The role of imidacloprid systemic insecticide on colony collapse disorder of honey bees and decline of bumble bee pollinators
Pollinators in general are experiencing serious decline and honey bee colonies are experiencing
conspicuously high mortality due to an event now called Colony Collapse Disorder (CCD). Systemic neonicotinyl insecticides, which replaced organophosphates, are considered as a factor in bee decline. Most of the research on the effects of neonicotinyl insecticides on honey bees focused on the translocation to nectar and pollen of Gaucho (imidacloprid) seed application. However, soil applications for crops and landscape plants use greater concentrations of imidacloprid applied closer to flowering. Gaucho seed application resulted in 1.9 ppb imidacloprid in sunflower nectar and 0.6 to 0.8 ppb in canola nectar. Soil applied imidacloprid was translocated to buckwheat nectar at 16 ppb and milkweed nectar at 41 ppb/flower (Marathon 1%G). These concentration of imidacloprid caused high mortality of beneficial insects, such as lady beetles, lacewings, and a small parasitic wasp. However, the effect on bees of these higher concentrations has not been studied.
In the field on canola we will use a seed and soil application to determine the amount of imdacloprid translocated to canola pollen.
We will perform long and short term studies on bees to determine the correlation between imidacloprid pollen residue and bee mortality.
We will work with beekeepers, state agencies, commodity groups, and growers to disseminate this research-based information on how to protect and promote bees. We will suggest alternative insecticides that are more bees friendly to be used in crops and landscapes that now use imidacloprid. Also, to lure bees from treated areas, we will develop lists of pollinator friendly plants to be used in natural resources management, such as conservation plantings, roadsides, and restoration.
Objective 1. Add imidacloprid insecticide(Admire) to the soil (seed treatment, 1x, 2x, 20x, 40x). Determine thru residue analysis how much imidacloprid is translocated to pollen of canola.
Objective 2. Determine the effects imidacloprid in sugar syrup on the behavior and survivorship of bumble bees in a greenhouse
Objective 3. Determine the effects imidacloprid in sugar syrup on the behavior and survivorship of honeybees on the St. Paul campus of the University of Minnesota.
Objective 1. Add imidacloprid insecticide (Admire) to the soil (seed treatment, 1x, 2x, 20x, 40x). Determine thru residue analysis how much imidacloprid is translocated to pollen of canola.
We investigated how much imidacloprid is translocated to canola anthers (pollen) from a soil treatment of imidacloprid (6 treatments: 0, seed treatment, 1x, 2x, 20x, 40x). Eventually with the data, we will plot application rates against flower residue to get a model for how much is translocated from soil to flowers for different plants.
In 2010, we planted 4 plots with canola on the St. Paul campus. The plot used in the first planting in April was replanted in June and sprayed. June plants collected imidacloprid from the soil (imidacloprid retained in soil from April plus imidacloprid from chopped plants turned into the soil from April). The June planting had the highest imidacloprid residues. Imidaclopird residues in treatments were: 0 ppb (C), 368 ppb (1x), 153 ppb (2x), 213 ppb (20x), and 3900 ppb (40x). The June plants developed faster, so when we sprayed the canopy was bigger. Perhaps imidacloprid on the soil surface was shaded and it was not degraded by light.
The July planting had no imidacloprid applied to the soil. However, residue was found in the July pollen in each treatment with increasing ppb: 0 ppb (C), 5 ppb (1x), 10 ppb (2x), 10 ppb (20x), and 140 ppb (40x). This was due to the imidacloprid application in the same field in May and the plowing of the May canola stalks into the field.
Objective 2. Determine the effects of imidacloprid in sugar syrup on the behavior and survivorship of bumble bees in a greenhouse
Behavioral observation of individual bees
We performed research on the effects of 3 neonicotinyl insecticides (imidacloprid, thiamethoxam, and clothianidin) on the LD50 of bumblebees at 10 microl and 50 microl. The LD50 is around 6ng/bee or 60 ppb which is in the range found in published papers. Now we have a reference that our lab experiments are similar to published studies.
Effects on imidacloprid on bumble bee learning
We found thru PERS experiments (proboscis extension refex) that 0.2 ng/bee or 2 ppb affects bumble bee memory.
Effects of imidacloprid on bumble bee health.
We have spent the last 12 months learning how to raise bumble bees in the greenhouse. We started colonies with overwintering females put in diapause in the incubator at 5C and revived with CO2 for 2-30 min exposures. We placed them in small bee boxes. Exp 1 with 100 females failed. The grower provided 100 more females and 1 month later 20% have started to lay eggs. We decided this is too long a period to maintain the colonies. Now we have made new bee boxes and will use Research A colonies (30 bumble bee worker's and queen) from Koppert. We will begin this study in June 2011.
Objective 3. Determine the effects of imidacloprid in sugar syrup on the behavior and survivorship of honeybees on the St. Paul campus of the University of Minnesota.
Measures of Colony Health
We fed sugar 50% syrup spiked with 5 concentrations of pesticides (0, 10 ppb imidacloprid, 100 ppb imidacloprid, 15 ppm Pristine fungicide, and 15 ppm Pristine fungicide + 10 ppb imidaclopird; n=6 colonies/treatment) from Aug 17 to Sept 17. Out of 10 parameters measured, only total foragers had fewer bees in the 200 ppb treatments. The other 9 parameters were not significantly different among treatments: FOB, area sealed brood, area open brood, area total brood, area pollen, brood pattern, dead bee count, Nosema, Varroa. However, Queen replacements were 5 times higher in 200 ppb treatments than controls.
Also, we caged small colonies of bees on 1x, 2x, 20x and 40x imidacloprid-treated canola plants. We found that honeybees in the 20x and 40x treatments did not store nectar or pollen and had less foragers.
Impacts and Contributions/Outcomes
Outreach talks and workshop
The PI gave 6 talks on the research in 2010 and the graduate student 3 talks:
Wild Ones Native Plant Society, Minneapolis; Fruit and Vegetables Conference, St. Cloud; MN Rose Society, Minneapolis; Anoka County Master Gardeners Meeting, Maplewood; MN State Fair Bee keepers, St. Paul; MN Honey Producers summer meeting, Waconia (2 talks), ND bee keepers, Annual American Beekeeping meeting.