# Chinese Cabbage Changes Its Release of Volatiles to Defend against _Spodoptera litura_
###### Abstract  
Biological control is an important direction for pest control in the future, and chemical ecology is an indispensable part of biological control. Therefore, we tested the selection of _Spodoptera litura_ and parasitic wasps on the volatiles of different treatments of cabbage and collected and analyzed the volatiles of different treatments of cabbage. This study found that cabbage was fed by _Spodoptera litura_ to produce volatiles to avoid _Spodoptera litura_ while also attracting _Microphitis similis_. As a result, some compounds were found to be related to the behavior of _Spodoptera litura_ and _Microphitis similis_. These results provide a theoretical basis for searching for biological control resources and chemical control. Clinical Control, 2022 13 73 130100  
can be used to communicate with neighboring plants and insects, and they are also the precursors of plant defense measures. Over a long period of coevolution, plants and insects have developed strategies to avoid each other's defense systems [4; 5]. In response to attack by herbivorous insects, plants activate inducible defenses. Many of these inducible defenses directly target the herbivore's physiology and may protect the plant against further damage [6]. The induced insect resistance of plants is usually defined as direct or indirect according to the mode of action [7; 8; 9]. Direct modes of action involve the production of chemicals by the plant that directly harms the herbivore, whereas the indirect modes of action increase herbivore mortality through the recruitment of natural enemies [10; 11; 12]. Natural enemies of herbivores use HIPVs to locate their prey [13; 14; 15; 16]. When acting as direct defenses, HIPVs can act as repellants or can reduce larval growth [17]. For example, maize leaves initially infested by _Spodoptera exigua_ larvae can repel _S. exigua_ and thereby reduce further damage [18]. When laying eggs, _Spodoptera frugiperda_ females avoid tobacco plants that have been harmed by _S. frugiperda_[19]. HIPVs, however, can have different effects on different insects. For example, _S. frugiperda_ larvae prefer to feed on maize leaves that have been infested by _S. frugiperda_ larvae [20]. Regarding indirect defenses involving HIPVs, two natural enemies of the thrips _Thrips tabaci_, _Amblayseius cucumeris_, and _Orius similis_ use volatiles released by thrips-damaged hosts to locate their prey [21]. The parasitoid _Aphidius gifiensis_, a natural enemy of _Sitobion avenue_, is more attracted to _S. avenue_-infested wheat than to non-infested wheat [22]. Similarly, the parasitoid _Cardiochiles nigriceps_, a natural enemy of _Heliothis virescens_ but not of _Helioverpa zea_, uses plant volatiles to distinguish between _H. virescens_- and _H. zea_-infested plants [23]. Furthermore, intermittent exposure to the volatiles emitted from artificially damaged _Arabidopsis_ has been shown to induce defensive responses in undamaged neighboring plants [24]. The current research concerns the effects of HIPVs on _S. litura_ and _M. similis. S. litura_ is a serious pest, i.e., its larvae consume the leaves of tobacco and many other valuable crop plants. Although HIPVs are known to increase the attractiveness of sex pheromone lures used to trap _S. litura_ adults, little is known about the effects of HIPVs on the feeding behavior of _S. litura_ larvae [25]. The larvae of _S. litura_ are hosts for the parasitoid wasp _M. similis_, which is an important biological control agent of the herbivore. _M. similis_ can reduce the weight gain and feed intake of the _S. litura_ larvae and can increase larval mortality [26; 27]. In addition, _M. similis_ is a vector of insect asoviruses-vesicle virus. The \"bee-venom\" coordinated control mode can expand the spread radius of the virus in the host population, thereby greatly improving the spread of _M. similis_ biological control effect [28]. In the current research, we assessed the responses of _S. litura_ and _M.