Jaime E. Araya

RESPUESTA DE LA POLILLA DEL TOMATE, Tuta absoluta (Meyrick), A INSECTICIDAS EN ARICA

Se comparo la susceptibilidad larvaria de la polilla del tomate, Tuta absoluta (Meyrick), colectada en tomate (Lycopersicon esculentun Mill.) en Azapa, Arica (18o 31? lat. Sur, 70o 11? long. Oeste), mediante pruebas de toxicologia con varias dosis de insecticidas de uso comun, aplicados sobre grupos de larvas de dos niveles de desarrollo (estadios 1-2 y 3-4). Para determinar la resistencia a los insecticidas se calcularon las DL50, DL90 y pendientes de las regresiones entre mortalidad (probit) y dosis (log). Se verifico la resistencia a los insecticidas estudiados, pues las DL50 al menos duplicaron aquellas en Ovalle y Quillota, localidades donde T. absoluta presento la mayor resistencia en otro estudio. Deltametrina y mevinfos fueron los compuestos menos y mas toxicos, respectivamente. Las larvas de ambos niveles de desarrollo fueron igualmente susceptibles a deltametrina, mientras que las larvas grandes fueron mas resistentes a mevinfos que las pequenas. Los resultados con esfenvalerato y l - cihalotrina sobre larvas grandes, y metamidofos en larvas pequenas fueron muy variables, lo que impidio un buen ajuste probit y la evaluacion de resistencia a estos compuestos en dichos grupos larvarios. El parasito tambien puede haber desarrollado resistencia a insecticidas, lo que puede explicar que en el Valle se hayan restablecido sus poblaciones. La posible resistencia de parasitos, presentes incluso en tratamientos insecticidas a dosis extremadamente altas, podria haber afectado la precision de las regresiones obtenidas, especialmente sobre larvas grandes.

Effects of some Insecticides Applied in Sublethal Concentrations on the Survival and Longevity of Aphidius ervi (Haliday) (Hymenoptera: Aphidiidae) Adults

The effects of four insecticides (dimethoate, pirimicarb, imidacloprid, and spinosad) applied in an ST4 Potter tower at sublethal concentrations (50% of those recommended commercially for aphid control) were studied in the laboratory on the aphidiid Aphidius ervi (Haliday) adults, an important parasitoid of the pea aphid Acyrthosiphon pisum (Harris). The most selective treatment on the hymenopteran was imidacloprid, followed in decreasing order by spinosad, pirimicarb, and finally dimethoate, which quickly eliminated the parasitoid and thus its capacity to produce progeny. Three toxicity groups were distinguished in the study. The least damaging treatment to adults of A. ervi was imidacloprid, followed by a group of medium toxicity made up of spinosad and pirimicarb, and lastly dimethoate, which was extremely toxic to A. pisum.

Efecto del coadyuvante siliconado e insecticidas en el control del chanchito blanco de la vid, Pseudococcus viburni (Hemiptera: Pseudococcidae)

, along with standard insecticides, was studied during the 2005-2006 growing season on Pseudococcus viburni mealybug control in two commercial vineyards in the central valley of the Metropolitan Region of Chile. These vineyards were naturally infested with mealybugs the previous season. A control program included three insecticide sprays, chlorpyrifos at post-harvest (autumn), and before cluster fi lling (summer), and diazinon when shoots were 10-15 cm long in the spring. A standard diazinon treatment without surfactant and a control treatment without spray were included. Levels of uninfested and infested clusters were determined at harvest on 100 clusters per experiment unit. Results were transformed by arcosen√% and subjected to analysis of variance. Means were separated according to Tukeys test. On the basis of the results obtained, the application of trisiloxane in combination with polyether (Break) did not improve the effectiveness of chemical control in areas with a moderate to high infestation of P. viburni.

Control of San Jose Scale Nymphs, Diaspidiotus perniciosus (Comstock), on Almond and Apple Orchards with Pyriproxyfen, Phenoxycarb, Chlorpyrifos, and Mineral Oil

A B S T R A C T The effect of pyriproxyfen, phenoxycarb, chlorpyrifos, and mineral oil in the control of first generation nymphs of the San Jose scale (SJC), Diaspidiotus perniciosus (Comstock), in almond, Prunus dulcis (Mill.) D.A. Webb, and apple, Malus domestica Borkh. orchards was studied in the 2001-2002 season in central Chile. One and two sprays of pyriproxyfen 0.07% and phenoxycarb 0.05% were applied, the first at the beginning of the appearance of nymphs in early spring (biofix), and the other 15 days later, and were compared with one spray of chlorpyrifos 0.08% applied at the biofix. Also, one and two sprays of mineral oil 1% were evaluated, the first applied 7 days after the biofix, and the second 15 days after the first spray. Evaluations were done in the laboratory at the end of the dispersion of first generation nymphs, on December 27 and 28 for almonds and apples, respectively, counting the number of nymphs fixed per lineal meter of new twigs collected at infested sectors, percentage of infested apples, and the number of scales fixed per fruit. Results were subjected to ANOVA and Duncan multiple range tests. At low level infestation, one application of pyriproxyfen 0.07%, phenoxycarb 0.05%, or mineral oil 1% in spring reduced significantly (P ≤ 0.05) the number of nymphs fixed per twig, at a level similar to that of a traditional treatment of chlorpyrifos 0.08%. However, at greater infestations, one spray of pyriproxyfen or mineral oil in spring was insufficient to control ESJ.

