Factors to Male-Female Sex Approaches and the Identification of Volatiles and Compounds from the Terminalia of Proholopterus chilensis Forests in Chile

Proholopterus chilensis (Cerambycidae: Cerambycinae) is a native species and an important damage agent in the Nothofagaceae forests of southern Chile, significantly affecting timber production in some areas, especially production of Nothofagus obliqua , with no sanitary management measures currently available. Therefore, the present research determined the predisposing factors for male–female sex approaches and identified, for the first time, some compounds that appear to mediate sexual behaviors that could be used to develop specific, safe, and effective control strategies. Interestingly, the chemical communication for mating purposes in P. chilensis preliminarily seems to include both possible “volatile or airborne” pheromones (eventually long-range ones) and short-range pheromonal compounds produced only by females, something, as far as we know, unique in Cerambycinae. During the spring–summer seasons between 2019 and 2023, in the localities of Maquehue (La Araucanía Region) and Llifén (Los Ríos Region), we collected 262 virgin Proholopterus chilensis (1 female/2.3 males) specimens emerging from the live trunks of N. obliqua trees, an atypical sex ratio in Cerambycidae, suggesting high male competition for females. Virgin specimens of both sexes were individually placed in panel traps in the field, capturing only males (n = 184) over the field study seasons and only in traps baited with females. This fact preliminarily suggests the P. chilensis females emit possible “volatile or airborne” pheromones (eventually being a long-range sex pheromone), something unusual in Cerambycinae, the subfamily to which it currently belongs, although the taxonomic status of the species is under debate. In Llifén and Santiago (Metropolitan Region), behavioral observations were conducted, which allowed us to define the conditions necessary for male–female encounters that were replicated when carrying out volatile captures (Head Space Dynamic = HSD) and collections of compounds from terminalias excised from females. In field trials, virgin females less than ten days old were more attractive than older ones and attracted males during the night, i.e., between 23:00 and 5:00 AM, when the ambient temperature exceeded 11.6 °C. The aeration of females under the conditions described above and subsequent analysis of extracts by GC-MS allowed the identification of compounds absent in males and the control, including two oxygenated sesquiterpenes, a nitrogenous compound (C[sub.20] ),