Assessing areas of climatic stress for Ceratitis capitata (Diptera: Tephritidae) in Argentina

MARÍA T. VERA; RAFAEL RODRÍGUEZ; DIEGO F. SEGURA; JORGE L. CLADERA

Foz do Iguazu, Brasil

Congreso; XXI International Congress of Entomology; 2000

Dynamic simulation models combining meteorological databases with the biological constrains for development imposed by abiotic factors are used to determine the potential risk of establishment of exotic pests. In areas where the pest is already present they may give an idea of which are the potential abiotic stress factors and their probable effect on population dynamics. The assessment of areas under climatic stress for the Mediterranean fruit fly, Ceratitis capitata, in Argentina was attempted here with the simulation program CLIMEX, combining the potential population growth for a given range of temperature and soil moisture and the negative effect on growth (stress) during adverse conditions. In addition to using CLIMEX, areas under stress were determined by considering the duration along the year of the period with extreme temperatures and humidities (duration of extreme conditions, DEC). Summer and winter precipitation levels were also included in this second analysis as potential deleterious factors. CLIMEX and DEC were run using a meteorological database of 24yr-average recordings from 152 meteorological stations located along the country. Both approaches showed areas where C. capitata should not be present due to excess of cold during winter, and suggested that Argentina could be divided into unfavorable, marginal and favorable areas, but CLIMEX predictions seemed to over estimate winter mortality. With respect to variables other than cold (soil moisture, heat stress), CLIMEX output showed no detrimental effect, whereas DEC revealed possible reductions in abundance due to summer rainfall in two areas and winter precipitation in one of these areas. It also revealed areas with deficit in humidity and areas with excess of heat. When daily meteorological information was used to analyze both seasonal and interannual variation in some particular locations, the detrimental effect of relative humidity, precipitation and heat was shown to be important also by CLIMEX. Additionally indexes values presented a great variability among years. In conclusion, the two approaches used here show habitat heterogeneity and suggest that winter or summer temperatures, precipitation and deficit of humidity can be stressing factors in different areas of Argentina. This information may be used to improve pest control efforts, especially considering the climatic variability among years within areas.