Influence of temperature, humidity and rainfall on field population trend of Stomoxys calcitrans (Diptera: Muscidae) in a semiarid climate in Mexico
The influence of temperature, humidity and rainfall on field population trend of stable fly, Stomoxys calcitrans, over three consecutive years in two dairy farms located in semiarid climate in Aguascalientes State, in Mexico, were determined. The dairies were visited weekly between April 1999 to March 2002, on each occasion 10% of the dairy cows were selected making direct counts of stable flies observed front the legs. The occurrence of stable fly adults from weekly counts was divided in four population phases: population increasing phase I (first peak), fluctuation phase, population increasing phase II (second peak) and population decreasing phase, for each year of study. Pearson's correlation analysis was developed (P < 0.01) between weekly average fly number per cow and mean temperature, mean relative humidity and rainfall recorded from one to four weeks before count in each population phases. The population increasing phase I, was observed in spring-summer period, in where relative humidity had significant correlation indices (r = 0.6 to 0.8), the first peak occurred in September, June and August, of each year studied, respectively. The population-decreasing phase was observed between last weeks of summer and in the fall, showed high correlation indices with temperature (r = 0.9). No significant correlations were founded with the rainfall over the study.