Sublethal concentrations of clothianidin affect honey bee colony growth and hive CO2 concentration

Abstract

The effects of agricultural pesticide exposure upon honey bee colonies is of increasing interest to beekeepers and researchers, and the impact of neonicotinoid pesticides in particular has come under intense scrutiny. To explore potential colony-level effects of a neonicotinoid pesticide at field-relevant concentrations, honey bee colonies were fed 5- and 20-ppb concentrations of clothianidin in sugar syrup while control colonies were fed unadulterated syrup. Two experiments were conducted in successive years at the same site in southern Arizona, and one in the high rainfall environment of Mississippi. Across all three experiments, adult bee masses were about 21% lower among colonies fed 20-ppb clothianidin than the untreated control group, but no effects of treatment on brood production were observed. Average daily hive weight losses per day in the 5-ppb clothianidin colonies were about 39% lower post-treatment than in the 20-ppb clothianidin colonies, indicating lower consumption and/or better foraging, but the dry weights of newly-emerged adult bees were on average 6–7% lower in the 5-ppb group compared to the other groups, suggesting a nutritional problem in the 5-ppb group. Internal hive CO2 concentration was higher on average in colonies fed 20-ppb clothianidin, which could have resulted from greater CO2 production and/or reduced ventilating activity. Hive temperature average and daily variability were not affected by clothianidin exposure but did differ significantly among trials. Clothianidin was found to be, like imidacloprid, highly stable in honey in the hive environment over several months.

A Monitoring System for Carbon Dioxide in Honeybee Hives: An Indicator of Colony Health

“…This is not unexpected as the queen excluder sensor is mounted close to the bulk of the colony. The change between night and day is consistent with previous recent reported values [ 10 , 15 , 16 , 17 ] and these changes in CO 2 are similar, if not in absolute values, in both sensor locations.…”

“…Higher levels in the hive are also believed to initiate fanning behavior. Recent advances in reducing the size of nondispersive infrared measuring devices have resulted in the start of in-hive CO 2 measurements [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Whilst oxygen is clearly important to honeybees, hypoxia is usually tracked indirectly by the measurement of carbon dioxide.…”

Honeybees control the gas permeability of brood and honey cappings

“…Honeybees can tolerate a wide range of CO 2 concentrations and the CO 2 levels in the hive are maintained well above the 0.04% found in the free atmosphere. The usual CO 2 concentrations in a beehive in summer fluctuate between 0.1 and 0.3% 42 , 43 but up to 4% CO 2 has been measured in small experimental hives in laboratory settings. 44 , 45 Based on our data, the brood cappings are highly penetrable to CO 2 .…”

Traces of a neonicotinoid pesticide stimulates activity in honey bee colonies, but not productivity

“…The 2014 experiment 16 and 2016 experiment 17 have been described previously and were conducted at apiaries in the Santa Rita Experimental Range (31°46'39"N, 110°51'46"W). The 2017, 2018 and 2019 experiments were conducted <1 km north of the 2014 site; data for the control treatment in the 2017 and 2018 studies have also been described previously 45 . The apiaries were surrounded by native mesquites (Prosopis spp.…”