START: 01 JUL 2003 TERM: 30 JUN 2005 FY: 2004 GRANT YR: 2003
GRANT AMT: $142,255
INVESTIGATOR: Ostiguy, N. M.
PERFORMING INSTITUTION:
ENTOMOLOGY
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK, PENNSYLVANIA 16802
EFFICACY OF QUEEN REPLACEMENT FOR VARROA IPM
NON-TECHNICAL SUMMARY: The number of managed and feral honey bee colonies has declined due largely to the varroa mite, an external parasite of the honey bee, reducing significantly the number of bees available for pollination or honey production. This project will evaluate varroa control methods such that honey bee colonies will remain healthy and contamination of hive products from miticide use is minimized.
OBJECTIVES: This project has two objectives: 1) test the efficacy of delaying queen release or caging queens to reduce varroa levels in honey bee colonies and 2) test the efficacy of delaying queen release or queen caging with screen bottom boards to reduce varroa levels in honey bee colonies. Delaying the release of or caging of a queen temporarily stops bee brood production; this has the potential to reduce the number of mites as brood is necessary for mite reproduction. At the start of the first year colonies will be established and divided into equal size treatment groups. Shortly after the colonies have reached their summer population size, queens will be removed from three groups of colonies with one group having queen replaced using the standard method, the second group will have their queen remain caged for 10 days and the last group will undergo emergency queen replacement. In two other groups the existing queen will be caged for 15 or 21 days. Forty percent of mites found on the hive bottom are alive. Screen bottom boards can decrease the number of mites in a colony because mites are prevented from reattaching on a bee if a screen separates them from the bees. At the start of the second year screened bottom board will replace the standard hive bottom board. The two most successful queen replacement/confinement tactics determined from the previous year will be used during the second year of the study Combining brood interruption with screen bottom boards should lower mite levels in a colony such that pesticide application is unnecessary.
APPROACH: In the first year, colonies will be installed into Langstorth hive bodies in apiaries located in central Pennsylvania, Delaware and eastern shore Maryland. Colonies will be equalized to ensure similar colony size and mite levels. One week after colony size adjustment, natural varroa drops will be assessed. Following the assessment of mite levels, each colony will be randomly assigned to a treatment group and queen manipulations will be performed. Within each apiary, the queen manipulations will be completed on the same day. The colonies will be manipulated as follows: 1) no queens replaced or confined, 2) old queens removed, caged queen inserted and queen released 24 hours later, 3) old queen removed, caged queen inserted, queen released 10 days later, 4) queen removed, natural supercedure allowed to occur, 5) old queen confined for 15 days and 6) old queen confined for 21 day. On the first day of queen manipulation, natural varroa drop assessments will begin and continue until all queens have been released. Mite drop assessments will change to every 14 days and continue until the end of the season, approximately mid-October. A final varroa drop will be assessed using sticky boards following treatment by coumaphos. To monitor varroa populations, boards are smeared with petroleum jelly and placed beneath a screen insert, which prevents bees from removing debris, including mites, from the board. Boards remain in colonies for 3 days to provide an average mite drop per day. Acceptance by the colony of the queen confinement/replacement tactic will be assessed by recording frequency of aggressive behavior toward the queen, occurrence of new queen cells and replacement of queen by using a Likert scale. The number of new queen cells or replacement of queen will be recorded. Colony health will be assessed by counting the number of frames of bees, the degree of chalkbrood infection, and the presence of American Foulbrood. Honey production will be recorded. After year 1, any colonies that fail to overwinter will be replaced to bring the total number of colonies in each apiary to 28. In mid-June prior to queen manipulation in July, colonies in each apiary will be equalized to ensure similar colony size and similar mite levels. Colonies will be randomly assigned to treatments. Screen bottom boards and data loggers will be installed. One week after adjustment of colony size, natural varroa drops will be assessed in all colonies to determine if mite levels are equal in the colonies. Within each apiary, the queen manipulations will be completed on the same day. The queen manipulation will be chosen on the basis of the results of the Year 1 study. On the first day of queen manipulation, natural varroa drop assessments will begin and continue until all queens have been released. Mite drop assessments will change to every 14 days and continue until the end of the season, approximately mid-October. A final varroa drop will be assessed using sticky boards following treatment by coumaphos. Colony strength, health, honey production and overwintering will be assessed as described for year one.
PROGRESS: 2004/01 TO 2004/12
The objectives of this project are to test during the first year the efficacy
of delaying queen release or of queen caging as an IPM tactic to reduce varroa
levels in honey bee colonies and to evaluate during the second year the combined
efficacy of delaying queen release or of queen caging (determined from results
of the first year's experiment) with screen bottom boards to reduce varroa levels
in honey bee colonies. During the first year (2003), mite levels were extremely
low throughout the Mid-Atlantic region. Thus we were only able to determine
the impact of our interventions on colony health. Fortunately, no end of the
season differences in colony health or honey production were observed among
the treatments. Data from the second year (2004) indicate significant reductions
in the number of mites in colonies where the queen was caged for more than 10
days. No differences were observed between colonies that were requeened and
those colonies where the existing queen was caged. Data will be collected during
summer 2005 to determine the impact of queen caging for 10 days and screen bottom
boards on mite populations. Data on ambient conditions within the hive during
summer 2004 are still being analyzed to determine if differences in temperature
or humidity exist among treatments. The 2004 data will be compared to data collected
during summer 2005 to determine if screened bottom boards impact ambient conditions
within a hive.
IMPACT: 2004/01 TO 2004/12
Honey bees are essential to over 90 fruit and vegetable crops worldwide and
are valued at $14.6 billion in the US. Honey bees also pollinate many plants
that are integral components of ecosystems. The accessibility of managed colonies
of honey bees from beekeepers and the background pollination by wild colonies
have declined over the past ten years due largely to an external parasitic mite,
'Varroa destructor'. In PA, for example, an average of 53 percent of managed
honey bee colonies died between 1995 and 1996. In many regions of the US, nearly
all feral honey bee nests have died. The loss has been noticed by those who
have relied on feral bees for pollination, and has resulted in an increased
demand for managed honey bee colonies. The primary pesticides used to control
the mite are fluvalinate, a pyrethroid, and coumaphose, an organophosphate.
Mite resistance to fluvalinate is widespread, leading to colony collapse. Resistance
to coumaphos, used only since 1999, has been reported already. Both pesticides
have been detected in hive products, e.g., honey. These compounds are lipid
soluble so the quantity in honey will be less than the quantity in wax. Fluvalinate
in wax has been reported to cause adverse effects on exposed queens and drones.
Coumaphos has been shown to increase sublethal effects and to increase queen
mortality rates. Our project will provide beekeepers with the ability to reduce
mite numbers in their colonies without the use of pesticides. This should result
in healthier colonies, lower costs, and fewer residues in hive products.
PUBLICATIONS: 2004/01 TO 2004/12
No publications reported this period
PROJECT CONTACT:
Name: Nancy Ostiguy
Phone: 814-863-2872
Fax: 814-865-3048
Email: nxo3@psu.edu
URL: http://www.cas.psu.edu/