A honeybee IPM program for pollinator health in blueberry production

A honeybee IPM program for pollinator health in blueberry production

Summary

Monitored hives were set placed on 8 commercial blueberry farms during blueberry pollination. Data was collected by monitoring hive ejected dead bees (1 – 7 day count), percent brood coverage (2 counts), and pesticide residue analyses. Hives were marked for sampling (101 hives). A subset (16) was outfitted with new comb foundation and queens for pesticide residue analyses at the end of pollination. A total of 15 active ingredients were found in pollen and comb samples. One twilight meeting presentation was made to commercial blueberry growers in the spring, and two additional presentations are planned for January and February 2016 grower meetings.

Objectives/Performance Targets

During early April of 2015 we constructed 101 trays made of ¼” hardware cloth. These were made to count dead bees removed from the monitored hives as an estimate for field mortality. We also numbered 101 hives to be sampled throughout the pollination season. In preparation for the blueberry pollination season, we prepared 16 hives with new wax comb foundations, and marked each of these hives. These 16 hives were a subset of the 101 sampled hives, and served as the ‘pesticide monitoring hives’.  Hives were placed in commercial blueberry fields starting on April 26, 2015. A total of 1,548 hives were placed on 8 farms (sites). New comb hives were placed at the rate of 2 hives per site on 8 sites. Field kill estimates were taken with dead bee counts in the hardware cloth trays on May 8-9 (cleanup) and again on May 15-16 for a 7-day count. Brood coverage was measured on both sides of 3 frames: center, second from right, and second from left approximately 7 days after placement (5/7), and again 3 weeks later (5/29) just prior to hive removal from the fields. Both dead bee counts and brood coverage measurements were done on the101 numbered and marked sample hives. Brood coverage included open cells with live brood or eggs, and capped brood. Hives were noted as queened or queenless. Pollen and comb samples (5-6 gram) were taken from the subset of sample hives that had been outfitted with new comb foundations and queens at the start of the pollination season. Pollen samples were placed in glass vials and immediately frozen before being sent to a lab for pesticide residue analyses. Pollen samples were submitted to the National Science Laboratories in Gastonia, N.C. on September 3 and screened for pesticide residues of 174 active ingredients in ppb; method identified as MET-123. A presentation was made to commercial blueberry growers as the project started on April 23. Additional presentations are planned for commercial blueberry growers at the New Jersey Agricultural Convention on February 10, and the New Jersey Beekeepers Association on February 13, 2016.  

Accomplishments/Milestones

The 7 day dead bee count averaged 27.7 bees per hive and ranged from 0 to 114 dead bees per hive. Most hives had between 10 to 30 dead bees per hive. The percent brood coverage was averaged for all 6 comb counts per date, and sampled hives compared by date. The reading on the first date (5/7) was used as the base. Therefore hives should show an increase in brood coverage by the second date (5/29). By 5/29 59 hives out of 101 (58.4%) showed an increase in brood coverage. There was “0” growth or less coverage in 42 hives (41.6%). In the subset of 16 new comb hives12 of the 16 showed growth and 4 showed “0” growth or shrinkage. Analyses for pesticide residues showed up to 15 active ingredients were present in sampled hives. Some of these such as DMPF, Coumaphos and Fluvalinate were common and are attributable to the products used for Varroa mite control. Fungicide residues included Azoxystrobin, Fenbuconazole, Metalaxyl, Boscalid, Pyraclostrobin, Captan and the Captan metabolite, THPI. All of these are normally used in blueberries, including just before and during pollination. Other insecticide residues included Esfenvalerate, Imidacloprid, Phosmet, and Chlorpyrifos. Atrazine was found in 3 hives.

Impacts and Contributions/Outcomes

The data is currently being evaluated, and pesticide residues compared to site, brood coverage and queen presence. Grower pesticide use records are being collected from those growers where hives were placed, and those records will be compared with residues found. However, honey bees do not know the boundaries of the farms where they are placed and forage wherever suitable nectar and pollen is found. Two pesticide residues, Chlorpyrifos and Atrazine are not labeled in blueberries and could have been used on other crops within the foraging range of the bees. This area-wide issue of pesticide use and honey bee management needs to be further explored.  

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