Foraging, spatial distribution and the effect of honeybees on soybean yield

Abstract

The soybean is the most cultivated grain crop in Brazil and there are many efforts to protect visitor pollinators, especially honeybees. The understanding of honeybee behavior on soybean fields is important to growers to apply integrated pest management strategies to avoid harm the pollinators. The European bee (Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae)) is a social bee, with European origin, whose the worker length is 12 mm to 13 mm with darker chest hairs. In this sense, foraging hours of Apis on soybean, its spatial distribution, the effect of pollination on soybean yield and the effect of insecticides on honeybee behavior were investigated. Two experiments were carried out. The first experiment was performed in a soybean field with 79 sampling points and four insecticide treatments to understand the spatial distribution of honeybees. In addition, foraging behavior of honeybees was evaluated hourly from 7:00am to 7:00pm randomly on 40 sampling points. The second experiment was carried out in cages with and without honeybees to quantify the effect of pollination on soybean yield under spray of chemical insecticides. Four hives with Africanized honeybees (A. mellifera) were set around the area. The hives had approximately six to eight brood frames and two to four food frames. Insecticides were sprayed as diferent treatments. The first experiment showed that honeybees prefer to forage on soybean flowers from 10:00am to 1:00pm and have random distribution. The use of A. mellifera as a pollinator did not increase the yield of soybean. Besides the particular manner of experiment’s conduction, the information of foraging behavior of honeybees, the pollination effect on soybeans yield and the effect of insecticides on honeybees are prudently discussed and some implication for soybean producers are also carefully addressed to avoid insecticide applications to harm pollinators. It is important to understand that the effect of pollination on yield of soybean depends on environmental conditions, cultivars, the effect of caging plants, and the abnormally high concentration of bees in the cages