## 1 Introduction  
Western flower thrips, _Franklinella occidentalis_ (Pergande) (Thysanoptera: Thripidae), first arose as one of the world's most significant invasive pests of agricultural and horti-cultural crops in the 1970s and 1980s [1]. _F. occidentalis_ was originally described in 1895 in California, USA, and has since become an economically significant destructive pest with a geographic range that has rapidly expanded over the last 20 years. _F. occidentalis_ causes direct damage through feeding and oviposition on leaves, flowers, and fruits, affecting yields and aesthetic appearance; it also causes indirect damage through the transmission of viruses [2; 3]. As a phytophagous pest, _F. occidentalis_ can attack over 250 crop species from over 60 families [4], yet its full host range is likely much broader, including vegetables, ornamentals, fruits, and cotton, among others [5]. In addition, _F. occidentalis_ occurs on many uncultivated plants [6]. _F. occidentalis_ has spread extensively through increased international trade and has become a dominant thrips species in many of the areas it has invaded [1; 7; 8]. Reliable estimates of economic losses are scarce and difficult to determine; however, given the high polyphagia of this pest as well as the plant pathogenic viruses it transmits, economic losses are likely very high [9; 10]. Therefore, great attention has been paid to the effective control of this pest species. For the control of _F. occidentalis_, reliance on a single management tactic, especially insecticides, has not been effective or sustainable [5; 11]. Despite integrated pest management strategies being implemented, insecticides remain the cornerstone of many _F. occidentalis_ management programs [5; 12]. Such reliance on insecticides is unfortunate because _F. occidentalis_ populations have a propensity for developing insecticide resistance, and resistance to several insecticide groups has been reported, including organophosphate, pyrethroid, and organochlorine pesticides [13; 14; 15; 16]. Thus, novel strategies as alternatives to conventional insecticides for managing _F. occidentalis_ are urgently needed. In recent years, ethological control strategies have been considered more sustainable and environmentally friendly for pest management. However, most ethological control studies using semiochemicals have focused on larger insect pests, such as moths and beetles, with fewer studies on the numerous smaller insect pests, such as thrips [11; 17]. Since the middle of the last century, the use of semiochemicals for pest control as a replacement for insecticides has been studied as a sustainable alternative [18]. Therefore, studies on thrips-host plant interactions are necessary for determining effective volatile organic compounds (VOCs) to implement practical _F. occidentalis_ control methods [18]. Functional VOCs act as semiochemicals, which determine and/or modify the behavior of insects, through attraction or repulsion; in some cases, they are toxic to certain insect species [19; 20]. _Houttupnia cordata_ Thumb. (Piperales: Saururaceae), commonly known as fish mint, is a creeping aromatic medicinal herb with thin spreading rhizomes and a height of 30-60 cm [21]. It is an important traditional medicine in East and Southeast Asia, especially in China, Japan, and Thailand, where the plant is known as Kao-Tong or Plu Kao [22]. _H. cordata_ can be commonly found in the wild and in cultivated fields in Guizhou Province, China; their fresh leaves and rhizomes are consumed as a vegetable, conditions, and spices. In particular, few phytophagous insects have been detected on this plant species, which may relate to the plant's specific odor [22; 23] that repels insects or is not preferred by them. Therefore, in the present study, the behavioral and electrophysiological responses of _F. occidentalis_ to the volatiles of fresh _H. cordata_ leaves were investigated. Further, behavioral responses of _Orius similis_ Zheng (Hemiptera: Anthocoridae), an important natural enemy of _F.