## 2 Results and Discussion
### Chemical Composition of Headspace Samples from C. dactylon, C. exaltatus, and P. repens
In Figure 2A, it can be seen that the highest number of the dominating group of terpenoids could be found in the root samples of _C. exaltatus_, when compared to the root samples of the other two plant species. The lowest total numbers of detected peaks were obtained from the root samples from _P. repens_. Nonetheless, in Table 1, it can be seen that the largest relative peak area was detected in _P. repens_ across all samples. It appears that fewer VOCs originated from the torpedo grass roots compared to the other plant samples but that the roots emitted an amount represented by a higher relative area percentage of the said compounds. In Figure 2B, the distribution between substance classes detected in the shoot samples is shown. Here, it is visible that _C. exaltatus_ shoot samples contained the largest number of terpenoids of all the samples analyzed, contributing to the trend of the terpenoid class constituting the largest percentile in the overall class distribution. In Figure 1C, the Venn diagram shows the overlap of the detected compounds in the different plants. From this figure, it can be observed that the number of common compounds found between the three plants are quite similar. Six compounds were found in all three plants, while one to three compounds were shared between pairs of plants. What is apparent in Figure 1A,C is the large number of compounds detected only in the headspace of the _C. exaltatus_ samples. The larger number of compounds detected for this plant could be the basis for distinguishing the plants by family, as the more fragrant _C. exaltatus_ belongs to the _Cyperaceae_ family. Both _C. dactylion_ and _P. repens_ belong to the Poaceae family of plants, and when compared to that of _C. exaltatus_, they have a similarly low number of uniquely detected compounds in their headspace. Although grouping of plant families based on VOCs emission has been performed [28], it has not been done for the specific plants analyzed in this work. Therefore, differences and similarities based on belonging to a family can be suggested but not determined. Figure 2: (**A**)—Shows the distribution of compounds for each class detected in the root samples for the three plants. (**B**)—Shows the distribution of compounds for each class detected in the shoot samples for the three plants. TR—Terpenoid, AL—Aliphatics, BP—Benzenoid/Phenylpropanoids, C5—C5-branched compounds, NS—Nitrogen- or sulfur-containing compounds, Cyc—Cyclic miscellaneous compounds. In total, 26 compounds were detected for _C. exaltatus_ alone, where \(\beta\)-elemene and cyperene showed the highest relative area. In the headspace of _C. dactylon_, six compounds, the highest relative areas are reported for germacrene D and mestilbene, were uniquely detected. Regarding _P. repens_, only two compounds, myrtranylamine and phenylethylal alcohol, were uniquely detected. In the case of myrtanylamine, the sparse information available in the literature regarding its presence in the headspace of plants should be noted. This shows an excerpt of VOCs that separates the chemical profile of the plants from each other, and that could be a factor in why these plant species show different ovipositional strength [20]. Understanding the diversity of the compounds originating from all the graminoid plants is important for the selection of compounds to be tested as oviposition attractants. However, it is also important to investigate compounds that are shared between the headspace samples of multiple plants, and to evaluate the differences in the abundance between different plants. Compounds, such as \(\alpha\)-pinene, \(\beta\)-pinene, and limonene, have been shown to elicit antennal responses from _A. arabiensis_[29]. Moreover, it has been shown that a synthetic blend of compounds, with a naturally observed ratio, could trigger a short-range response from _A. arabiensis_ at a certain dosage [29]. Nonetheless, the same synthetic blend showed no response at higher dosages, or even provoked an avoiding response from the mosquitoes [29].