Distribución espacial de la broca del café

De Wikinsecta

SPATIAL DISTRIBUTION OF THE COFFEE BERRY BORER Hypothenemus hampei ON COFFEE TREES, ANS ITS IMPLICATIONS FOR SAMPLING

R. Ruiz1 , A.E. Bustillo1 & P.S. Baker2 .
1Centro Nacional de Investigaciones de Café, A.A. 2427, Manizales, Colombia. E-mail: rrcarden@carpa.ciagri.usp.br ; 2CABI bioscience, Silwood Park, Ascot SL57TA, UK


An important aspect to control any insect is to understand their movements. The coffee berry borer (CBB) is the most serious pest of commercial coffee, threatening a production of about 15 billion dollars per year worldwide. A descriptive analysis on the distribution of its attack during four years (1995-98) in a coffee plot censured monthly, located in the central colombian zone, allowed to identify several phases into the advance of the infestation. On the study plot, infestation started very slowly and the proportion of infested trees was below 5% for the initial seven months of observation. However, during the next two months, infestation increased very fast in percentage of perforated fruits, as well as in the proportion of infested trees. The proportion of infested trees went up to 70%, caused probably by borer populations arriving from neighbor plots (300 m away) which were cut down at that time. The highest infestation was reached on September 1997 (98.2% of infested trees), after a dry period generated by “El niño”. Counts of infested berries fitted the negative binomial distribution in 29 out of 40 dates, with k values ranging between 0.0129 and 1.3511, but it was not possible to find a k common value for all dates. Besides, there was a discontinuity in the fitting through consecutive dates. Fitting of counts to Taylor`s power law was significative in all cases showing a spatial pattern generally aggregated (b values between 1.25 and 2.18). Variability study for total and infested berries both to the tree and branch level, was always significantly higher (F<0.05) than the latter. There was a explicit trend of CBB distribution following the distribution of coffee berries through time, which occupy a progressively greater space as the tree produces more branches and nodes, constituting one of the fundamental problems of controlling this pest. Significantly higher density of CBB was found on the nodes nearest the main stem in each branch. A function describing the behavior of infestation in agreement with the age of berries was fitted following a geometric model. In conclusion, the spatial and temporal pattern of CBB attack is predicted upon the complex architecture and phenology of the coffee plant, and the unpredictable rainfall pattern, which determine flowering and development of berries.
Index terms: Dispersion, IPM, Scolytidae, Taylor`s Power Law.

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