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El nuevo libro titulado "Manejo integrado de insectos herbívoros en sistemas ganaderos sostenibles" puede ser descargado gratuitamente a través del siguiente enlace: http://www.cipav.org.co/publicaciones/publicaciones.html#libros
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El propósito de esta publicación es compartir las experiencias y aprendizajes sobre el control de insectos herbívoros y otros organismos plaga en sistemas ganaderos sostenibles, utilizando métodos como el control biológico, mecánico, físico, y evitándo en lo posible el uso de productos de síntesis química.
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Repeated use of the same class of pesticides to control a target pest is a form of artificial selection that leads to pesticide resistance. We studied insecticide resistance and cross-resistance to five commercial insecticides in each of six populations of the red flour beetle, Tribolium castaneum . We estimated the dosage response curves for lethality in each parent population for each insecticide and found an 800-fold difference among populations in resistance to insecticides. As expected, a naïve laboratory population was among the most sensitive of populations to most insecticides. We then used inbred lines derived from five of these populations to estimate the heritability ( h ² ) of resistance for each pesticide and the genetic correlation ( r G ) of resistance among pesticides in each population. These quantitative genetic parameters allow insight into the adaptive potential of populations to further evolve insecticide resistance. Lastly, we use our estimates of the genetic variance and covariance of resistance and stochastic simulations to evaluate the efficacy of “windowing” as an insecticide resistance management strategy, where the application of several insecticides is rotated on a periodic basis.
Las hormigas cortadoras de hojas, Atta y Acromyrmex, son los herbívoros más importantes en los trópicos. En este estudio se comparan los efectos de dos métodos no químicos sobre la sobrevivencia y actividad de nidos de Atta cephalotes (Formicidae:Myrmicinae). Un total de 83 nidos activos de A. cephalotes fueron asignados de forma aleatoria a uno de tres tratamientos: 1) incorporación de un material compostable al suelo; 2) remoción y mezcla de la capa superficial del suelo (método convencional) y 3) placebo o control (sin tratamiento). Después de tres meses, los porcentajes de nidos eliminados con cada uno de los tratamientos fueron 26,5; 9,6; y 3,6; respectivamente. Un análisis de varianza de medidas repetidas mostró una diferencia significativa entre las colonias de hormigas sometidas a los tratamientos compostado y remoción mecánica en relación con el placebo. Esto debido a la destrucción de las pistas de forrajeo, de las aberturas, cámaras y túneles. Sin embargo, el más fuerte efecto fue observado con el compostado. Basado en estos resultados sobre los nidos de A. cephalotes y su efecto potencial de enriquecer el suelo, el tratamiento compostado puede representar una práctica sustentable y ecológicamente amigable en el control de hormigueros de Atta.
The effect of management was evaluated to prevent leucaena becoming an invasive plant. For five years, the evolution of two systems was studied: 1) tree legume Leucaena leucocephala c v. Peru in silvopastoral system, where it occupied 100 % of the area, associated with Brachiaria brizantha cv. Marandú for cattle fattening; 2) tree legume Leucaena leucocephala cv. Peru, where it occupied 100 % of the area, associated with Brachiaria brizantha cv. Marandú without being grazed. A random block design was applied, with five replications. Indicators in the leucaena-brachiaria system with animal grazing were better, at the beginning and at the end of the experiment, with a decrease in the depopulation of 1 plant/m² (P = 0.0012), higher grass population 11.2/m² (P = 0.0014) and low presence of weeds 1 plant/m² (P = 0.0039), which was better in the system without grazing. Leucaena component had a different performance, according to the studied system. In the system under grazing, yield of brachiaria base grass was always superior (2.2 and 3.0 t/ha DM) with respect to the non-managed system, at the beginning (P = 0.0028) and at the end of the experimental stage. The same happened with the presence of natural grass 0.40 t/ha DM (P=0.0011), which disappeared at the end. Weeds had a higher presence in the non-managed area 0.31 t/ha DM (P = 0.0101) at the beginning of the study. It is concluded that the technological proposal for the management of systems with Leucaena leucocephala in silvopastoral systems is a functional and feasible option to apply so that this species does not become invasive.
Colombia has opened its markets to international competition by signing several free trade
agreements. This condition has generated great pressure on the dairy sector, which must be competitive in a
globalized market. In the year 2014, Colombia produced 6.717 million L of milk and per capita milk consumption
was 143 L. There are an estimated 99,000 dairy producers in specialized systems and 250,000 in dual-purpose
systems. Specialized dairy production is found mainly in pastoril systems in the highland tropics (>2000 m
elevation) with pastures of Kikuyu grass (Pennisetum clandestinum Hoschst ex Chiov) and the predominant
dairy breed is Holstein Friesian. Average milk production is 12 to 14 kg/d with a stocking rate between 1 and
2 cows/ha. Dual purpose dairying under grazing systems occurs mainly in the low (<1200 m.) and medium
high (1200 to 2000 m.) tropics, and uses crossbreed cows (Bos indicus × Bos taurus), with once a day milking
with the calf present. The calf sucks residual milk and grazes with the mother until midday or mid-afternoon.
