Stink Bug Communication and Signal Detection in a Plant Environment.

Abstract

Simple SummaryPlant-dwelling stink bugs communicate with chemical and plant-borne vibratory signals that are altered when transmitted through the substrate and air. Mates are attracted to the same plant by pheromones, where they exchange information through mechanical and close-range chemical signals. Plants absorb odor molecules from insects and produce kairomones that can enhance or reduce insect responses to pheromones. Long-range communication between stink bug mates in the field occurs exclusively via pheromones. The species specificity of the sex-pheromones guarantees their success in finding mates in the plant environment. Substrate-borne communication occurs in a narrow frequency range that is tuned to the mechanical properties of the plant. Vibratory signals are transmitted with low attenuation and with altered frequency, amplitude, and temporal characteristics. The frequency sensitivity of the subgenual organ is tuned to the low-frequency resonant properties of the plants. Recognition is encoded in the vibratory signal species- and sex-specific temporal parameters and directionality in the time delay between signals arriving from different directions. The characteristics of behaviorally described multimodal close-range communication on a plant are under-investigated. Studies of neuronal processing of multimodal sensory signals in the stink bug brain are needed to understand how their integration affects behavioral responses. Plants influenced the evolution of plant-dwelling stink bugs’ systems underlying communication with chemical and substrate-borne vibratory signals. Plant volatiles provides cues that increase attractiveness or interfere with the probability of finding a mate in the field. Mechanical properties of herbaceous hosts and associated plants alter the frequency, amplitude, and temporal characteristics of stink bug species and sex-specific vibratory signals. The specificity of pheromone odor tuning has evolved through highly specific odorant receptors located within the receptor membrane. The narrow-band low-frequency characteristics of the signals produced by abdomen vibration and the frequency tuning of the highly sensitive subgenual organ vibration receptors match with filtering properties of the plants enabling optimized communication. A range of less sensitive mechanoreceptors, tuned to lower vibration frequencies, detect signals produced by other mechanisms used at less species-specific levels of communication in a plant environment. Whereas the encoding of frequency-intensity and temporal parameters of stink bug vibratory signals is relatively well investigated at low levels of processing in the ventral nerve cord, processing of this information and its integration with other modalities at higher neuronal levels still needs research attention.