Search Results (317)

Olfactory detection of essential oils (EOs), natural plant-derived mixtures of odorous volatile compounds, stimulates neural pathways involved in emotion, cognitive function, and memory in humans and significantly influences insect behavior (inducing attractiveness or repellency). In this study, the olfactory perception of rose (EO 1, a synthetic mixture with rose aroma), eucalyptus (EO 2), lemon (EO 3), clove (EO 4), rosemary (EO 5), and caraway (EO 6) EOs in untrained human participants was compared to the behavioral responses induced in Tenebrio molitor (adult insects) by EO exposure. Significant differences emerged in the perception of EO odor dimensions (pleasantness, intensity, and familiarity) using a Likert-type scale in untrained participants. The tested EOs elicited different behavioral responses in T. molitor insects, as assessed by repellency, escape, and choice tests. A positive correlation (r = 0.7861, p < 0.05) emerged between EO odor intensity perceived by participants and escape induction in T. molitor adults. GC–MS analysis revealed citronellol, 1,8-cineole, limonene, eugenol, α-pinene, and carvone as the most abundant volatile compounds in EO 1, EO 2, EO 3, EO 4, EO 5, and EO 6, respectively. The EO odor dimensions in participants and insect behavioral responses were also related to the in silico physicochemical/pharmacokinetic properties of the main EO components. Our results provide new insights into the chemical basis of olfactory preferences both in T. molitor adults and humans. Full article

Insects secrete volatile organic compounds (VOCs) for various reasons, such as intra- or inter-species communication, attracting mates, or repelling predators. The volatiles from indoor insect pests, e.g., phenolic secretions, can impact inhabitants in various ways, causing allergies, skin and eye irritations, etc. The Mupli beetle (Luprops tristis Fabricius, 1801) is one such nuisance pest that aggregates in great numbers in indoor spaces, especially near rubber plantations in tropical African and Asian countries. This study aimed to understand the whole-body volatilome of L. tristis, comprising the first detailed study of volatiles in this insect, particularly under aggregation and laboratory conditions. Whole-body VOCs were collected from sets of 500 and 1000 beetles at different time intervals and analysed by solvent-assisted desorption followed by gas chromatography–mass spectrometry (GC-MS). Compounds released by the Mupli beetle, such as 1-Octadecanesulphonyl chloride, Decane-1,1′-oxybis-, n-Nonadecanol-1 and n-Heptadecanol-1, are reported in the literature to be allergens that cause allergic reactions such as skin and eye irritations in humans. This understanding may indicate the possible reasons for the allergic reactions in people living in these insect-inhabited indoor spaces. We also report and describe the design and development of an economically feasible glass chamber for the dynamic headspace collection of volatiles released by these beetles. Full article

Most plant-based essential oil repellent products currently available on the market utilize a “green” approach based on the volatile properties of essential oils. In general, these essential oils contain terpenes, terpenoids, phenylpropanoids or benzenoids that can be used to either (1) eliminate a human’s scent through a process called odor masking, or (2) interfere with an insect’s ability to detect a person’s scent through interaction with both olfactory receptors and odorant binding proteins. Additionally, many of the essential oil blends that have been developed have been shown to exhibit antimicrobial and therapeutic properties. The primary drawback to using essential oil-based repellents is that their protection times vary widely, and typically last only a short period of time due to the volatile nature of the active ingredients, as well as differences in concentration and formulation among products. Encapsulation, nano-delivery systems, and rationally designed blend combinations are being proposed as potential methods to delay the release of the essential oil active ingredients, thus extending the duration of effectiveness of the repellent product. Since essential oils represent complex mixtures, there is a possibility that resistance to the repellent active ingredients could develop differently than it would for single-active agents. However, before such resistance can be assessed, the repellents must undergo extensive safety evaluations, along with standardized efficacy assessments against Environmental Protection Agency (EPA)-approved repellent products, and ultimately, field trials must be conducted in areas where the repellents will be used to prevent vector-borne diseases. In addition to conducting these evaluations, the repellents must comply with existing state and federal pesticide regulations. Full article

