Quantitative structure–activity relationships of monoterpenoid binding activities to the housefly GABA receptor

BACKGROUND: Monoterpenoids are a large group of plant secondary metabolites. Many of these naturally occurring compounds have shown good insecticidal potency on pest insects. Previous studies in this laboratory have indicated that some monoterpenoids have positive modulatory effects on insect GABA receptors. In this study, the key properties of monoterpenoids involved in monoterpenoid binding activity at the housefly GABA receptor were determined by developing quantitative structure-activity relationship (QSAR) models, and the relationship between the toxicities of these monoterpenoids and their GABA receptor binding activities was evaluated. RESULTS: Two QSAR models were determined for nine monoterpenoids showing significant effects on [3H]-TBOB binding and for nine p-menthane analogs with at least one oxygen atom attached to the ring. The Mulliken charges on certain carbon atoms, the log P value and the total energy showed significant relationships with binding activities to the housefly GABA receptor in these two QSAR models. CONCLUSIONS: From the QSAR models, some chemical and structural parameters, including the electronic properties, hydrophobicity and stability of monoterpenoid molecules, were suggested to be strongly involved in binding activities to the housefly GABA receptor. These findings will help to understand the mode of action of these natural insecticides, and provide guidance to predict more monoterpenoid insecticides. Copyright © 2012 Society of Chemical Industr

Plant-derived compounds: acute toxicity, synergism, and effects on insect enzyme activity and flight motor responses.

Botanical extracts may contain compounds that have insecticidal properties that may be developed as inexpensive insecticides. In this thesis, I used a series of techniques to identify the acute toxicities and modes of action of plant-derived compounds against the Yellow Fever mosquito Aedes aegypti and the blowfly Phaenicia sericata. Initially I evaluated the acute toxicity of 16 phytochemicals on aquatic and terrestrial insects alone or with the synergist piperonyl butoxide (PBO) to quantify their lethal and sublethal effects. From this study 5 compounds, thymol, eugenol, pulegone, α-terpineol and citronellal, were selected for further study. I then evaluated the biochemical mechanisms underlying the activity of these phytochemicals and the basis of their increased toxicity in the presence of PBO. These phytochemicals affected the biotransformational capacity of these insects to detoxify the compounds, and their effects were enhanced by PBO. I then developed an electrophysiological system to evaluate the physiological effects of the plant-derived compounds and several commercially available insecticides on flight muscle impulses and wing beat signals of the blowfly, P. sericata. These compounds readily penetrate the insect cuticle and interfere with flight muscle and/or central nervous system function. All 5 compounds depressed flight-associated responses, and acted similarly to compounds that block sodium channels and facilitate Ɣ-amino butyric acid (GABA) action. I compared these responses to those induced by several synthetic insecticides whose mode of action is well known to allow us to make a more precise prediction of how the 5 compounds affect the target insects. I then evaluated the effect of the 5 phytochemicals, and octopamine on the octopaminergic system of insects by comparing the production of a second messenger molecule, cAMP, after treatment. Some monoterpenoids interfere with the octopaminergic system by targeting the octopamine receptors. The acute toxicity observed in Ae. aegypti and P. sericata may be the collective result of these compounds on complex biological systems in the insect and may depend on their structure, concentration, or exposure time. The overall results indicate that plant-derived compounds directly and indirectly affect aspects of insect physiology and could possibly be developed as new insecticides

Toxicities of thymol, citronellal, eugenol and rosemary oil to control Agriotes obscurus (Coleoptera: Elateridae) in laboratory and greehouse bioassays

