## 1 Introduction  
The consequences of human activity in agriculture have been the introduction and naturalization of new plant species in many regions of the world. This in turn has increased the likelihood of new plant invasions, which brings negative consequences to the ecologies of endemic ecosystems. The uncontrolled spread of an invasive species poses a serious threat to biodiversity and for the efficient functioning of local ecosystems, the occurrence of which is increasing at an alarming rate worldwide [1]. The recognition of this serious problem is highlighted in the 8 th article of the Biodiversity Convection, which is dedicated to the impact of invasive plants [2]. One of the world's most invasive plants is _Rumex confertus_. Of the potentially most invasive plant species in Europe, this plant has been categorized in the highest risk assessment, class III [2]. _R. confertus_ is native to Europe and Asia [3], and has been reported as an invasive plant to the flora in Bulgaria [4], Latvia [5], Lithuania, Romania, Serbia, Hungary, and the Czech Republic [3]. Being rhizomatous, it is able to sprout again after physical and chemical management [3], and hence is difficult to control. It grows quickly, and produces a large number of viable seeds [6]. According to the 2016 USDA report [6], the genus _Rumex_ comprises a number of species considered to be significant weeds. For example, _Rumex acetosella_, _R. conglomeratus_, _R. crispus_, and _R. obtusifolia_ are weeds found in ruderal areas, and must be removed manually for effective control. _R. crispus_ seeds are reported to be viable even after more than 80 years of vegetation in dry conditions. The plant is also toxic to poultry and causes mortality to sheep. _R. acetosella_ causes high fever and dermatitis in humans and is also toxic to sheep. In contrast, the roots of many species belonging to the _Rumex_ genus have been used in folk medicine since ancient times because of their gentle laxative effect [7]. With regard to the current study, _R. confertus_ shares many of the abovementioned harmful traits, and hence is problematic if not kept under control [6]. Given the problems associated with the physical and chemical control of _R. confertus_, it is not surprising that biological control has been considered and implemented. One such control is associated with the soil type used. For example, it has been reported that Dystric Arenosol, Entic Podzol, Brunic Arenosol, and Calcaric Leptosol soils are unfavorable for _R. confertus_ growth. It has also been found that _R. confertus_ growth can be limited by reducing the available nitrogen and phosphorus in the soil [8]. Other aspects of biological control of _R. confertus_ include the use of flowering plants or floral resources as a way to attract and retain an invasive plant's natural enemies for the protection of organic crop production. However, this approach has inconsistent outcomes given that there are few correlations between an increase in natural enemies and a reduction in plant damage [9]. According to [PERSON] (2020) [9], the effect of plant diversity on the potential use of natural enemies to regulate insect pest populations below damaging levels is complex due to the plant-pest-natural enemy interaction. Therefore, plant diversity can either impair or promote the abundance of natural enemies and their ability to regulate insect pest populations and more importantly, reduce plant damage. In nature, _R. confertus_ is inhabited by a number of herbivous insects, which while feeding will impair the plants' generative organs, with a high correlation between the plant damage index and the content of polyphenolic acids being confirmed [10]. Field and laboratory studies confirmed the potential of using _Gastroidea viridula_ Deg. (Coleoptera: Chrysomelidae) as a biological control of _R. confertus_[11]. The interaction between damaged plants and the environment occurs by means of the emission of volatile organic compounds (VOCs), which provide signals to influence neighboring plants [12].