- Fruits: berries (blueberries)
- Animals: bees
- Animal Production: animal protection and health
- Crop Production: food product quality/safety
- Education and Training: extension, farmer to farmer
- Farm Business Management: whole farm planning
- Natural Resources/Environment: wildlife
- Pest Management: chemical control
- Production Systems: organic agriculture
- Sustainable Communities: local and regional food systems, sustainability measures
Documented declines of native bumblebee populations have been recorded in Europe for the past six decades and have begun to be reported in North America. In contemporary times when the prices of rented honeybee hives are rising in the face of Colony Collapse Disorder (CCD), it is more important than ever to protect the native pollinators of our nation’s important crop systems. Although there is currently little consensus as to what is causing the bumblebee declines, there has been speculation about the possible role of systemic neonicotinoid insecticides in population losses. Here, I propose to investigate the effects of imidacloprid on a commercial bumblebee species that is native to North America, Bombus impatiens, by feeding colonies a range of field-realistic doses of imidacloprid and then following how those colonies perform throughout the season. Beyond this, I hope to establish an effective rearing protocol for a native species in Maine, B. ternarius, in order to use this species for such experiments in the future. In addition, the immune strength of individuals in each colony will be measured to quantify individual immunity and how it may change with exposure to different levels of imidacloprid. Finally, levels of conopid fly parasitism were previously found be 25% in foraging workers in Maine lowbush blueberry systems. Fields around Downeast Maine will be surveyed via collection of bumblebee workers to assess prevalence of conopid fly parasitism in each field and, through the use of GIS, whether certain field characteristics might be connected to high parasitoid populations.
Project objectives from proposal:
Objective 1. To dose colonies of commercial Bombus impatiens with a range of field-realistic doses of imidacloprid early in the season, and then monitor their development through the summer. Bees will be dosed under lab conditions through their feed for 14 days, and then placed into six different wild blueberry fields during bloom (mid May – mid June). Parasite and pathogen load would be recorded from worker samples taken throughout the season, as well as from the colony as a whole at the end of the season. Groups of replicates would be placed in various wild blueberry fields with a variety of management techniques from organic to commercial around Central and Downeast Maine in order to test for field effects.
Objective 2. To monitor levels of conopid fly parasitism in the commercially-raised dosed colonies, as well as in wild caught native bumblebees collected from 16 lowbush blueberry fields in order to identify potential field characteristics that support large conopid populations. Conopid flies are known to attack pollinators in temperate regions around the world, making them a global issue. Because infected bees live for a shorter period of time, it is possible that heavy conopid infestations can result in lowered colony growth and the reduced reproductive success of a colony.
Objective 3. To establish an effective rearing method for the native species Bombus ternarius in order to use native colonies in a similar experiment as in Objective 1. Spring queens would be captured in early spring (mid to late April) and kept at ideal conditions to induce them to begin to build colonies in captivity.
Objective 4. To measure the immunocompetence of the imidacloprid-challenged bees using measures of levels of phenoloxidase (PO) in bees collected before dosing, during dosing, directly after dosing, and at regular intervals throughout the season. PO is part of the bee’s constitutive immunity and is important in the invertebrate immune response. In the absence of infection, PO is stored as an inactive precursor (pro PO), which is then converted to PO once an infection has been detected. PO assays can be done on frozen specimens using the thorax of the bee, which is homogenized in phosphate buffered saline. Then, reactants are added and reactions are allowed to proceed in a microplate reader. Enzyme activity can be measured using the absorbance readings as the reaction proceeds.