Toxicities were determined for four naturally occurring monoterpenoid essential oils on late instar larvae of Agriotes obscurus in laboratory and greenhouse bioassays. Both contact and fumigant toxicities were determined for thymol, citronellal, eugenol and rosemary oil. Thymol had the greatest contact toxicity (LD₅₀=196.0 μg/larva) while citronellal and eugenol were significantly less toxic (LD₅=404.9 μg/larva and 516.5 μg/larva, respectively). Rosemary oil did not show any significant contact toxicity, at the highest dose tested, 1600 μg/larva. In fumigant bioassays, citronellal was the most toxic to wireworm larvae (LD₅=6.3 μg/cm ) followed by rosemary oil (LD₅=15.7 μg/cm ), thymol (LD₅=16.9 μg/cm³), and eugenol (LD₅=20.8 μg/cm³). Phytotoxicities were also evaluated based on corn seed germination and seedling development. In laboratory bioassays, thymol and citronellal significantly inhibited seed germination and development while rosemary oil had only minimal phytotoxic effects. Based on these laboratory results, four treatments were selected for repellency trials under greenhouse conditions. Citronellal (800 pg/seed), thymol (400 μg/seed), rosemary oil (1600 μg/seed) and eugenol (1600 pg/seed) were evaluated for their ability to protect corn seeds from Agriotes obscurus feeding damage. In the bioassay, wireworm health, seed germination, seed damage, and seedling height were evaluated. Rosemary oil treated seeds produced the highest number of distressed wireworms (56%, Odds Ratio = 2.64) compared to all other treatments while not creating any phytotoxic effects. Seeds treated with thymol were the least damaged (90.7% undamaged, Odds Ratio = 0.153) compared to the control while thymol and citronellal retarded seedling height compared to the control. Eugenol produced the lowest seed germination (25.3% germination) while citronellal, rosemary oil and thymol had no negative impact on seed germination.Land and Food Systems, Faculty ofGraduat

Factors influencing healthy menopause among immigrant women: a scoping review

Background: Many factors influence the menopausal transition and the complexity of this transition increases with the addition of immigration transition. This review aims to identify the factors that influence the menopausal transition for immigrant women based on ecosocial theory. Methods: A scoping review of English publications was conducted according to PRISMA guidelines using CINAHL, AgeLine, MEDLINE, PsycINFO, ERIC, Nursing and Allied Health Database, PsycARTICLES, Sociology Database, and Education Research Complete. Thirty-seven papers were included for this review. Results: The factors which influence the menopausal transition for immigrant women were grouped into three categories: (a) personal factors, (b) familial factors, and (c) community and societal factors. Personal factors include income and employment, physical and psychological health, perceptions of menopause, and acculturation. Familial factors include partner support, relationships with children, and balancing family, work, and personal duties. Community and societal factors encompassed social network, social support, healthcare services, traditional cultural expectations, and discrimination in host countries. Conclusions: Interventions addressing the menopausal transition for immigrant women should be designed considering different psychosocial factors and actively work to address systemic barriers that negatively impact their transition.Medicine, Faculty ofNon UBCReviewedFacult

Fly emergence from manure of Japanese quail fed thymolor isoeugenol-supplemented diets

Many problems in poultry production are caused by a combination of interrelated factors such as management, stress, nutrition and exposure to pathogens. Saprophagous flies that develop in poultry manure are a potential route of pathogen transmission. Besides their nuisance, defecation and regurgitation of flies soils equipment and structures and can reduce light levels of lighting fixtures. These effects clearly affect management and may contribute to reductions in poultry egg production, health and welfare. Many essential oils or their main components have bioactive effects such as natural repellents and insecticides, antioxidants, anticholesterolemics, and antimicrobials. This study evaluated if supplementing quail feed with thymol or isoeugenol as functional food could alter the production of flies from manure. Dropping samples deposited by quail fed with a supplementation of 2000 mg thymol or isoeugenol per kg of feed or no supplement (control) were collected. Each sample was incubated inside an emergence cage that was inspected daily to collect emerging adult flies. Fewer flies emerged from droppings of quail fed a thymol supplemented diet (P = 0.01) and tended to a lower emergence from droppings of isoeugenol fed quail (P = 0.09). The number of positive containers for Musca domestica was smaller from quail droppings of thymol (P = 0.02) or isoeugenol (P = 0.01) supplemented feed than from their control counterparts, suggesting an oviposition repellent effect. Supplementing quail feed with thymol or isoeugenol has an overall moderate effect against flies, reducing M. domestica emergence.Fil: Lynch Ianello, I.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinar de Biología Vegetal (p). Grupo Vinculado Centro de Relevamiento y Evaluacion de Recursos Agricolas y Naturales; ArgentinaFil: Battan Horenstein, Moira. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; ArgentinaFil: Labaque, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Luna, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Gleiser, Raquel M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinar de Biología Vegetal (p). Grupo Vinculado Centro de Relevamiento y Evaluacion de Recursos Agricolas y Naturales; Argentin