Botanical insecticides represent a promising alternative to synthetic chemicals for controlling stored-grain pests. However, their use is limited by formulation-related challenges that affect grain quality. This study conducted a comparative evaluation of the insecticidal effectiveness of Artemisia herba-alba crude extract and a solidified matrix formulation (Tablet-like formulation), against Sitophilus oryzae. The formulation involved embedding the extract in a cellulose–starch base. The evaluation included insect mortality, repellency behavior, oxygen consumption, and selected biochemical parameters. Chemical profiles were analyzed using gas chromatography–mass spectrometry (GC–MS). The crude extract demonstrated strong insecticidal activity, achieving 100% mortality at 10,000 ppm after 72 h. In contrast, the tablet-like formulation showed reduced mortality (33%) under the same conditions. Similar trends were observed in repellency tests, with the crude extract showing higher immediate activity (100%) compared to the tablet formulation (67.44%). Both treatments significantly decreased oxygen consumption and levels of lipase, α-amylase, and neuropeptide F. Only the crude extract affected protease and monoamine oxidase activities. GC–MS analysis revealed that, despite variations in the number and relative abundances of compounds detected, both formulations shared several major constituents. In sum, the crude extract showed superior performance in several parameters, particularly in rapid activity, while both forms exhibited comparable effects in other responses. These findings indicate that the intended application should guide formulation selection, with the crude extract is more suitable for rapid pest control, while the tablet-like formulation may be better for long-term protection and preservation of grain quality during storage. Full article

Phthonoloba viridifasciata (Lepidoptera: Geometridae) is the primary herbivorous insect of the rare and endangered plant Alsophila spinulosa. The aim of this study was to investigate the host-seeking mechanism of P. viridifasciata by screening volatile compounds from A. spinulosa for their attractant or repellent activity, so as to provide a theoretical basis for its eco-friendly control. We used the dynamic headspace adsorption to collect the volatile compounds from A. spinulosa. A combination of Gas Chromatography–Electroantennography Detection (GC-EAD), Gas Chromatography–Mass Spectrometry (GC-MS), electroantennography (EAG), and Y-olfactometer bioassays was used to screen and identify active compounds that induce responses in P. viridifasciata. Five active volatile compounds induced significant electrophysiological activity, including decane, undecane, 4-ethylbenzaldehyde, m-ethylacetophenone, and p-ethylacetophenone. All five active compounds triggered EAG responses in both sexes. Behavioral bioassays further revealed that 4-ethylbenzaldehyde (10⁻² and 10⁻⁴ mol/L) and decane (10⁻⁵ mol/L) act as female attractants. Meanwhile, males showed a behavioral preference response to 4-ethylbenzaldehyde at 10⁻² mol/L. Full article

Physiological and metabolic adaptations during pregnancy may increase susceptibility to harmful environmental chemicals. High maternal BMI that perturbs the metabolic, inflammatory, and hormonal milieus could modulate toxicant effects on pregnancy outcomes. First-trimester targeted urinary exposomes of 119 women (BMI ≥ 25 = 55; BMI < 25 = 64) from the Michigan Mother–Infant Pair cohort were profiled to assess how BMI influences urinary exposomes and related biological responses. A validated approach measured 96 chemicals and biomarkers of oxidative stress and glucocorticoids. Women in both groups reported similar lifestyles and consumer product use. Women with high BMI had lower urinary concentrations of several chemicals than women with low BMI. Phytoestrogens, polycyclic aromatic hydrocarbons, and insect repellants showed a higher magnitude of positive associations with other markers of exposure, oxidative and glucocorticoid stress in the high-BMI group, while UV filters, flame retardants, and phthalates showed a higher magnitude of positive associations with oxidative stress markers in the low-BMI group. The patterns of associations of exposure markers with stress markers and pregnancy outcomes (gestational age and birthweight) differed by maternal BMI. This highlights the importance of incorporating maternal BMI into the evaluation of exposure burden and its effects, as a factor that may actively shape biological responses. Full article

