Fatal powdering of bees in flight with particulates of neonicotinoids seed coating and humidity implication

Abstract

Losses of honeybees have been reported in Italy concurrent with the sowing of corn coated with neonicotinoids using a pneumatic drilling machine. Being unconvinced that solid particles containing systemic insecticide, falling on the vegetation surrounding the sown area, could poison bees foraging on contaminated nectar and pollen, the effect of direct aerial powdering was tested on foragers in free flight near the drilling machine. Bees were conditioned to visit a dispenser of sugar solution whilst a drilling machine was sowing corn along the flight path. Samples of bees were captured on the dispenser, caged and held in the laboratory. Chemical analysis showed some hundred nanograms of insecticide per bee. Nevertheless, caged bees, previously contaminated in flight, died only if kept in conditions of high humidity. After the sowing, an increase in bee mortality in front of the hives was also observed. Spring bee losses, which corresponded with the sowing of corn-coated seed, seemed to be related to the casual encountering of drilling machine during foraging flight across the ploughed fields

Scientific Opinion on the science behind the development of a risk assessment of Plant Protection Products on bees (Apis mellifera,Bombusspp. and solitary bees)

“…Although this concept can be considered as a first tier approach, a lot of information on all these aspects is still needed. Recent studies confirm the presence of high insecticide concentrations in dust particles emitted during sowing of treated corn seeds (Pistorius et al, 2009;Marzaro et al, 2011;Girolami et al, 2012). Small particles (PM10), in particular, are characterised by high atmospheric mobility and can be efficiently intercepted by flying bees.…”

“…Small particles (PM10), in particular, are characterised by high atmospheric mobility and can be efficiently intercepted by flying bees. Experimental determinations of total suspended matter (TSP) and PM10 concentrations at the field margin clearly indicated the presence of non-negligible levels of (even very small) particles (Tapparo et al, 2012). Even TSP values of up to 13.1 µg/m³ and PM10 values of 1.2 µg/m³ are observed at a distance of 10 m from the drilling machine during sowing of treated corn seed.…”

“…Even TSP values of up to 13.1 µg/m³ and PM10 values of 1.2 µg/m³ are observed at a distance of 10 m from the drilling machine during sowing of treated corn seed. Experimental matter emission measurements near the waste pipe of drilling machine during the sowing of treated corn seeds from 2009 and 2010 revealed emission of 0.46-1.53 g/ha, corresponding to 0.55-1.84 %, respectively, of the released amount of the active ingredient (Tapparo et al, 2012), although it should be recognised that the actual level of dust present was not reported and these data were generated prior to the Commission Directive on seed treatments. First tier values can eventually be compared with and replaced by experimental data.…”

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

“…It also has further benefits, such as pest population reductions, protects soil and water quality by mitigating runoff and soil erosion, and enhances rural aesthetics (Wratten et al 2012). Despite the benefit to pollinators feeding, the presence of agri-environmental schemes based on weeds poses a risk of insecticide exposure to bees foraging when the area is treated (Girolami et al 2012;Botias et al 2015). Therefore, the enhancement of floral resources for bees in agrosystems through the establishment of habitats containing flowering weeds must be accompanied by supplemental pesticide mitigation strategies.…”

Modulation of pesticide response in honeybees

“…Honeybee colonies, whose development and maintenance are intimately associated with environmental floral resources, can therefore be frequently exposed to multiple pesticide compounds that are recovered in pollen and nectar (Charvet et al 2004;Mullin et al 2010;Johnson 2015). Contaminated dust and water can also contribute to increase the risk of exposure (Girolami et al 2012;SamsonRobert et al 2014). While foraging, bees can be exposed to some pesticides, but acute exposure can become chronic after frequent foraging trips.…”