Behavioural and electrophysiological responses of Liothrips jatrophae (Thysanoptera: Phlaeothripidae) to conspecific extracts and some of its identified compounds

This study investigated the behavioural and electrophysiological responses of the thrips Liothrips jatrophae to conspecific extracts and some of its identified compounds. We integrated four constituents of the insect's chemical communication: identification of the compounds from L. jatrophae extract, behavioural response to extracts and synthetic blends, morphology of the main olfactory receptors (antennae), and electrophysiological response of the main olfactory receptors of the antennae to extracts and to individual synthetic compounds and synthetic blends. Analysis by GC–MS revealed that the L. jatrophae extract contains a mixture of 11 compounds (perillene, tridecane, β-acaridial, tetradecane, pentadecane, heptadecane, heptadecene, dodecyl isobutyrate, tridecyl isobutyrate, tetradecyl isobutyrate and hexadecyl isobutyrate). The major compounds were tridecane, pentadecane, tetradecyl isobutyrate and hexadecyl isobutyrate. When the thrips were exposed to the extracts, they exhibited an escape response, accompanied by other behavioural responses, such as rapid sideways movement and lifting of the abdomen and secretion of a drop at the tip of the abdomen. Morphology and distribution of the L. jatrophae antennal sensilla were examined with a scanning electron microscope (SEM). The antenna consists of a scape, pedicel and six flagella. The microphotographs showed two types of sensilla: basiconica and trichoidea. Single sensillum recording (SSR) showed that the sensilla basiconica located in segment IV of the antenna were the most sensitive to the L. jatrophae extracts and to a synthetic blend, whereas the sensilla trichoidea did not exhibit electrophysiological response.