Navegando por Autor "Avelar, Maria Betania Lopes"

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Spatial and temporal dynamics of coffee-leaf-miner and predatory wasps in organic coffee field in formation
(Universidade Federal de Santa Maria, 2011-04) Scalon, João Domingos; Avelar, Maria Betania Lopes; Alves, Gabriela de Freitas; Zacarias, Maurício Sérgio
The coffee production is an economic mainstay for many countries in the world. Brazil is the world’s largest producer and exporter of coffee, being responsible for about 25% of the world production. It is well known that coffee plantations are susceptible to more than 850 fungal and insect pests. Among these pests, the most important significant throughout Brazil is the coffee-leaf-miner, [Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae)]. It is estimated that the loss in yield due to infestation by L. coffeella moths can increase to as much as 80% in areas where the coffee-leaf-miner larvae are not controlled. Though it is effective, the chemical control of the pest substantially increases the cost of production and constitutes a risk to the environment. The knowledge about the spatial- temporal dynamics of coffee-leaf-miner and predatory wasps may provide valuable information about the biological management pest context. One way to investigate the spatial- temporal synchronism of predator and prey is to calculate and compare an index of spatial randomness within a sequence time. This paper advocates using the Morisita’s index, coupled with the bootstrap method, in a temporal sequence to characterize the spatial- temporal dynamics of coffee-leaf-miner and predatory wasp (Hymenoptera: Vespidae) in one hectare of an organic coffee plantation. The results showed that coffee- leaf-miner and predatory wasps presented a seasonal behavior with a temporal synchronism. The results also showed that both new and preyed mines were aggregated during the peak population (dry season). There was little evidence for space- time interaction between coffee-leaf-miner and predatory wasps.
Spatial distribution of the coffee-leaf-miner (Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842)) in an organic coffee (Coffea arabica L.) field in formation
(Editora UFLA, 2011-09) Scalon, João Domingos; Alves, Gabriella de Freitas; Avelar, Maria Betania Lopes; Zacarias, Mauricio Sergio
Coffee production has been one of the economy pillars of many tropical countries. Unfortunately, this crop is susceptible to infestation by the coffee-leaf-miner (Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842)) which causes severe damage to coffee plantations with losses that may reach 80% of the total production. In recent years, researchers have been trying to develop practices for minimizing the use of pesticides in the coffee-leaf-miner control. It is well known that the understanding of the spatial distribution of insects may be important in the context of biological control of pests. The aim of this work is to use spatial statistical methods for characterizing the spatial distribution of the coffee-leaf-miner in a plantation of organic coffee (Coffea arabica L.). This work uses the number of mined leaves taken from a grid of 35 sampling locations from one hectare of an organic plantation of coffee in the second year of its implantation during the annual peak population (September 2006) of the coffee-leaf-miner. A geostatistical method (semivariogram) was used to characterize the spatial variability of the coffee-leaf-miner in an organic coffee field in formation. The results showed that the coffee-leaf-miner population was randomly distributed in the field during the annual peak population.