Progress 11/01/99 to 11/01/03
Outputs
The project successfully completed a four-year initiative to develop sustainable honey bee IPM practices holistically framed in the context of honey production and crop pollination. Eleven refereed scientific papers are the tangible record of this productivity. Two exotic honey bee pests Ire our chief subjects: the blood-feeding parasitic mite Varroa destructor and hive scavenging small hive beetle (SHB) Aethina tumida. North America's first economic threshold for varroa is shown to be 60-190 mites in standard overnight sticky sheets, and genetically resistant queen bees and screened bottom boards are shown to significantly slow mite population growth and delay economic threshold. Small hive beetles are shown to be omnivorous, feeding on honey bee eggs as well as stored honey and pollen. In a comparative study between South Africa and Georgia it was shown that that average adult beetle numbers ranging from 409.3 plus or minus 95.8 to 589.3 plus or minus 150.3 Ire
sufficient to significantly reduce colony bee populations, brood, foraging activity (returning bees / min), and honey yields in European-derived honey bees in Georgia. A modified hive entrance - 1.5-inch PVC pipe - significantly reduces ingress of SHB adults into hives, but secondary ventilation problems are only partly overcome with screened bottoms. In a crop pollination syndrome only poorly understood, honey bees are shown unambiguously to linearly increase fruit-set in rabbiteye blueberry as bee flower visitation rates increase. Moreover, honey bees effectively set fruit in this crop even when they engage in high rates of secondary nectar thievery (they preferentially visit holes in flowers made by the primary nectar thief, Xylocopa virginica). Collectively these studies support the continued use of honey bees as commercial blueberry pollinators and suggest that current standard hive densities should be increased. One peripheral experiments demonstrate that honey yields are not
significantly increased in 'bottom supering' - a traditional practice in which empty honey boxes (supers) are placed on hives during nectar season below ones already partially filled by bees. Another peripheral study showed that colony brood production is significantly reduced in colonies housed on old combs. This is a powerful warrant for beekeepers to regularly cull old brood combs from their operations.
Impacts
Expected Impact: The benefits accruing to the Southeastern states from IPM practices growing from this project should over a five-season period translate to: 1. 1,023,400 fewer chemical applications for varroa control 2. 190,890 fewer chemical applications for SHB control 3. 719 kg reduction in the active ingredient fluvalinate (assuming it comprises 50% of varroa chemical treatments) 4. 1651 kg reduction in the active ingredient coumaphos (assuming it comprises 50% of varroa treatments and 100% [one strip only] for SHB) 5. 179 kg reduction in the active ingredient permethrin 6. $4,488,047 savings in chemical applications (16% of average 5-year honey revenues) 7. reduced risk of contaminated honey 8. reduced risk to the environment and handler 9. improved reproductive performance of queen bees produced in the region (in-hive chemicals reduce sperm loads of drones and longevity of queens) Concerning blueberry pollination, our data indicate that fruit-set increases 15%
over ambient conditions when pollinator densities are maximized. Although we have not extrapolated our controlled densities to actual hive field densities, I conservatively believe that increasing the current recommendation from 3 hives per acre to 5 would be economically viable. Based on 2002 NASS production data for Georgia I estimate that optimizing honey bee pollinator densities in blueberry translates to a revenue increase of $2,613,000. This value, combined with the chemical savings detailed above, result in a societal benefit of $7,101,047 from this project.
