POPULATION FLUCTUATION OF "LEPROSIS MITE" Brevipalpus phoenicis (GEIJSKES, 1939) (ACARI, TENUIPALPIDAE) IN CITRUS ORCHARDS OF THE WEST OF SANTA CATARINA

Abstract

The mite Brevipalpus phoenicis (Geijskes, 1939) (Acari, Tenuipalpidae) is the vector of the "citrus leprosis virus" which provokes damages on fruit, leaves and branches, reducing the production and compromising the trees. To study the environmental influente on the population fluctuation of th is pest in the Western region of the State of Santa Catarina, Brazil, two citrus orchard of "Valência" cultivar with six year old were evaluated every two weeks from 1997 to 2000. During the evaluations, the number of mites was counted on the surface of three fruits or branches portions from the internai part of the canopy of 20 trees of each orchard. Infestai ion of leprosis mite were observed during all the studied period, with lower populations during the cold months and with increasing infesta- tions at the end of winter and the beginning of spring. Higher popualtions of B. phoenicis were observed during the worm months. Correlation analyses between the number of observed mites and the monthly maximum (tma) and minimum mean temperatures, rainfall, percentage of air humidity, insolation and wind speed accused "r" values of 0.55; 0.48; -0.17; -0.20; 0.24 and -0.23, respectively. Third order polynomial regression analyses with "F" test and probability of 0.05 resulted the equation y = 1257.5 -195.2tma + 8.35tma 2 -0.11 tma3, with R2 = 0.44.