Atividade de alguns insetos em flores de Brassica napus L. em Dourados-MS e a interação com fatores climáticos

Abstract

The objective of this work was to study the populational fluctuation, the preferred visiting time, and the interaction with climatic factors in several phenological stages from visitant insects in Brassica napus L. flowers. The study was accomplished in Dourados-MS, Brazil. The insects were collected with a 30-cm wide entomologic sweep net every 2 hours from 7h00 to 17h00. Apis mellifera L., 1758, Trigona sp., and Brachygastra lecheguana (Latreille - 1824) were gathered in B. napus flowers. A dipterous from the Chloropidae family was the insect with the largest populational density in the samples. The large occurrence of most pollinators was between 9h00 and 15h00, but Trigona sp. was present in larger numbers between 9h00 and 11h00. The largest frequency of pollinator insects occurred during stage III of flowering. The correlation analysis indicated that the relative humidity between 11h00 (r= 0,57) and 13h00 (r = 0,43) favored the occurrence of the dipterous from Chloropidae family. Populational reductions of pollinator insects, during stage III to stage IV of flowering, was probably due to lower temperatures, 16ºC.