Composition, Repellent, and Insecticidal Activities of Two South American Plants against the Stored Grain Pests Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae)

As part of a screening program to evaluate the biological activity of indigenous plants, we report the composition and the bioactivity of essential oils (EOs) extracted from Te de Burro ´ Aloysia polystachya [(Griseb.) Moldenke] and Lemon VerbenaAloysia citriodora [Palau] against two of the most widespread secondary pests of stored products, the red flour beetle Tribolium castaneum [Herbst] and the confused flour beetle Tribolium confusum [Jacqueline du Val]. Analysis by gas chromatography-mass spectrometry of the EOs led the identification of their major constituents and their relative proportions. EO ofA. citriodorashowed the highest repellent activity against both beetles (>70%). On the other hand, both plants showed fumigant toxicity only against T. confusum, without significant differences between them (LC50 values of 5.92 and 5.53 mg/L air forA. polystachya andA. citriodora, resp.). For contact toxicity (topical applications) the EO ofA. polystachyawas more effective (LD50 = 7.35ug/insect) than the EO ofA. citriodora (LD50 = 13.8g/insect) only against T. castaneum. On the other hand, T. confusum was not susceptible by contact to any of these EOs. These results provide important tools for the development of an Integrated Pest Management (IPM) program.Fil: Benzi, Verónica Soledad. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stefanazzi, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; ArgentinaFil: Murray, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Werdin Gonzalez, Jorge Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ferrero, Adriana Alicia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; Argentin

Bioactividad de aceites esenciales de hojas y frutos del aguaribay (Schinus molle L.) en el gorgojo del arroz (Sitophilus oryzae L.)

Rice weevil (Sitophilus oryzae L.) is a primary insect pest of stored grain. The development of resistance resulted in the application of synthetic insecticides. In recent years many plant essential oils have provided potential alternatives to currently used insect control agents. The Brazilian pepper tree (Schinus molle L. var. areira (L.) DC.)(Anacardiaceae) has different biological properties such as insecticidal activity. In this study, repellent, fumigant activity, nutritional indices, and feeding deterrent action were evaluated on S. oryzae adults. Filter paper impregnation was used to test fumigant toxicity, whereas treated whole wheat was used to evaluate repellent activity and a flour disk bioassay was done to evaluate feeding deterrent action and nutritional index alteration. Leaf essential oils showed repellent effects at both concentrations (0.04 and 0.4% w/w), while fruit essential oils lacked repellent activity. Both plant oils altered nutritional indices. Fruit essential oils had a strong feeding deterrent action (62%) while leaves had a slight effect (40.6%). With respect to fumigant activity, neither of the essential oils was found to be toxic.Fil: Benzi, Verónica Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Stefanazzi, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Ferrero, Adriana Alicia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin

Insecticidal and Insect-repellent Activities of Essential Oils from Verbenaceae and Anacardiaceae Against Rhizopertha dominica

Essential oils extracted from leaves of Aloysia polystachya and A. citriodora (Verbenaceae) and from leaves and fruits of Schinus molle var. areira (Anacardiaceae) were tested for their repellent and toxic activities against adults of Rhizopertha dominica (Coleoptera: Bostrichidae). Topical application and filter paper assays were employed for contact toxicity studies; filter paper impregnation was also used for fumigant and repellent assays. In topical tests A. polystachya was as effective as S. molle leaves. In the case of repellent assays, A. citriodora was the most effective oil based on the class scale. A.polystachya was the most toxic plant on contact toxicity by filter paper assay (LC50 26.6 mg/cm2). Fumigant toxicity was only evaluated with fruits and leaves of S. molle, and no significant differences were found between them. Published data are included to compare the fumigant toxicity of S. molle with that of A. citridora and A. polystachya.Fil: Benzi, Verónica Soledad. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Murray, Ana Paula. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ferrero, Adriana Alicia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin

Fumigant activity of essential oils of Schinus molle (Anacardiaceae) and Tagetes terniflora (Asteraceae) against adults of Pediculus humanus capitis (Insecta; Anoplura; Pediculidae)

Los aceites esenciales de hojas se aislaron por hidrodestilación. Los bioensayos se realizaron a 28 ± 2 ºC, 65% ± 5 H.R y en oscuridad. Se utilizaron cajas de Petri de vidrio (5cm de diámetro), en sus bases se colocaron 50 µL de los aceites puros. La caja se cubrió con una tapa plástica perforada que posee un tejido de hilo. Sobre este se liberaron 10 insectos protegidos por una segunda caja con diámetro equivalente. El conjunto de cajas se cerró con cinta adhesiva. Se realizaron tres réplicas por tratamiento. Como control se utilizaron cajas sin aceites. El porcentaje de volteo se evaluó cada 5 minutos durante una hora. Se calculó el TV50 por un análisis Probit. El TV50 fue 12,75 min para el aceite de Schinus molle y para el de Tagetes terniflora de 23,44 min. Ambos aceites podrían ser utilizados para el control de Pediculus humanus capitis.Dried leaves of each species were hydrodistilled. The bioassays were performed at 28 ± 2 ºC, 65% ± 5 RH and in darkness. Each experimental unit consisted of a glass Petri dish (5cm diameter) containing 50 µL of the essentials oils on a micro coverglass. Then, it was covered with a lid with a fine wire sieve attached over the central hole. Batches of 10 adults were placed over the sieve. Each unit was then covered with another Petri dish. Control units were the same but without addition of any substance. All treatmentes wre replicated three times. The percentage of knockdown was evaluated every 5 min for one hour. The KT50 value was calculated by probit analysis. The results showed that the KT50 for Schinus molle was 12.75 min and for Tagetes terniflora was 23.44. Both essential oils could be considered for the control of Pediculus humanus capitis.Fil: Gutierrez, María M.. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; ArgentinaFil: Stefanazzi, Natalia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Werdin Gonzalez, Jorge Omar. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Benzi, Verónica Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; ArgentinaFil: Ferrero, Adriana Alicia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados II; Argentin