Trissolcus mitsukurii and Trissolcus japonicus are two Asian egg parasitoids associated with different pentatomids such as Halyomorpha halys. Adventive populations of T. mitsukurii were found in Northern Italy, suggesting its employment as a biological control agent (BCA) against H. halys. Nevertheless, to reduce the latter’s population, T. japonicus was released in Italy. Releasing an exotic parasitoid requires investigating the interaction between the BCA and the environment to avoid negative impacts on the entomofauna of the new habitat. Trissolcus mitsukurii is mainly associated with Nezara viridula in its native area. Therefore, we investigated and compared the ability of female T. mitsukurii and T. japonicus to distinguish between naturally released cues of H. halys and N. viridula. A single parasitoid was exposed to contact kairomones of both pests to evaluate its modifications in orthokinetic and locomotory behaviour. The behaviour of female T. mitsukurii was also tested on synthetic compounds simulating the cues of the two pentatomids. When naturally released cues were used, T. japonicus preferred the traces of H. halys, while T. mitsukurii preferred N. viridula’s cues. Moreover, the attraction of T. mitsukurii to N. viridula’s cues was confirmed with synthetic cues. Additional studies are needed to judge if this parasitoid can be used as a BCA.

Neurotoxic insecticides are recognized and classified by their primary mode of action, but they frequently exhibit secondary targets and downstream consequences that are often neglected. Hazards to arthropod physiology and behavior can sublethally occur through environmentally relevant pesticide residues and/or by contact with non-targeted developmental stages. Drosophila suzukii is a key invasive pest of soft-skinned fruits and provides a suitable model to study how neurotoxicants interfere with olfactory-mediated orientation, a key process underlying host detection and oviposition. However, information on how neurotoxic insecticides influence olfactory-driven orientation behavior in this pest remains undocumented. This study investigated the sublethal effects of neurotoxic insecticides (chlorpyrifos, cyazypyr (cyantraniliprole), lambda-cyhalothrin and spinosad) at realistic occurrence ranges (i.e., estimated lethal concentrations 10%, LC₁₀) on adult female orientation. Contamination occurred either by residual contact at the adult stage or ingestion during larval development. Behavioral responses were assessed using a Y-tube olfactometer, while electroantennography (EAG) and quantitative expression of nine olfactory receptor (Or) genes evaluated peripheral sensorial capacity. Under adult residual contact exposure, chlorpyrifos and spinosad disrupted olfactory orientation in adult flies. In addition, these insecticides, together with lambda-cyhalothrin, increased decision-making time. Residual exposure reduced antennal sensitivity and downregulated Or gene expression. In contrast, following larval ingestion, all tested insecticides induced adult behavior disorientation without detectable effects on peripheral olfactory function. Overall, these findings highlight the importance of considering multiple exposure pathways and sublethal neurotoxic effects when evaluating insecticide hazards on targeted insects, with implications for D. suzukii ecology and the efficacy of olfactory-based integrated pest management strategies.