Publications
- Delaplane, K.S. 1999. Effects of the slatted rack on brood production and its distribution in the brood nest. American Bee Journal 139(6): 474-476
- Delaplane, K.S. & W.M. Hood. 1999. Economic threshold for Varroa jacobsoni Oud. in the southeastern USA. Apidologie 30: 383-395
- Elzen, P.J., J.R. Baxter, D. Westervelt, C. Randall, K.S. Delaplane, F.A. Eischen, L. Cutts, & W.T. Wilson. 1999. Field control and biology studies of a new pest species, Aethina tumida Murray (Coleoptera: Nitidulidae), attacking European honey bees in the Western Hemisphere. Apidologie 30: 361-366
- Berry, J.A. & K.S. Delaplane. 2000. Effects of top- versus bottom-supering on honey yield. American Bee Journal 140(5): 409-410
- Berry, J.A. & K.S. Delaplane. 2001. Effects of comb age on honey bee colony growth, brood survivorship, and adult mortality. Journal of Apicultural Research 40(1): 3-8
- Ellis, J.D., Jr., R. Hepburn, K.S. Delaplane, P. Neumann, & P.J. Elzen. 2003. The effects of adult small hive beetles, Aethina tumida (Coleoptera: Nitidulidae), on nests and foraging activity of Cape and European honey bees (Apis mellifera). Apidologie, 34: 399-408
- Dedej, S. & K.S. Delaplane. 2003. Honey bee (Hymenoptera: Apidae) pollination of rabbiteye blueberry Vaccinium ashei var. 'Climax' is pollinator density-dependent. Journal of Economic Entomology 96(4): 1215-1220
- Ellis, J.D., Jr., K.S. Delaplane, R. Hepburn, & P.J. Elzen. Efficacy of modified hive entrances and a bottom screen device for controlling Aethina tumida (Coleoptera: Nitidulidae) infestations in Apis mellifera (Hymenoptera: Apidae) colonies. Journal of Economic Entomology, in press August 2003
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Progress 01/01/02 to 12/31/02
Outputs
In 2002 the project made diverse and significant advances in the areas of honey bee management and integrated control of beekeeping pests. We demonstrated that restricted hive entrances (with 1.5-inch pvc pipe) reduced the infestation rate of adult small hive beetles, but it was necessary to offset the lost hive ventilation with screen hive floors. Work at our lab demonstrated that small hive beetles oviposit in capped cells of honey bee brood at the terminal stages of beetle-induced colony collapse. Collaborative work between our lab and Rhodes University (S. Africa) demonstrated that adult small hive beetles are sufficient to cause significant harmful effects on colonies of European, but not Cape, honey bees. A separate study was continued on IPM practices that delay onset of economic threshold for varroa mites in honey bee colonies. Apiary isolation, hygienic-selected queens, and screen bottom boards failed to delay economic threshold for V. destructor. However,
the pooled data for 14 months support earlier evidence that bottom screens reduce colony mite levels. Moreover, hygienic behavior significantly reduced average mite drop, but its expression varied independently of the reported selection status of the queens. Finally, rabbiteye blueberry var. 'Climax' was shown to respond favorably to increases in density of honey bee pollinators.
Impacts
This research confirms small hive beetles as serious scavengers of weakened honey bee colonies and demonstrates a simple and effective practice for reducing their numbers - hive entrance reduction. Similarly, our project has demonstrated that screen bottom boards reduce varroa mites in bee colonies. Both of these hive modifications are being put into practice by beekeepers. In fact, screen bottom boards are already being marketed by bee supply manufacturers, a situation prompted in part by work from this lab. Our research confirms honey bees as valuable pollinators of rabbiteye blueberry, supporting the use of this practical pollinator wherever these popular blueberries are grown.
Publications
- Ellis, J.D., Jr., K.S. Delaplane, H.R. Hepburn, & P.J. Elzen. 2002. Controlling small hive beetles (Aethina tumida Murray) in honey bee (Apis mellifera) colonies using a modified hive entrance. American Bee Journal 142(4): 288-290
- Ellis, J.D., Jr., K.S. Delaplane, & W.M. Hood. 2002. Small hive beetle (Aethina tumida Murray) weight, gross biometry, and sex proportion at three locations in the Southeastern United States. American Bee Journal 142(7): 520-522
- Dedej, S., K.S. Delaplane, & H. Scherm. 2002. Effectiveness of honey bees in pollinating rabbiteye blueberry and in delivering the biocontrol agent Bacillus subtilis to control mummy berry disease. In Proceedings of the Georgia Blueberry Conference 2002: 13-23
- Delaplane, K.S. & J.D. Ellis, Jr. 2002. The small hive beetle (Aethina tumida) in the United States: Reduced hive entrances are a promising IPM strategy. In Proceedings of 6th European Bee Conference, Cardiff, Wales, in press
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Progress 01/01/01 to 12/31/01
Outputs
A study was begun for testing the efficacy of various published IPM practices in delaying onset of the economic thresholds for varroa mites developed for the Southeast by Delaplane & Hood (J. Apic. Res. 36:125-132, Apidologie 30: 383-395). The IPM methods under investigation are colony isolation, hygienic queens, and hive bottom screens. Data from 2001-early 2002 suggest that the strongest benefit is realized by hygienic queens and bottom screens. Unexpectedly, mite drops tended to be highest in isolated apiaries. A 2001 field study examined the pollination efficacy and interactions of honey bees and nectar-thieving carpenter bees, Xylocopa virginica. When the numbers of Xylocopa tented with honey bees and blueberry plants increased from one to two, there were significant reductions in the average number of seeds, speed of ripening, and weight of berries. However, increasing the number of Xylcopa from one to two also increased fruit-set. At this point it appears that
carpenter bees contribute to blueberry fruit-set, but their net effects are negative. A study was conducted to test whether colony invasion by adult small hive beetles can be reduced by replacing the regular entrance of a hive with a 3/4-inch (2-cm) PVC pipe located 3-4 inches (7.6-10.2 cm) above the bottom board. Colonies with pipe entrances had significantly fewer adult beetles (46.9 beetles / colony) than open colonies (107.7 beetles / colony). However, there was a tendency for reduced brood in colonies with pipes. This experiment shows that modifying a colony's entrance may help control small hive beetles, but more work is needed to offset unwanted effects of reduced colony entrances.
