Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC₅₀ values for B. cruckchanksii essential oil of 3.58 µL L⁻¹ air at 4 h, and for P. uviferum essential oil of 9.41 µL L⁻¹ air and 1.02 µL L⁻¹ air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.

The horn fly is an economically important hematophagous ectoparasite of cattle. Its management relies heavily on broad-spectrum pesticides, which are harmful to the environment and have led to the development of resistance. Therefore, alternative control methods are needed. Semiochemicals involved in communication between horn flies and their host are a promising alternative. Considering that the egg-laying of this fly occurs almost exclusively in fresh cattle dung, and most parts of its life cycle occur totally in dung, dung volatiles might play an important role in horn fly behavior. Therefore, the main aim of this study was to evaluate the effects of volatile blends and compounds emitted from fresh/aged cattle dung on the olfactory response and oviposition of horn flies. Dung blends were captured and analyzed by SPME-GC/MS. p-Cresol was the most abundant compound in dung blends, followed by α- and β-pinene, limonene, and β-caryophyllene, among other common dung volatiles. Fresh-dung volatiles attracted males and females in a Y-tube olfactometer, and they elicited the egg-laying of flies in two-choice tests. p-Cresol and α-pinene were attractive to females and they elicited higher oviposition, demonstrating that dung volatile semiochemicals, in part, lend to dung attractiveness and stimulate the horn fly oviposition.

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 (C₂₀), and a long-chain hydrocarbon (C₂₆). From the terminalia extracts, hentriacontane, heptacosane, and heneicosyl, heptacosyl and docosyl acetates were identified by GC-MS, and their roles are unknown in the development of short-distance sexual behaviors, but they could serve to mark a trail leading the male towards the female in the final stage of approach for courtship/mating. Thus, we proposed the hypothesis that P. chilensis females emit both a long-range and a trail-pheromone, which, if confirmed, would be a rare case in this family. The specific identity of the compounds obtained by HSD, as well as the activities of these chemicals and those obtained from the terminalias, should be evaluated in future behavioral studies, as well as regarding their potential to attract males under field conditions. The current document is the first report on volatiles obtained from aerations and compounds extracted from female terminalia in P. chilensis.

Araucaria araucana is one of the longest-living Chilean trees. Recently, Araucaria Leaf Damage disease, which causes damage to branches and crowns, was detected. Sinophloeus porteri, a bark beetle affecting A. araucana, could be associated with foliar damage. However, little is known about their ecological and chemical interactions. This study examined the olfactory response of S. porteri to volatiles emitted from A. araucana. Branches and weevils were collected from a national park, and volatiles were trapped from both healthy and unhealthy branches. Thirty terpenes were identified, some of which were reported for the first time in A. araucana. Healthy branches emitted large amounts of myrcene (>360 ng g⁻¹ day⁻¹), and unhealthy branches showed high hibaene emanations (>140 ng g⁻¹ day⁻¹). Olfactory assays verified that S. porteri was attracted to the volatile blends of branches, regardless of the health condition of the branches, but preferred the blend of unhealthy branches. Moreover, myrcene was repellent to these weevils, and hibaene acted as an attractant, suggesting that A. araucana might use myrcene for defense against S. porteri, and hibaene could stimulate host selection by beetles.

Araucaria araucana (Molina) K. Koch, an endemic conifer of Chile and Argentina, has been severely impacted in recent years by Araucaria Leaf Damage (ALD). Previous research has established that volatile organic compounds (VOCs) released by healthy (H) and leaf-damaged (LD) Araucaria araucana branches modulate the behavior of Sinophloeus porteri. Specifically, myrcene, the most abundant compound in healthy branches, acts as a repellent to this insect, whereas hibaene, found in high concentrations in leaf-damaged tissue, acts as an attractant. This study compared the chemical profiles of healthy and leaf-damaged branches across two distinct geographic areas: Nahuelbuta (PNN) and Villarrica (PNV) National Parks. Following VOC capture using Porapak Q and subsequent GC-MS analysis, 31 compounds were detected and 29 were identified. The results indicate that hibaene was consistently detected across health categories, whereas camphor was particularly abundant in leaf-damaged trees from PNV. Overall, the data suggest that tree health status is associated with marked changes in VOC profiles, although the present design does not allow constitutive and induced responses to be fully disentangled. Consequently, monitoring these volatile emissions represents a strategic tool for the early detection and mitigation of damage caused by pests and diseases in these forest ecosystems.