The influence of meteorological factors on the fluctuation and dynamics of Anastrepha spp

Abstract

The influence of meteorological factors (maximum, minimum, and average temperatures, relative humidity, rainfall and wind velocity) on the fluctuation and dynamics of population of Anastrepha spp. (Diptera:Tephritidae) was studied in the peach orchards in Pelotas, Canguçu and Piratini, RS, Brazil. The survey was conducted from September to January, 1977/78 and 1978/79 seasons. Fly traps 'Valenciano' type, containing molasses, peach juice and hydrolyzed protein were used as attractants. There was a difference in the population of Anastrepha sp. in the two years of study, with higher population dynamics in Pelotas and Piratini, 55% and 39,6%, respectively of the total captured (1.131) in 1977/78. In 1978/79, the greatest percentage was captured in Piratini, followed by Pelotas, 80.7% and 13.4%, respectively, of the total of 1,131. The lowest insect population was obtained in Canguçu, in view of insecticide application by the grower. Multiple linear regression analysis indicated a correlation in the number of insects captured in the three localities. In 1977/78, relative humidity and rainfall tended to influence population in Canguçu and maximum and minimum temperatures in Piratini. No correlation between the factors studied and insect population was obtained in Pelotas. In 1978/79, insect population was correlated to relative humidity in Canguçu and to maximum temperature and wind velocity in Pelotas. No correlation was, however, obtained in Piratini. The variation obtained as to the correlation of meteorological factors and number of insects captured in the different localities could be due to the following: a. The population of Anastrepha does not depend entirely on the climatic factors studied; b. Parallel observations suggested that availability of alternate hosts is the principal factor involved in the fluctuation and dinamics of population of Anastrepha in the localities surveyed; c. Anastrepha spp. was most abundant In mid to late ripening peach cultivars (canning peach).