ABSTRACT
Introducción: Mantener poblaciones de insectos depredadores en el agroecosistema ofreciéndoles presas y recursos alimenticios provenientes de las plantas es importante para mejorar el control biológico y contribuir con la conservación. Objetivo: Determinar si el consumo de presas y recursos alimenticios florales potencia los atributos biológicos del depredado Hippodamia convergens. Métodos: Las larvas de Hippodamia convergens fueron alimentadas con dos especies de áfidos, mientras que los adultos fueron alimentados con áfidos, espigas de maíz y dos especies de plantas no cultivadas. La presencia de azúcar en el intestino del depredador se comprobó mediante la prueba de antronas frías, y la presencia de polen mediante el método de acetólisis. Los experimentos demográficos se realizaron durante los primeros 40 días después de la emergencia de la hembra bajo condiciones controladas (25 °C ± 0.5; 75 % ± 1.75 HR; L12:D12). Resultados: H. convergens no consumió fructosa de Sorghum halepense, Parthenium hysterophorus o Zea mays, sino únicamente polen. En condiciones controladas (25 °C ± 0.5, 75 % ± 1.75 HR), el tiempo de desarrollo (huevo-adulto) del depredador fue más corto (21.36 días) cuando consumió Rhopalosiphum maidis en lugar de Uroleucon nigrotibium (24.6 días), mientras que la supervivencia (L1- adulto) y la proporción sexual no cambió. La fecundidad promedio fue mayor (55.5 huevos / 40 días) al consumir U. nigrotibium con polen de P. hysterophorus, que solo U. nigrotibium (22.5 huevos / 40 días), o R. maidis con polen de Zea mays (11 huevos / 40 días). La tasa intrínseca de crecimiento natural fue mayor al consumir U. nigrotibium con polen de P. hysterophorus (0.055), que U. nigrotibium (0.034) o R. maidis con polen de Z. mays (0.019). La tasa de depredación (L1-L5) fue mayor al consumir R. maidis (0.65) que U. nigrotibium (0.51). Conclusiones: Las especies de áfidos y su combinación con polen de plantas no cultivadas afectan de manera diferente el tiempo de desarrollo, reproducción y tasa de depredación de H. convergens.
Introduction: Keeping populations of predatory insects in the agroecosystem by offering them prey, as well as food resources from plants, is important for enhancing conservation biological control. Objective: To determine if the consumption of prey and floral food resources enhances the biological attributes of the predator Hippodamia convergens. Methods: We fed the beetle larvae two species of aphids; and the adults were fed aphids, maize tassels, and two non-cultivated plant species. We checked gut sugar in the predator by the cold anthrone test and pollen presence by the acetolysis method. Demographic experiments were done in the first 40 days after female emergence, under controlled conditions (25 °C ± 0.5; 75 % ± 1.75 Relative Humidity; Light 12 h: Darkness 12 h). Results: H. convergens did not consume fructose, but only pollen from Sorghum halepense, Parthenium hysterophorus or Zea mays. Developmental time (egg-adult) of the predator was shorter (21.4 days) when it consumed Rhopalosiphum maidis than Uroleucon nigrotibium (24.6 days); survival (L1-adult) and sex ratio did not change. Average fecundity was higher (55.5 eggs / 40 days) when consuming U. nigrotibium with pollen from P. hysterophorus, than U. nigrotibium (22.5 eggs / 40 days) or R. maidis with pollen from Zea mays (11 eggs / 40 days). The intrinsic rate of natural growth was higher when consuming U. nigrotibium with pollen from P. hysterophorus (0.055), than U. nigrotibium (0.034) or R. maidis with pollen from Z. mays (0.019). Predation rate (L1-L5) was higher when consuming R. maidis (0.65) than U. nigrotibium (0.51). Conclusions: Aphid prey species and its combination with pollen from maize and non-cultivated plants affected development time, reproduction, and predation rate of H. convergens.
Subject(s)
Animals , Coleoptera/growth & development , Pest Control, Biological/methods , ColombiaABSTRACT
The purpose of this study was to develop a pollen preparation methodology with a high proportion of intact pollen of species for the genus Passiflora subg. Passiflora. Thus, flower buds were collected near anthesis, from the species: P. alata, P. edulis, P. foetida, P. giberti, and P. setacea, fixed in ethanol-acetic acid mixture (3:1) and treated in 10%-20% aqueous sodium hydroxide, or acetolyzed. The pollen treated with 10% sodium hydroxide resulted in an average of 96% intact pollen grains in all species, however, after acetolysis an average percentage of 98% broken pollen was observed. Data obtained in pollen measurements did not change with the new methodology. It is therefore evident that the proposed methodology for pollen preparation based on sodium hydroxide was effective, as it allowed the visualization of a significant amount of intact pollen, thus promoting morpho-palynological studies of these species.
Este estudo teve como objetivo elaborar uma metodologia, para obter preparos polínicos com alta frequência de polens íntegros de espécies representantes do gênero Passiflora subg. Passiflora. Dessa forma, botões florais foram coletados, próximo à antese, das seguintes espécies: P. alata, P. edulis, P. foetida, P. giberti e P. setacea, fixado em solução etanol-ácido acético (3:1) e tratado em solução aquosa de hidróxido de sódio (10 e 20%) ou acetolisados, independentemente. Os preparos palinológicos, quando tratados com hidróxido de sódio a 10%, evidenciaram, em todas as espécies, média de 96% de polens íntegros, em contrapartida, quando acetolisados foi observada uma percentagem média de 98% de polens rompidos. Os dados referentes a mensurações polínicas não sofreram alterações com a nova metodologia. Evidencia-se, dessa forma, que a metodologia proposta, para preparações polínicas à base de hidróxido de sódio, foi eficiente, pois promoveu a visualização de uma quantidade significativa de polens íntegros, favorecendo assim o estudo da morfologia polínica nessas espécies.