In the framework of integrated pest management, plant-based insecticides represent a promising tool for the control of insect pests. Indeed, N-alkylamides extracted from Acmella oleracea (L.) RK Jansen (Asteraceae) have been recently studied for their insecticidal properties. The encapsulation of these substances into stable formulations, like nanoemulsions (NEs), could boost their efficacy and stability. Herein, a N-alkylamide-enriched fraction (AEF) encapsulated into a stable NE was tested against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a key tomato pest, able to develop resistance towards chemical insecticides. Acmella oleracea was reported to be effective against many target species, but this is the first time that this extract was tested against T. absoluta in terms of toxicity against eggs, ingestion toxicity on larvae and repellence on adults. The AEF, containing 42.8% of spilanthol, was prepared by combining two eco-friendly techniques, namely supercritical CO₂ extraction and wiped-film short path molecular distillation, and then encapsulated into a stable NE. Preliminary tests on the phytotoxicity of the AEF-NEs at 0.25 and 0.5% (w/w) a.i., compared with a control NE solution (i.e., the AEF-free NE) and a negative control (distilled water), showed a negative effect on tomato plants at the highest concentration. On this basis, three concentrations (0.06, 0.125, and 0.25% a.i.) were evaluated against eggs (topical toxicity), larvae of 2nd instar (ingestion and topical toxicity), and adults (ovideterrence) of T. absoluta. The results showed that all adopted AEF-NE concentrations caused a significant inhibition in egg hatching (>20%). The larval survival, at the end of the evaluation (72 h), in ingestion toxicity tests were significantly different in the AEF-NEs at 0.06, 0.12, and 0.25% (56.7, 33.3 and 26.7%, respectively) compared with control NE and distilled water (100% both). Similar results were obtained in the adult emergence in ingestion toxicity comparing AEF-NEs at 0.06, 0.12, and 0.25% (64.7, 50.0 and 75.0%, respectively) with control NE and distilled water (100% both). Finally, a significant ovideterrent effect was shown by the concentrations 0.125 and 0.25% of the AEF-NEs (% of egg laid: 7.5 and 27.4% respectively), compared with distilled water. Overall, the AEF-NE tested showed promising and encouraging effectiveness as ovicidal and larvicidal against T. absoluta. This supports its potential use as an effective alternative to synthetic products for the control of this important pest. Full article

Butterflies locate host sites using plant volatiles, while larval frass cues induce avoidance. This study investigated the olfactory responses of adult Papilio polytes to nine shared plant and frass volatiles across 1 × 10³ to 1 × 10⁶ ng load doses using electroantennography (EAG) and Y-tube olfactometer assays. EAG responses were significantly influenced by chemical composition, dose, and sex, as well as all their interactions. In contrast, behavioral choices were significantly driven only by chemical composition and its interaction with dose. Although females exhibited higher peripheral sensitivity than males, this physiological sexual dimorphism did not result in significant behavioral differences. Linalool, citronellal, and geraniol were identified as the most potent elicitors. While their single forms and binary blends elicited attraction or neutrality, the ternary mixture significantly repelled both sexes. These results demonstrate that VOC blend composition determines the direction of behavioral responses, with linalool playing a pivotal role in the transition from attraction to avoidance. These findings highlight the importance of shared plant–frass VOCs in host selection by oligophagous insects and provide a foundation for manipulating P. polytes behavior. Full article

Host alternation is a common behavioral strategy among many herbivorous insects. The mulberry longhorn beetle, Apriona germari is a destructive wood-boring pest. The adults exhibit rhythmic host alternation between feeding and oviposition hosts. However, the temporal rhythm and regulatory mechanisms underlying this behavior remain unclear. In the present study, by observing the dynamics of the numbers of A. germari on mulberry (Morus alba, feeding host) and willow (Salix babylonica, oviposition host) trees in a cage, we first found that both females and males began to aggregate on mulberry trees at dawn. Following 18:00 at dusk, the number of females on mulberry declined sharply, whereas the number of males decreased slightly, with a greater proportion of males staying on mulberry. To investigate the role of host volatiles in regulating the host alternation in A. germari, we then carried out two-choice olfactory assays to test whether the behavioral responses of A. germari to the host volatiles from mulberry and willow twigs differed between 04:00 and 08:00 (dawn, aggregated on mulberry) and 18:00 to 22:00 (dusk, dispersed from mulberry). Males were consistently attracted to the volatiles from healthy mulberry at both dawn and dusk, but not to those from willow. Females showed no attraction to the volatiles from either of two hosts at dawn; however, at dusk, they were significantly attracted to willow volatiles. Furthermore, volatiles from feeding-damaged mulberry trees were repellent to both sexes, particularly to males at dawn. These results indicate that the rhythmic host alternation in A. germari is partly mediated by host volatiles and an unidentified male-produced pheromone may be present in this species. Our findings can deepen the understanding of the host alternation in longhorn beetles, and offer a theoretical foundation for developing semiochemical-based, eco-friendly strategies for controlling this pest. Full article