Chemical control of Delia platura in Phaseolus vulgaris with seed and soil treatments in Chile

Abstract A field trial with beans ( Phaseolus vulgaris L.) was performed in the Santiago area, to evaluate the insecticidal effect of aldrin, carbofuran, chlorpyriphos, diazinon and lindane, applied to the seed or to the seed furrow, against the bean fly, Delia platura Meigen (Diptera, Anthomyiidae). Plant emergence was reduced with carbofuran and diazinon as a seed treatment, and chlorpyriphos in the furrow, in relation to the checks. All insecticidal treatments reduced the damage to the plants, demonstrating the value of using insecticides for controlling this pest.

Biological parameters of Cydnodromus picanus and Phytoseiulus persimilis raised on the carmine spider mite, Tetranychus cinnabarinus (Acari: Phytoseiidae, Tetranychidae)

V. Tello, R. Vargas, J. Araya, and A. Cardemil. 2009. Biological parameters of Cydnodromus picanus and Phytoseiulus persimilis raised on the carmine spider mite Tetranychus cinnabarinus (Acari: Phytoseiidae, Tetranychidae). Cien. Inv. Agr. 36(2):277-290. The postembryonic development, consumption and life table parameters of Cydnodromus picanus Ragusa and Phytoseiulus persimilis (Athias-Henriot) were studied at 29.44 ± 1.47 °C and 42.35 ± 5.01% of RH with a photoperiod of 14:10 h (L:D) in order to evaluate the potential of these predators for feeding on the carmine spider mite Tetranychus cinnabarinus (Boisduval). Eggs, larvae and protonymphs of T. cinnabarinus may be optimal food for C. picanus, which obtained survival rates of 100%, 97% and 93%, respectively, on them. The survival of P. persimilis was around 6.7% with diets based on eggs, larvae and protonymphs, showing a high mortality level by dehydration when fed with eggs. The time of the postembryonic development was signifi cantly shorter (p < 0.05) for C. picanus than for P. persimilis when they were fed with eggs, larvae and deutonymphs of T. cinnabarinus. When fed with eggs and a combination of different stages of T. cinnabarinus, the intrinsic rate of growth (r m ) was signifi cantly higher (p < 0.05) for C. picanus (0.289 and 0.307, respectively) than for P. persimilis (0.019 and 0.025, respectively). The values of the fi nite rate of growth (λ) were also signifi cantly (p < 0.05) higher for C. picanus (1.34 and 1.36) than for P. persimilis (1.02 and 1.03) when they were nourished with eggs and a mixed diet, respectively. The high values of r m and λ found for C. picanus in the experimental conditions are indicators of the possible control that this phytoseiid mite, as a predator of T. cinnabarinus, would potentially offer under the conditions of lower relative humidity encountered in the arid zone of the desert of Chile.

Malezas del Género Datura como Factor Epidemiológico del Virus del mosaico de la alfalfa (AMV), Virus del mosaico del pepino (CMV) y Virus Y de la papa (PVY) en Solanáceas Cultivadas

En Santiago, Chile (33o34? lat. Sur, 70o38? long. Oeste, altitud 625 m.s.n.m.) se colectaron plantas de chamico (Datura stramonium y D. ferox) para determinar la presencia del Virus mosaico de la alfalfa (AMV), Virus mosaico del pepino (CMV) y Virus Y de la papa (PVY) mediante analisis doble stranded RNA (dsRNA) y ELISA. Ambas malezas fueron positivas a los tres tipos de virus y los porcentajes de infeccion estuvieron entre 20-30%, excepto para PVY en D. stramonium que fue de 5%. Bajo condiciones controladas, el afido vector Myzus persicae Sulzer transmitio CMV desde D. ferox a tomates (Lycopersicon esculentum Mill.) y pimientos (Capsicum annuum L.), sin embargo no lo transfirio a papas (Solanum tuberosum L.). Semillas de plantas positivas de D. stramonium y D. ferox no transmitieron CMV, AMV ni PVY. En campo no se correlaciono la presencia de chamico infectado y vuelo de los afidos vectores con los niveles de infeccion de tomate, pimientos y papas. La capacidad de infeccion de estos insectos pudo afectarse por la direccion de los vientos y su relacion con la ubicacion de las plantas cultivadas. Las plantas de chamico, especialmente D. ferox, deben ser controladas no solo por las perdidas economicas producidas por la competencia maleza-cultivo, sino que ademas por ser hospederos alternativos de CMV, AMV y PVY. Desde un punto de vista epidemiologico, el control no solo debiera circunscribirse a plantas de chamico del potrero sino que tambien aquellas de las inmediaciones, especialmente en la linea de direccion de los vientos.

