Chemical control of the maize weevil (Sitophilus zeamais) has been ineffective and presents serious collateral damage. Among plant-derived insecticides, essential oils (EOs) are suitable candidates to control this stored products pest. In this work, the insecticidal activities of 45 natural EOs against S. zeamais adults were screened, and the most promising ones (24 EOs) were characterized by GC–MS. The repellent and toxic effects (contact and fumigant) of these 24 EOs were determined, and by a cluster analysis they were classified into two groups considering its fumigant activity and contact toxicity. For the EOs with the highest fumigant potential (14 oils) and their main active constituents (17 compounds), lethal concentrations were determined. The most active EOs were those obtained from L. stoechas and L. alba, with LC₅₀ values of 303.4 and 254.1 µL/L air and characterized by a high content of monoterpenes. Regarding the major compounds, the oxygenated monoterpenes R-(+)-pulegone (LC₅₀ = 0.580 mg/L air), S-(-)-pulegone (LC₅₀ = 0.971 mg/L air) and R-(-)-carvone (LC₅₀ = 1.423 mg/L air) were the most active, as few variations in their concentrations significantly increased insect mortality.

The maize weevil (Sitophilus zeamais) is one of the main insect responsible of significant losses in stored products, and to keep nutritional value of them to find effective and safe solutions are very important. The Hypericum genus might be a potential source of new bio-insecticides due to the chemical composition of essential oils. In this study, components of essential oils of three Hypericum species were investigated for first time by Gas Chromatography-Mass Spectrometry (GC-MS) and, fumigant and contact toxicities as well as the repellent activity of essential oils of them were evaluated against S. zeamais adults. While the main components in H. mexicanum oil were determined as n-nonane (53.08%) and α-pinene (25.28%), the major constituents were determined as α-pinene (45.52%) and β-caryophyllene (13.59%) in the essential oil of H. myricariifolium. Chemical composition of essential oil of H. juniperinum were found to be n-nonane (12.0%), α-pinene (8.25%), geranyl acetate (7.93%), and β-caryophyllene (13.60%). The results revealed that H. mexicanum and H. myricariifolium oils have fumigant toxicity (LC50 < 500 µL/L air) and a potential action as repellents (RP > 70% at 6.2–22.7 μL/L air) for the control of the pest.

Strategus aloeus (Coleoptera: Scarabaeidae: Dynastinae) represents a significant pest of young oil palm crops in Latin America. Although a pheromone had already been identified, its use as a tool for integrated management remained limited. Thus, to elucidate the fuller characterization of the chemical signaling associated with this beetle and its host, the volatile organic compounds (VOCs) released by S. aloeus and the oil palm bulb (Elaeis guineensis) were isolated, identified, and evaluated. The analysis was conducted using gas chromatography coupled with mass spectrometry (GC—MS), and the attractant potential of the compounds was validated by testing their effects on insects’ behavior under laboratory and field conditions. From solvent-assisted extraction (SAE) samples, the compounds 2,4,7,9-tetramethyl-5-decyne-4,7-diol, sec-butyl acetate, and ethyl 4-methyloctanoate in a ratio of 58:34:8 were identified as part of a possible male-specific pheromone. Furthermore, 2-butanone and 3-pentanone were identified as components of the oil palm kairomone using static headspace with solid phase microextraction (HS-SPME) sampling. The laboratory behavioral response of S. aloeus to the 3 male-specific compounds, alone or combined, demonstrated a significant attraction (P < 0.01) of both sexes, indicating their potential involvement in intraspecific interactions, specifically as an aggregation sex pheromone. In field trials, mixtures of 3 to 5 semiochemicals demonstrated high capture rates with a female-biased proportion (80:20). The treatment containing 2-butanone, 3-pentanone, and sec-butyl acetate exhibited the highest efficacy (P < 0.0001).

Behavior modification using chemical stimuli is a promising tactic for integrated management of lepidopteran pests. Therefore, this approach was evaluated for the management of the butterfly Opsiphanes cassina Felder 1862, a defoliating pest in oil palm plantations. To achieve this aim, we observed adults’ sexual behavior under laboratory conditions and identified glandular structures in the abdomen and hind wings of males that are associated with the production of sexual pheromones in taxonomically related insects. It was also determined that male calls to females occur at 18:00 h when they fill their glandular structures, tremble, and make abdominal movements while possibly releasing pheromones. The hairpencils of the hind wings are also exposed during this time. Furthermore, the analysis using Gas Chromatography-Mass Spectrometry (GC–MS) on the samples obtained by Solvent Assisted Extraction (SAE) revealed the identification of three male-specific volatile organic compounds (VOCs), including (E)-nerolidol, vanillin, and (Z)-7-heptadecene. The Electroantennographic (EAG) evaluation demonstrated that females respond to the compounds, indicating their likely involvement in intraspecific interactions of the species. However, the behavioral evaluation did not confirm their attractive effect under the conditions employed. Nevertheless, the identified male-specific semiochemicals could be an alternative for inclusion in integrated pest management (IPM) of this pest in oil palm crops. Therefore, it is recommended to evaluate them under field conditions.