The role of substrate-borne vibrational signals in the sexual communication of the painted bug, Bagrada hilaris

The invasive alien stink bug Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae), native to eastern-southern Africa and central-southern Asia, poses significant economic threats to agroecosystems due to its polyphagous diet with a preference for brassicaceous crops. Current control methods using broad-spectrum insecticides are expensive and often result in significant negative ecological impacts, as well as posing a health risk to consumers. This study provides a detailed description of the mating behavior of B. hilaris, with the aim to ascertain whether substrate-borne vibrations have a role in premating phases. Such knowledge may contribute to the development of alternative biorational control techniques employing vibrational strategies. Virgin adults were tested individually or in pairs on different substrates, that is, a loudspeaker membrane and a bean plant. Vibrations emitted by males and females were recorded using a laser Doppler vibrometer, and the following spectral and temporal parameters were analyzed: fundamental frequency, emission time, repetition time, and signal modulation. Three distinct types of vibration emitted by males and females were identified: a male vibrotype (MV-1), a female vibrotype (FV), and a copula signal exclusively emitted by males (MS-2). MV-1 and FV were emitted prior to genitalia contact, whereas MS-2 was emitted within the mounting and engagement phases. Statistical analysis revealed significant transitions in behavioral phases for couples that achieved mating. By analyzing the walking behavior, there was an inverse relationship between motility and signal emission when comparing the two sexes, which suggests that males might engage in a form of searching behavior. These findings provide insight into the crucial role of vibrational communication to achieve mating in B. hilaris.