Invasive plant species are increasingly recognized not only as ecological threats but also as potential sources of bioactive compounds with agricultural applications. However, the combined allelopathic and insecticidal potential of Ailanthus altissima’s different plant parts remains insufficiently explored. This study evaluated the bioactivity of different plant part (leaf, bark, and branch) extracts of A. altissima. Secondary metabolites were characterized by HPLC–DAD–MS, while ethanol extracts (0.5–5%) were tested on wheat (Triticum aestivum) seed germination, seedling growth, oxidative status, and on the survival and repellency of the rice weevil (Sitophilus oryzae). Biological responses were strongly plant part and concentration-dependent. Leaf extracts contained the highest phenolic levels, dominated by caffeoylquinic acids and quercetin derivatives, whereas bark and branch extracts showed lower but compositionally distinct profiles. Despite this, bark and branch extracts produced the strongest biological effects, inhibiting germination energy and root growth at higher concentrations, while leaf extracts stimulated seedling performance, including increased vigor index, while in insect bioassays, bark and branch extracts caused higher mortality and stronger suppression of rice weevil populations. This study provides new evidence that biomass extracts of the invasive species A. altissima represent a promising source of biologically active compounds with both allelopathic and insecticidal properties, highlighting its potential valorization as a plant-based biopesticide for sustainable pest management. Full article

The use of botanical extracts derived from Jatropha spp. offers a sustainable alternative for controlling insect pests, thereby reducing reliance on synthetic chemical insecticides. A systematic review and meta-analysis were conducted to summarize the published evidence on the insecticidal activity of these extracts. Electronic database searches were conducted to identify relevant studies evaluating Jatropha spp. botanical extracts against insect pests, including mortality, antifeedant activity, time of development, oviposition inhibition, and repellency. A random-effects meta-analysis for continuous variables with 95% confidence intervals was employed to compare treated insects against a control group. The study encompassed 77 articles, which evaluated extracts from various botanical parts of Jatropha curcas and Jatropha gossypifolia against insects from nine taxonomic orders. The results of the meta-analyses demonstrated that aqueous, ethanolic, and methanolic extracts from leaves and seeds were effective in increasing the mortality rate of treated insects. These extracts also affected the insects by prolonging development time, reducing weight gain in larvae and pupae, inhibiting oviposition, and increasing the percentage of repellency. Consequently, the foliar application of botanical extracts obtained from the leaves and seeds of J. curcas and J. gossypifolia represent a sustainable and agroecological alternative for the control of insect pests from different taxonomic orders. Full article

A comprehensive ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the simultaneous quantification of 50 pesticide biomarkers across nine current-use chemical classes in human urine. These classes include organophosphorus insecticides (which encompass dialkyl phosphates and specific metabolites), pyrethroid insecticides, fungicides, neonicotinoid insecticides, herbicides, insect repellents, organochlorine pesticide metabolites, and plant growth regulators. The method employs solid-phase extraction (SPE) for sample preparation, requiring only 0.2 mL of urine. Chromatographic separation was optimized using a Hypersil Gold AQ column, achieving a total run time of 18 min. Mass spectrometric detection utilized polarity switching in electrospray ionization mode with multiple reaction monitoring. Method validation demonstrated satisfactory linearity (R² > 0.99), high sensitivity with limits of detection ranging from 0.01 to 0.88 ng/mL, and extraction efficiencies between 85% and 113%. Precision and accuracy were within acceptable ranges, with relative standard deviations generally below 15%. The method’s robustness was confirmed through participation in external quality assessment schemes. Application to real samples revealed significant inter-individual variability in pesticide biomarker concentrations, with total measured biomarker levels ranging from 89 to 1242 ng/mL across the 10 individuals analyzed. This method offers comprehensive coverage of current-use pesticide chemical classes, including 30 biomarkers from the U.S. National Health and Nutrition Examination Survey (NHANES) biomonitoring program, and demonstrates improved sensitivity and broader analyte coverage compared to existing methods. The developed assay provides a valuable tool for large-scale biomonitoring studies and environmental health research. Full article

Three-dimensional (3D) epicuticular wax coverage on plant surfaces contributes to multifunctional surface properties, such as enhanced water repellence, reduced pathogen adherence, modified optical properties, and reduced insect adhesion. The diversity in wax projection morphology, size, abundance, and spatial arrangement among plant species results in a broad spectrum of anti-adhesive effects, reflecting both phylogenetic history and ecological function. This study presents a numerical model consisting of 3D tubular-shaped structures randomly deposited on a substrate and forming a highly porous layer. The simulations based on this model demonstrate a strong reduction in adhesion to the contacting insect adhesive pad. It is found that a structure formed by sufficiently long tubes, where the length is enough to support the tubes in space and build a porous 3D structure with a very low density, at relatively weak attraction to the underlying substrate, leads to the weakest adhesion. The model is constructed on the basis of our recent works combining discrete and continuous approaches in biological modeling. It mainly exploits the technique of the movable digital automata, allowing modeling of numerous numerically elastic cylinders that can be moved in 3D space, elastically collide with one another and with boundaries, and build self-consistent surface structures, which can be used to mimic nano- or microscale surface coverages of real plants. Full article

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. Full article