Impacts
It is expected that the project will demonstrate practical ways to combat two serious honey bee enemies - the varroa mite and small hive beetle - with practices that minimize hard chemicals and improve profitability of beekeeping. Additionally, the project is demonstrating the value of honey bees as pollinators of rabbiteye blueberry, an important commercial crop in the Southeast.
Publications
- Webster, T.C. & K.S. Delaplane (editors). 2001. Mites of the honey bee. Dadant & Sons, Hamilton, Illinois, 280 pp.
- Hood, W.M. & K.S. Delaplane. 2001. Treatment thresholds for Varroa. In Mites of the honey bee. (T.C. Webster & K.S. Delaplane, eds.). Dadant & Sons, Hamilton, Illinois, pp. 229-239
- Ellis, J.D., Jr., K.S. Delaplane, & W.M. Hood. 2001. Efficacy of a bottom screen device, Apistan, and Apilife VAR in controlling Varroa destructor. American Bee Journal 141(11): 813-816
- Ellis, J.D., Jr. & K.S. Delaplane. 2001. A scientific note on Apis mellifera brood attractiveness to Varroa destructor (Anderson & Trueman) as affected by the chemotherapeutic history of the brood. Apidologie 32: 603-604
- Delaplane, K.S. 2001. Varroa destructor: Revolution in the making. Bee World (in press)
- Delaplane, K.S. & S. Dedej. 2001. Pollination of blueberry (Vaccinium ashei) by honey bees (Apis mellifera) and nectar-thieving carpenter bees (Xylocopa virginica). In Proceedings of Apimondia Congress, Durban, South Africa. pp. 133-147
- Delaplane, K.S. 2001. Progress report: Integrating mite mitigation measures with published economic thresholds for Varroa destructor. In Proceedings of the American Bee Research Conference. American Bee Journal 141(12): 888
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Progress 01/01/00 to 12/31/00
Outputs
It was determined that gross biometry of small hive beetle adults varies in three populations of the Southeast: Wadmalaw Island and Clemson, SC and Richmond Hill, GA. Adult females are significantly longer than males, but width does not vary by sex. This implies that the package bee industry could benefit by standardizing the screen diameter of its cages , effectively excluding the beetles. Wadmalaw Island beetles weigh significantly more than beetles in the other populations which is congruent with mitochondrial DNA from other studies. The screened bottom board was shown to numerically decrease colony populations of varroa mites and numerically increase brood production.
Impacts
Our data will help characterize populations of exotic small beetle in the Southeast and indicate methods for effectively excluding this pest from mail-order bee packages. The bottom screen appears to be an effective cultural control for parasitic varroa mites.
Publications
- Ellis, J.D., Jr., K.S. Delaplane, & W.M. Hood. 2001. Efficacy of a bottom screen device, Apistan, and Apilife VAR in controlling Varroa populations in honey bee colonies. ms in prep
- Ellis, J.D., Jr., K.S. Delaplane, & W.M. Hood. 2001. A scientific note on small hive beetle (Aethina tumida Murray) weight, gross biometry and sex proportion at three locations in the southeastern United States. Journal of Apicultural Research, submitted December 15, 2000
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