Milk production is low (3 to 5 L/d) and lactation length is short (<280 d). Lowest unit costs of milk production
(<U$ 0. 27/L) is obtained in low input systems and low productivity. These systems account for more than 66%
of the producers and 54% of the milk produced nationally. The concentrations of milk fat and protein and
standard plate count (SPC) are higher for dual-purpose systems (3.7%, 3.3%, and 884.993/mL) than for
specialized dairies (3.5%, 3.1%, and 395.551 SPC/mL). Milk somatic cell count (SCC) is between 400,000 and
600,000 cells/mL nationally. Milk transportation costs are high due to the geographical dispersion of dairy
producers and the low volumes they deliver (<200 L/d). Although Colombia has been declared free of foot and
mouth disease with vaccination, its admissibility to international markets may be limited by other diseases such
as brucellosis (prevalence >4%) or tuberculosis. To compete in international markets Colombia should
consolidate milk production systems, improve milk quality (solids content, hygiene), increase volumes of
delivery by supplier and achieve zones of sanitary excellence.
El taladrador de las meliáceas, Hypsipyla grandella (Zeller), taladra los brotes de árboles en la familia de las caobas (Meliaceae), especialmente las caobas (Swietenia spp.) y los cedros (Cedrela spp.). Es una plaga económica importante, y ha sido el objetivo de investigaciones en muchos países tropicales. Es la única especie de Hypsipyla en Florida, donde es una plaga de caoba antillana (Swietenia mahagoni Jacquin), un árbol nativo que es frecuentemente plantado como un árbol de sombra. Este documento, EENY337, es uno de una serie de publicaciones del Departamento de Entomología y Nematología, UF/IFAS Extensión. Fecha de primera publicación: diciembre 2004. EENY337/IN614: El taladrador de las meliáceas, Hypsipyla grandella (Zeller) (Insecta: Lepidoptera: Pyralidae: Phycitinae) (ufl.edu)
1. Generalist herbivores feed on a wide and diverse set of species, but fine-scale foraging patterns may be affected by the interplay between the quality, quantity and spatial distribution of host-plants.
2. We examined the foraging patterns of a prevalent Neotropical herbivore, the leaf-cutter ant Atta laevigata, in the Brazilian Cerrado savannas and determined if patterns observed are in concert with central-place foraging predictions.
3. Our results showed that A. laevigata acts as a polyphagous but highly selective herbivore, with ant attacks often resulting in partial defoliation of less-preferred species and full defoliation of preferred ones.
4. We found, for the first time, a strong and positive relationship between the relative attack frequency on plants from preferred species and foraging distance to the nest. This suggests a balance between the quality of plant resources harvested and costs involved in their transportation. We also observed that colonies focused their harvest on preferred species in months with low availability of young leaves. Consequently, high herbivory rate was more frequent in plants attacked far away from the nest and in dry months.
5. These assessments highlight that Atta colonies may become more selective as foraging distance to the nest increases and in response to fluctuations in the availability of palatable resources throughout the year.
6. Finally, our results indicate some dissimilarities in the foraging behaviors of A. laevigata when compared to other locations, suggesting that widely distributed herbivores may modify foraging strategies across their geographic range.
Relatively few native trees and palms are actively managed by cattle ranchers in Latin America and the Caribbean. However, throughout the region the need for reducing heat stress and adapting to climate change has provided a strong motivation for ranchers to plant or maintain more trees and palms on their lands. This chapter describes a new approach for enhancing the density and diversity of native woody plants in cattle dominated landscapes. The concept of focal species is applied to identify a set of native trees and palms of global conservation concern that can be planted or managed in silvopastoral systems and riparian buffers to enhance the conservation value of these agricultural landscapes. This agroforestry version of the focal species concept combines pragmatic criteria such as the direct benefits of trees for livestock production systems with cultural and aesthetic values, together with the provision of habitat and food resources for wildlife. The following sections focus on outstanding focal species: Section 3 describes the early growth and survival of two focal species planted in live fences: a highly endangered and valuable timber tree (big-leaf mahogany, Swietenia macrophylla) and an endemic nitrogen fixing tree (Mimosa trianae) with exceptional performance in silvopastoral systems, and Sect. 4 highlights the contribution of Acrocomia aculeata palms in pasturelands as a food source of high nutritional value for livestock. Pasturelands offer a great opportunity for ecological restoration in Latin America. Promoting a larger diversity of native trees and palms in silvopastoral systems and restoration projects is an important step in mainstreaming biodiversity into sustainable cattle ranching.
