Browsing by Subject "Neonicotinoid"

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    Chronic exposure of imidacloprid and clothianidin reduce queen survival, foraging and nectar storing in colonies of Bombus impatiens
    (2013-07) Scholer, Jamison D.
    The 20 year research focus on residue levels below 10 ppb of neonicotinyl insecticides found in nectar and pollen of seed-treated crops (corn, canola, and sunflower) has not demonstrated a reduction in bee colony health in most field studies. However, the label rate of neonicotinyl use on crops and landscape plants is much higher than seed treatments. In addition, crops and flowers can be retreated multiple times a season which can contribute to chronic exposure to bees at higher residue levels. In an 11 week greenhouse cage study with queenright colonies of Bombus impatiens Cresson, provided 0, 10, 20, 50 and 100 ppb imidacloprid or clothianidin in sugar syrup, neither neonicotinyl reduced production of brood, workers, and queens. Male production decreased in 10-100 ppb imidacloprid and 50-100 ppb clothianidin treatments. However, starting at 6 weeks queen mortality was significantly higher in 20-100 ppb imidacloprid or clothinaidin. The largest impact was the reduction in worker movement, consumption, number of syrup filled wax pots, and the addition of wax to the colony, which resulted in reduced colony weight. Queens and nest bees fed on the sugar syrup stored in wax pots that were filled prior to the start of the experiment. Foraging bees did not return sugar syrup to the nest, but remained on the floor of the flight box. We argue that queen mortality at 20, 50, and 100 ppb was related to lack of syrup in storage pots. We speculate that as queens started to die at week 6, workers in 20-100 ppb treatments produced fewer males and instead provisioned cells to produce new queens, since queen production was not reduced at higher doses, but male production was reduced. Since neonicotinyls in this and other studies were shown to reduce food consumption and foraging, wild bumblebee colonies that depend on workers to forage will be negatively affected by exposure to imidacloprid above 20 ppb. Solitary bees will be greatly impacted as the foraging queens solely provision the larvae.
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    Neonicotinoid and Fipronil Insecticides in Minnesota: A Statewide Survey into the Occurrence, Detection, and Removal of Neonicotinoids and Fiproles in Minnesota Surface Waters ,Groundwater, and Engineered Treatment Systems.
    (2023-10) Goedjen, Grant
    Neonicotinoids and fiproles have been used extensively in Minnesota agriculture for the last three decades. Their high mobility in water and longevity in aquatic systems makes them key candidates for transport in surface runoff and groundwater to contaminate Minnesota surface and groundwater systems. Four large field studies of (1) Minnesota groundwater and natural springs, (2) Minnesota surface waters, (3) stormwater and precipitation at stormwater-impacted Saint Paul Lake, and (4) wastewater, drinking water, and compost treatment systems were conducted over three years (2019-2022) to evaluate the state of neonicotinoids and insecticides in Minnesota’s natural waters and the current capacity for removal by existing treatment processes. Shallow unconfined groundwater and natural springs were more susceptible to contamination than deeper groundwater. Clothianidin (41% of springs, 14% of wells) was the most common insecticide detected followed by thiamethoxam (31% of springs, 12% of wells), imidacloprid (22% of springs, 10% of wells), thiacloprid (19% of springs, 2% of wells), acetamiprid (12% of springs, 14% of wells), and fipronil (19% of spring, 1% of wells). Groundwater depth also appeared to limit groundwater contamination to shallow systems with detections increasing with increasing urban land use and watershed imperviousness. Tritium/groundwater age, dissolved oxygen (DO), and total nitrite plus nitrate (total oxidized nitrogen), all correlated to noenicitinoid occurrence. Clothianidin (31% lakes, 60% rivers), thiamethoxam (19% lakes, 44% rivers), imidacloprid (65% lakes, 85% rivers), acetamiprid (29% lakes, 35% rivers), thiacloprid (15% lakes, 13% rivers), and fipronil (32% lakes, 30% rivers) were all detected in surface water lakes and rivers. Thiamethoxam and clothianidin has an association with agricultural watersheds while acetamiprid, thiacloprid, and fipronil were associated with urban watersheds. Increasing watershed catchment size and imperviousness increased the likelihood of contamination but the previous year’s application rates were the largest determining factor in the risk of insecticide contamination. All five neonicotinoid and fipronil were detected in stormwater (6% - 49%) and snow melt (13% - 29%). Stormwater and snow melt concentrations spiked with the “spring flush” during the early spring and summer months. Imidacloprid (17% rain, 47% snow), acetamiprid (6% rain, 33% snow), and clothianidin (44% rain, 39% snow), were all detected in direct rainfall and snowfall samples. Most of the contamination in stormwater (>76% stormwater, >67% snowmelt) was picked up as water moves through the watershed with correlated strongly correlations to application rates and soil and lipophilicity. Neonicotinoids and fipronil were present in drinking water, wastewater, and compost material provided by a commercial composting center. Current wastewater biological treatment technologies did not result in a significant reduction in concentrations. Biologically-activated carbon filtration with and without pre-oxidation provided a substantial reduction in concentrations (86% - 100% removal). Pre-oxidation did generate oxidized transformation products (<3.5% yield) but all transformation products were removed by downstream filtration. Compost was capable of degrading fipronil in both residential and commercial composting operations while clothianidin and acetamiprid were degradable in commercial composting systems and acetamiprid, clothianidin, imidacloprid, fipronil were partially degradable in residential composters. Runoff produced from rainfall at the composting facility with substantial neonicotinoid and fipronil concentrations.