Spodoptera frugiperda (J.E. Smith) is the pest insect that produces the highest losses in maize production in the tropics and neotropics. Its control in Colombia comprises about 10% of the total production costs. The aim of this study was to determine the economic injury level (EIL) and define action thresholds (ATs) for this insect pest in the maize hybrids 30F35R and 30F35HR (with Cry1F protein) in Espinal, Colombia. In two sowing cycles, a completely randomized design was established for each maize hybrid to measure their yield response at four insect population levels (a control without any applications of insecticides and applications at 2, 5, and 10 larvae per 10 plants). For 30F35R, an inverse relationship was found between levels of infestation and yields; meanwhile, for 30F35HR, only during the first cycle this relationship was found. The EIL calculated for 30F35R showed an average of 2.6 and 1.9 larvae per 10 plants in the first and second cycles, respectively, and 2.8 for 30F35HR in the first cycle. Two ATs were established, one in the period from 0 to 20 days after emergence (DAE) and another from 20 to 40 DAE. The threshold for 30F35R from 0 to 20 DAE showed an average of 1.8 larvae per 10 plants in both cycles, while, from 20 to 40 DAE, it was 2.0 and 1.7 in the first and second cycles, respectively. In 30F35HR, the thresholds were 2.1 and 2.5 larvae per 10 plants on average for both periods of the first cycle, respectively. These results can be considered as a tool within integrated pest management that also includes biological and cultural control strategies.
El mango es una de las frutas tropicales con mayor producción a nivel mundial; en Colombia es un cultivo con gran potencial de exportación. Sin embargo, insectos plaga como los trips, pueden incidir en su calidad y producción. En esta investigación se evaluó la relación de la fluctuación poblacional de trips (Frankliniella cf. gardeniae) con las condiciones climáticas, la fenología del mango (var. Yulima y Tommy) y los hospederos alternos en el Guamo y San Luis (Tolima). Semanalmente se muestrearon trips en inflorescencias, hojas jóvenes de mango y en arvenses asociadas, se registraron los estados fenológicos del cultivo, las condiciones climáticas (temperatura, humedad relativa y precipitación) y se determinó la probabilidad de presencia de trips en inflorescencias de mango. En total se recolectaron 8.609 individuos de trips entre adultos y ninfas. La fluctuación poblacional de F. cf. gardeniae presentó relación positiva con la floración (r = 0,79 var. Yulima y Tommy) y la temperatura (r = 0,43 var. Yulima; r = 0,48 var. Tommy). Se registraron los géneros fitófagos Frankliniella y Haplothrips, en las arvenses Desmodium tortuosum y Melochia parvifolia. Las flores y frutos hasta tamaño de 8 mm fueron las más susceptibles al ataque del insecto. Finalmente, la mayor probabilidad de presencia de trips en inflorescencias de mango presentó dos períodos marcados, de 7 a 63 y de 161 a 203 días después de floración. F.cf. gardeniae en mango se comportó como una plaga ocasional, presente cuando la fuente de alimento estuvo disponible y las condiciones climáticas fueron adecuadas.
El objetivo del presente estudio fue determinar los niveles de preferencia de especies de trips por estructuras aéreas de las plantas de algodón. Para ello, en el valle cálido del alto Magdalena en la región Andina de Colombia, se coleccionaron e identificaron especies de trips asociadas al sistema productivo de algodón. Se muestrearon 60 fincas productoras en fase de llenado de cápsulas, donde la planta de algodón presentó los microhábitats: hoja joven, botón floral, flor y cápsula. Se realizaron análisis de agrupamiento de Bray-Curtis y pruebas no paramétricas de Kruskall-Wallis. Las especies registradas fueron Thrips palmi, Scirtothrips dorsalis y Frankliniella cephalica. Thrips palmi (n=3595; µ = 14,97 ± 32,35) fue la más frecuente, seguida por S. dorsalis (n = 856; µ = 3,56 ± 6,35) y Fr. cephalica (n = 405; µ = 1,68 ± 9,13). Thrips palmi se encontró en todos los microhábitats; S. dorsalis prefirió cápsula, seguido de hoja joven y botón floral. Frankliniella cephalica mostró preferencia por las flores. El presente estudio reveló la acción fitófaga de T. palmi y S. dorsalis como insectos con preferencia intra-hospedante del tipo generalista, hacia hojas (filofagía), botones florales (antofagía) y cápsulas (carpofagía). Frankliniella cephalica se comportó como especialista en flores (antofagía) de algodón.
Interactions among pests could differ among types of citrus hosts. Also, the climate factors may affect the population fluctuation of these pests. Therefore, the aim of this study was to establish the potential vulnerability of citrus cultivars to pest pressure over time as an aid to pest management. During 48 months between 2017 and 2020, pest arthropods from the families Aphididae, Liviidae, Gracillariidae, Aleyrodidae, Diaspididae and the order Acari were sampled bi-weekly in a common orchard with 32 cultivars [(16 citrus scion varieties of three citrus types (9 oranges, 4 mandarins, and 3 limes-lemons) grafted onto two rootstocks (CPB 4475 and SxE)]. Percentage of presence of each arthropod taxon was determined by visually inspecting five leaf buds or five leaves or five fruits, or combination of those, in two of six randomly sampled trees, in each one of three 210 m 2 plots established for each cultivar, for a total of 192 trees in each sampling. Percentages of presence of each arthropod taxon on each tree among cultivars were compared and correlations between these percentages and the climatic factors temperature, relative humidity, and rainfall recorded on a daily basis, were calculated. Among the three citrus types, mandarins had the greatest presence of aphids; oranges had the greatest presence of whiteflies, leafminers and Diaphorina citri, and limes-lemons had the greatest presence of mites. Presence of mites, aphids, D. citri and leafminer were positively correlated to relative humidity. Among mandarin varieties aphids had higher percentage of presence on Oneco and Owari Satsuma and among orange varieties Pineapple had a higher presence of it than the other varieties in study. Leaf miner had higher presence on Orange Sweet variety grafted on SxE rootstock than on any other orange cultivar.
Leaf spot or black spot (BS) in avocado, caused by the fungus Pseudocercospora purpurea (Cooke) Deighton, is one of the main sanitary limitations for the production of avocado, particularly for the Antillean cultivars (Lorena, Choquette, Santana, and Semil 44) in the northern region of the department of Tolima, Colombia. During 2014-2017, different experiments were carried out in the field, aiming to determine the period of higher fruit susceptibility, the effect of pruning on inoculum reduction, and chemical molecules with a high degree of control, adjusting their chronology and frequency of application. The results allow the technical, economic, and environmental implementation and validation of a chemical strategy for management of this disease. The management strategy carried out by Agrosavia reported a 10% lower incidence of BS in fruits, compared to the one carried out by producers, and a 23.75% return, due to the increase in high quality fruits. In the latter, DMI fungicides (demethylation inhibitors), even without resistance reports, and fungicides with a mixture of two active ingredients (DMI and QoI) in interspersed application and sometimes in conjunction with CuOCl during periods of higher susceptibility to BS were used, aiming to reduce the resistance induction risk in P. purpurea.
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