## 3 Discussion
The major representatives (more than 4.00%) were pyridine (3.10% \(\pm\) 0.07), (Z)-3-hexen-1-ol (16.48% \(\pm\) 0.31), (E)-3-hexen-1-ol acetate (19.99% \(\pm\) 0.01), _p_-cymene (4.96% \(\pm\) 0.02), _(E)_-\(\alpha\)-bergamente (4.15% \(\pm\) 0.19), \(\beta\)-caryophyllene (11.30% \(\pm\) 0.27) and laboda-8(20),13(16),14-triene (4.89% \(\pm\) 0.09), which may be found in other, various species like _Lavandula angustirolia_ Mill. [24], _Coriandrum sativum_ L. [25], _Mentha pipertia_ L. [26], _Cannabis sativa_ L. [27] and _Boletus edulis_[28]. Especially interesting was high content of (_E_)-\(\alpha\)-bergamotene, which is characteristic for _Citrots bergamita_ Risso fruit [29] and pyridine, which was reported in similar amounts in _Cicer arietin_ L. [30]. The role of volatiles attracting insects, which constitute food for _Sarracenia_ plants, is not well recognized. There are only suppositions that these substances are of crucial importance. According to [PERSON] et al. [31], insects are attracted to the _Nepenthes_ pitcher opening by a combination of both the visual pattern and the sweet substances produced within the pitcher. It must be further investigated whether the volatiles produced affect prey animals. Such a trial was conducted by [PERSON] et al. [13], who delivered a comprehensive catalogue of chemical constituents of _Sarraceniaceae_ and examined the extent to which the known phylogenetic information explains the chemical composition of the plants. _Sarracenia_ plants display a huge variety of unique compounds which are found only in their lid and/or pitcher. Various compounds found in _Sarracenia_ have also been reported as attracting insects, including volatiles, flavonoids, phytochemicals and the pitcher fluid compositions [13]. Our research is a step further as we tried to determine how the plant as well individual chemical compounds affected the tested insects. We chose two highly different insects in order to compare their response to _Sarracenia_ plants. As far as flies are concerned, other authors repeatedly report that different species are trapped by different _Sarracenia_ species [18]. Therefore, we chose _Drosophila hydei_, which is described as the model for studies on the architecture of olfactory behaviour [32] and as possible prey for _Sarracenia_[33]. At the same time the possible response of aphids to carnivorous plants had not been described yet. In the first part of the experiment flies and aphids were incubated with plants. Flies were effectively attracted to the plants funnels and digested in almost 100%, while aphids response was much weaker. Only about 20% of the latter insects were attracted and digested by _S. alata_. It is possible that aphids were trapped more accidentally than flies. The results of different field studies [18; 34] confirm that Diptera are a significant constituent of the diet of carnivorous species. The specific environmental adaptation that allows plants to use animal feed is also a natural factor regulating the occurrence of certain insects. Considering the low specialization of _Sarracenia_ plants, they can be used as a biological means to fight unwanted organisms. In nature, _Sarracenia_ is not particularly effective in catching items of prey [18], but in closed facilities, such as greenhouses, tunnels or garden orangeries, these plants can become a solution to problems with some pests, for example certain flies from the family of the Sciaridae. Similar suggestions, regarding the possibility of using plants or their extracts as protective agents, were made for maize [35; 36] or mossy sorrel [37; 38]. From the compounds found in _S. alata_ we chose pyridine for olfactometric study. It reveals that pyridine attracts the Mexican fruit fly [39]. Correspondingly, in other experiments pyridine compounds were used to increase trap capture of thrips [40]. To our knowledge, the experiment mentioned was the first attempt at using pyridine in olfactometric studies on insects.