Agricultural intensification impairs behavioral abilities and the expression of genes associated with social responsiveness in honey bees

The honey bee Apis mellifera is one of the main pollinators in agroecosystems, and consequently, its colonies are exposed to agricultural intensification. These practices lead to increased use of agrochemicals, resulting in fragmented and more homogeneous habitats. In an agricultural setting located in the region of the Argentine Pampas, behavioral and molecular approaches were performed in honey bee colonies to compare their global state at different times of crop management. Our results show that foraging honey bees captured in these beehives impaired their gustatory sensitivity, cognitive abilities, and the brain’s expression of several genes related to metabolic, immune and neuronal processes associated with social behavior in bees after pesticide application and the flowering of the surrounding crops. To our knowledge, no previous study has reported the impaired effects of agricultural intensification on insect pollinators from an integrative neurobiological perspective under reali..., Methods
Colony activity
We evaluated as a colony activity indicator, the number of incoming bees (incoming rate) at the entrance of the hives at each sampling moment. In each apiary, we randomly chose eight hives. The same eight hives were measured in the two sampling moments. We counted the arrivals in the hives chosen for 1 min, twice a day for three consecutive days, once in the morning and once in the afternoon. According to the presence or absence of pollen loads on their hind legs, incoming bees were recorded as pollen or non-pollen (nectar) bees, respectively. Plot, Moment and year were taken as fixed variables, while hive was taken as a random variable in a Negative binomial model.
Pollen traps
Pollen traps were placed in three randomly selected hives (different from the eight hives used for colony activity) for about 6 h and for three consecutive days. The weight of pollen loads collected in each pollen trap was measured. Color-classified pollen loads of each trap were weighed ...,