczka K, Ullmann I (1980) Occurrence of 1, 5-dimethylcyclodeca-1, 5, 7- triene (pregeijerene) in Pimpinella species and chemosystematic implications. Biochem Syst Ecol 8: 39–41. 58. Larkin MA, Blackshields G, Brown PN, Chenna R, McGettigan PA, et al. (2007) Clustal W and Clustal X version 2.0. Bioinformatics 23: 2947–2948. 59. Jenkins W (1964) A rapid centrifugal-flotation technique for separating nematodes from soil. Plant Dis Rep 48: 692. PLoS ONE | www.plosone.org 8 June 2012 | Volume 7 | Issue 6 | e38146