## 3 Discussion
[PERSON] and [PERSON] [45] also studied the olfactometric response of EPNs toward linalool, observing that only one strain of _Steinerrema carpoaspase_ ([PERSON]) was attracted to this compound, while strains of _Steinerrema feliae_ ([PERSON]), _Steinerema kraussei_ ([PERSON]), and _Heterorhabditis bacteriopora_ ([PERSON]) were not attracted. Our study showed that _S. australe_ was significantly attracted to two out of the five concentrations of linalool assayed. The results for 1-nonyne also showed an attractive effect on _S. australe_ at all tested concentrations. This compound has been poorly studied in terms of its potential role as a semiochemical compound, and there are no records focusing on its ability to elicit a response upon EPNs. However, its presence has been reported among the constituents of leaf volatiles of _Ficus vogelii_ Miq. (Rosales: Moraceae) [46], as well as volatile constituents from _Brassica oleracea_ var. _capitata_ L. (Brassicales: Brassicaceae) extracts. The latter was studied as an attractant to the caterpillar _Pieris rapae_ ([PERSON]) (Lepidoptera: Pieridae) [47] and as a precursor for the synthesis of a chemical cue found in the caterpillar _Spodoptera litura_ ([PERSON].) (Lepidoptera: Notuidae) to elicit prey-locating behavior in the predatory stalk bug _Eccanthecona furellata_ ([PERSON]) (Hemiptera: Pentatomidae) [48]. The terpenoid \(\alpha\)-terpineol is a frequent secondary metabolite produced by plants [49] with antimicrobial activity [50]. Moreover, several studies have determined its presence in species from the genus _Vaccinium_. For example, [PERSON] et al. [51] noted that \(\alpha\)-terpineol was synthesized by _V. corymbosum_ in response to the stress produced by UV-B radiation, as well as the major constituent of volatiles produced by stems of _Vaccinum arctostaphylos_ L. [52]. This compound was reported as a component of the stalk bug _Podisus manculventris_ [PERSON] (Hemiptera: Pentatomidae) aggregation pheromone [53] and as a component of the mountain pine beetle _Dendroctous ponderosae_ [PERSON] (Coleoptera: Curculinionidae) frass [54]. No records were found about the potential role of \(\alpha\)-terpineol on EPNs' behavior; however, the potential role of this compound on the plant parasitic nematode _Meloidogyne incognita_ (Kofoid and White) (Tylenchida: Heteroderidae) galling was reported in cotton roots [55]. The indirect root defenses of _Asclepias syriaca_ L. (Gentiananles: Apocynaceae) under the attack of the cerambycid _Tetraopes tetrophthalmus_ Forster (Coleoptera: Cerambycidae) larvae showed a significantly larger release of limonene and eucalypt than the undamaged roots, resulting in more _H. bacteriophora_ attracted and less larval survival [5]. Eucalypt was also linked to the defensive response in roots of oak trees _Quercus petraea x Quercus robur_ (Fagales: Fagaceae), which was attractive to the larvae of the cockchafer _Melolontha hipposcalani_ Fab. (Coleoptera: Scarabaeidae) [56]. Eucalypt produced by wounded roots of poplars _Populus trichocarpa_ [PERSON]. & [PERSON]. [PERSON] and _P. nigra_ L. (Malpighiales: Salicaceae) inhibited the growth of _Phytophthora catcorum_ ([PERSON] & Cohn) J. [PERSON]. (Peronosporales: Peronosporaceae) [57] showing insecticide effects against the caterpillar _Spodoptera littoralis_ (Boisduval) (Notudidae) [58]. Despite its numerous documented effects, our results did not reveal any evidence of the behavioral role of eucalypt on _S. australe_. Moreover, among the eight tested compounds, eucalypt was the only compound that did not elicit a response at the assayed concentrations. For limonene, the results were slightly different. The concentration of 10 ug mL\({}^{-1}\) attracted significantly more IJs than the control. Limonene is a well-known herbivory-induced volatile [52], whose presence was reported to induce attraction in adults of _A. supercilisus_[32] and to recruit _S. diapprepsi_ IJs in two-choice olfactometric trials [38].