Sucking insects damaging jojoba, Simmondsia chinensis (link) Schneider, and their natural enemies, in the North Central and Central regions of Chile

Abstract This article reports the results of a periodical survey of sap-sucking insects of jojoba [ Simmondsia chinensis (Link) Schneider] at five locations in the North Central and Central regions of Chile and describes their damage to the plants. The diaspidid Aspidiotus nerii Bouche, which was commonly found in two of the locations (Casablanca, near Valparaiso, and Curacavi, near Santiago) was potentially the most severe pest of the crop, as it damages the fruits directly. Next in importance as pests, because of their reproductive potential, were the aphids Aphis craccivora Koch and Myzus persicae Sulzer, which were found on leaves and young shoots, in Casablanca, Curacavi, and Hacienda Camarones (IV region). Other species of certain importance because of their numbers were the pentatomid Acledra albocostata (Spinola) and the cicadellid Balclutha sp. (both common in Casablanca and Curacavi). When ovipositing, the cicadid Tettigades chilensis Arm. & Serv. (collected in Las Cardas, in the IV region), was found to produce deep wounds with the oviscapt on branches, which affected their vascular system. The scelionid micro-hymenopteran Trissolcus scuticarinatus Costa Lima was found parasitizing eggs of hemipterans throughout the locations studied. Except in Casablanca, the predatory activity on aphids of the coccinellids Eriopis connexa Germ., Hippodamia variegata Guer., and Scymmus bicolor Goeze was observed in all locations surveyed, including Agua Amarilla, a southern location in the IV region.

Evaluation of chemical and cultural control for noctuid larvae in Chilean artichokes produced for foreign markets

Abstract The presence of noctuid larvae on artichoke ( Cynara scolymus L.) heads, particularly Copitarsia consueta Walker, but also Syngrapha gammoides (Blanchard), Agrotis bilitura (Guenee), Peridroma saucia (Hubner), and Peridroma chilenaria Angulo & Jana-S., has caused the rejection of Chilean artichokes prior to shipping to foreign markets. This study compares the proportions of damage caused by noctuid larvae throughout the harvest period of fresh artichokes produced for markets in the northern hemisphere. A field trial was conducted in the central valley of Chile, comparing several practices consisting of combinations of traditional or intensive weed control and insecticide use. The damage levels were measured on six harvest dates during the 1986 season. The more intense weed control treatment significantly reduced damage by noctuid larvae. Methomyl sprays prior to the first three harvests further reduced damage levels. A combination of methomyl sprays and intensive weed control was the most efficacious treatment. It is estimated that intensive weed control combined with insecticide sprays similar in action to methomyl may help to decrease the number of insecticide applications required to reduce noctuid species populations occurring on artichoke crops under the traditional management of only two hoe weeding controls.

Evaluation of Insecticide Activity of Two Agricultural Detergents against the Long-Tailed Mealybug, Pseudococcus longispinus (Hemiptera: Pseudococcidae), in the Laboratory

Se evaluo el efecto insecticida de los detergentes agricolas SU 120 y Tecsa Fruta sobre hembras y ninfas II de Pseudococcus longispinus (Targioni & Tozzetti) en laboratorio. La mortalidad a las 24 h se sometio a analisis Probit para obtener las concentraciones letales medias (CL50). Para Tecsa Fruta se asperjo un volumen de 9,5 mL de solucion, mientras que para SU 120 se evaluaron 2, 4 y 8 mL 100 mL-1 de solucion. La mortalidad fue directamente proporcional a la concentracion utilizada. Las ninfas II fueron mas susceptibles que las hembras a ambos detergentes. Las CL50 para Tecsa Fruta fueron 17,9 mL 100 mL-1 para hembras y 5,4 mL 100 mL-1 para ninfas II, mientras que para SU 120 fueron 3,1; 1,6 y 1,9 mL 100 mL-1 en hembras, y 0,8; 0,5 y 0,5 mL 100 mL-1 (para 2, 4 y 8 mL, respectivamente) en ninfas II. Para estas no hubo diferencias significativas entre volumenes, y para hembras las CL50 con 4 y 8 mL de solucion no fueron estadisticamente diferentes entre si, aunque estos dos volumenes fueron estadisticamente inferiores al tratamiento con 2 mL. Para una misma concentracion de SU 120, la mortalidad de hembras aumento con volumenes mayores de aspersion. SU 120 presento un efecto insecticida significativamente mayor que Tecsa Fruta en ninfas II y hembras de P. longispinus. Las ninfas II fueron el estadio mas susceptible. Los resultados sugieren que seria posible reducir la concentracion de detergente con volumenes mayores de aspersion para lograr mortalidades similares.