Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
ENTOMOLOGY
Non Technical Summary
1. Two exotic pests threaten American beekeeping, parasitic Varroa mites and hive-scavenging small hive beetles. Both pests can be present in hives at the same time in the Southeast. 2. Chemical-limiting IPM practices rely on decision tools (economic thresholds) that help growers identify pest levels that warrant chemical treatment. A threshold permits a grower to practice non-chemical control methods as long as possible. 3. The PDs have developed economic thresholds for Varroa mite, but a similar value does not exist for the two-pest complex herein described. It is possible that the threshold for any one pest is lower when in the company of the other. A viable IPM program for this complex cannot get off the ground until an economic threshold is developed. 1. The purpose of this project is to develop a two-pest economic threshold for varroa mites and small hive beetles in honey bee hives. 2. Developing a threshold will lay the foundation for integrating
non-chemical controls in the management of these pests. For example, genetically resistant queen bees, screened hive bottoms, or beetle traps may slow pest population growth. But experience teaches that beekeepers must intervene with synthetic pesticides at some point. This threshold will identify the pest levels at which the beekeeper should intervene with a pesticide. 3. The larger goals of the project are to reduce beekeepers' reliance on chemical controls, reduce inputs of synthetic chemicals in the beekeeping industry, increase purity of hive products, and reduce chemical resistance in pest populations.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Goals / Objectives
The objective of the project is to develop an IPM economic threshold for a two-pest complex in honey bee colonies comprised of parasitic Varroa mites and hive-scavenging small hive beetles. Specifically, we aim to: 1. Determine a range of varroa mite and small hive beetle densities in honey bee colonies that are non-damaging, non-damaging but warranting treatment, and damaging, then 2. Determine a sampling protocol that reliably estimates colony populations of varroa and small hive beetles and corresponds them to levels determined in objective 1.
Project Methods
The design will be a split plot analysis of variance blocked on state (GA, SC) and replicated over two years. Within state, each whole plot will consist of one of five apiaries (6 colonies each) in which average colony SHB numbers will be manipulated to achieve 0, 150, 300, 600, or 1200 adults (600 was formerly determined to constitute an economic injury level). Within each whole plot (apiary), each colony will be randomly assigned one of three varroa miticide treatments (2 colonies per treatment) in order to experimentally vary varroa numbers: treatment with Apistan (fluvalinate) constantly beginning in June, once in August, or once in October; based on our earlier work we expect this procedure to yield average colony mite populations of 0, 3172, and 6662 by June, August, and October, respectfully. SHBs will be lab-reared (KSD's lab is fitted to do this), counted, and added to colonies in the appropriate apiaries soon after the April/May setup. Colonies will be
previously fitted with a SHB trap / sampling device. Beetles will be added to colonies at dusk, then beetle numbers in traps recovered the next morning at near dawn (ca. 12 hours). This procedure will minimize risk of confounding data with beetle dispersal, but we also plan at least one more sampling within 7 days of beetle release. This way we can appraise which sampling regimen most accurately predicts introduced beetle numbers: 12 hour, 7 day, or mean of the two. The relationship of beetle trap catches with actual beetle numbers introduced will be tested with regression analyses. At each sampling a number of live beetles equal to the amount of dead retrieved in traps will be re-introduced to colonies to restore experimental beetle densities. The resulting regression model will be used to predict actual colony beetle numbers in subsequent months. An attempt will be made to keep apiary SHB adult levels constant over the course of the study. Adult traps will not be activated except
for scheduled samplings, but the ground in front of all colonies will be treated with GardStar (permethrin) to kill wandering SHB larvae and limit local population increase. Beetle adults will be added if sampling indicates numbers have dropped below target levels. Once during each month of June, August, and October (before Apistan applications) we will sample each colony to determine colony strength parameters: number of adult bees, cm2 sealed brood, varroa mite levels on 24-h bottom board sticky sheets, and adult SHB levels. All colonies will be sampled again in December, and investigators will identify economic thresholds as the highest historic mite and SHB levels which failed to deviate colony condition in December from that of colonies with the historically lowest pest pressures (zero SHB added, constant Apistan treatment). Similarly, damaging pest levels will be identified as the historic mite and SHB levels which resulted by December in colony conditions significantly
deteriorated from the level deemed the economic threshold.