The effect of the sterile insect technique on vibrational communication: the case of Bagrada hilaris (Hemiptera: Pentatomidae)

The painted bug, Bagrada hilaris, is an agricultural pest in its original areas (Africa, South Asia, and the Middle East), and it has recently been recorded as an invasive species in southwestern part of the US, Chile, Mexico, and two islands in the Mediterranean basin. Its polyphagous diet causes severe damage to economically important crops. The control of this pest is primarily achieved by means of synthetic pesticides, which are often expensive, ineffective, and harmful to the ecosystem. Recent physiological bioassays to assess its potential control through the sterile insect technique demonstrated that mating between untreated females and males irradiated at doses of 64 and 100 Gy, respectively, resulted in 90% and 100% sterility of the eggs produced by the females. In this study, the mating abilities of virgin males irradiated at 60 and 100 Gy with virgin females were measured through a study of short-range courtship mediated by vibrational communication. The results indicate that males irradiated at 100 Gy emit signals with lower peak frequencies, mate significantly less than unirradiated males do, and do not surpass the early stages of courtship. Conversely, males irradiated at 60 Gy present vibrational signal frequencies that are comparable to those of the control and successfully mated males. Our findings suggest that B. hilaris individuals irradiated at 60 Gy are good candidates for the control of this species, given that they retain sexual competitiveness regardless of their sterility, through an area-wide program that incorporates the sterile insect technique

Behavioural responses of the egg parasitoid Trissolcus mitsukurii to the footprints of Halyomorpha halys and Nezara viridula

Trissolcus mitsukurii is Asian egg parasitoids associated to different pentatomids such as Halyomorpha halys. Adventive populations of T. mitsukurii were found in Northern Italy showing a great impact on this pest, suggesting its exploitation as a biological control agent (BCA) against H. halys. Releasing an exotic parasitoid requires investigating the interaction BCA/environment, to avoid negative impacts on the entomofauna of the new habitat. Trissolcus mitsukurii is mainly associated to Nezara viridula in its native area, hence, we investigated the female parasitoid’s ability to distinguish between naturally released cues of H. halys and N. viridula and compared it with the foraging behaviour of Trissolcus japonicus. A single female parasitoid was exposed to contact kairomones of both pests, to evaluate its modifications in orthokinetic and locomotory behaviour. Additionally, for T. mitsukurii, synthetic compounds simulating the cues of the two pentatomids were used. The results confirmed the preference of T. japonicus for H. halys while T. mitsukurii preferred N. viridula’s cues. The significance and consequences of these results in the biological control of H. halys in invaded areas are discusse