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Research Archives

 

1. Drone production by young versus old worker honeybees in queenless colonies. Delaplane, K.S., & J.R. Harbo. 1987. Apidologie 18(2): 115-120

SUMMARY Drone production between 2 groups of worker honeybees (Apis mellifera L.) was compared in Baton Rouge, Louisiana : an older heterogeneous population of bees (> 54 days old at beginning of egg laying period), and a smaller group of young bees (11-15 days old). Six of 9 broodless, queenless colonies (providing the " old " bees) were each given 150 young bees that were heterozygous for visible mutations. The remaining 3 colonies were controls. Young workers produced a much higher proportion of drones in 3 of 6 the test colonies than did the old workers. Old workers produced at least as many drones per bee as did the young workers in the other 3 test colonies. Workers > 54 days old produced eggs in all colonies.

 

 

2. Effect of queenlessness on worker survival, honey gain, and defence behaviour in honeybees. Delaplane, K.S., & J.P. Harbo. 1987. Journal of Apicultural Research 26(1): 37-42

SUMMARY The effects of queenlessness on worker honeybees (Apis mellifera) were tested with 50 colonies in groups of 10 (five treatments and two replicates) in August, October and December, 1984 and February and April, 1985 in Baton Rouge, Louisiana. The 10 colonies in each group were all from a single heterogeneous mixture of bees, and each colony began with about 6000 workers and no brood. The five treatments each lasted for 28 days and consisted of (1) caged queen for 28 days, queenless for 0 days; (2) caged queen for 21 days, queenless for 7 days; (3) caged queen for 14 days, queenless for 14 days; (4) caged queen for 7 days, queenless for 21 days and (5) caged queen for 9 days, laying queen for 19 days (control). With prolonged queenlessness worker survival, colony weight gain and defence behaviour (number of stings) decreased. Queenlessness did not induce drifting.

 

 

3. A re-examination of double grafting. Delaplane, K.S., & J.R. Harbo. 1988. American Bee Journal 128(6): 439-440

ABSTRACT Double grafting did not produce heavier queens than did single grafting. If weight is a good indicator of queen quality, this study shows that double grafting is not worth the extra effort. Additionally, priming of cell cups before grafting into them did not improve weight of queens, but it did improve cell acceptance in nurse colonies.

 

 

4. Survey of miticide use in Georgia honey bee hives. Delaplane, K.S. 1992. American Bee Journal 132(3): 185-187

ABSTRACT In 1990, an estimated 32,007 Georgia bee hives were treated with menthol to control tracheal mites, and 20,771 hives were treated with Apistan® to control Varroa mites. In 1990, Georgia beekeepers spent at least $122,343 on miticides. If Georgia beekeepers had to rely solely on non-chemical controls against mites, they predict state-wide losses of hives and hive products of at least $5,748,091. Survey respondents represented 51,608 bee hives which are 46.5% of the hives in Georgia at the end of 1990.

 

5. Controlling tracheal mites (Acari: Tarsonemidae) in colonies of honey bees (Hymenoptera: Apidae) with vegetable oil and menthol. Delaplane, K.S. 1992. Journal of Economic Entomology 85(6): 2118-2124

ABSTRACT The efficacy of vegetable oil and menthol was tested in controlling tracheal mites (Acarapis woodi [Rennie]) in honey bees (Apis mellifera L.). Each of 40 bee colonies was given one of four treatments: (1) vegetable oil, (2) menthol, (3) vegetable oil and menthol, or (4) no treatment (control). Colonies were sampled for percentage bees infested and severity of infestation per infested bee on nine dates from 14 February to 7 August 1991. Treatments were applied on 27 February and removed on 18 April. On 3 April, mite infestation was reduced in the oil + menthol treatment. On every sampling date after 3 April, infestation was reduced by all oil or menthol treatments. Compared with menthol, vegetable oil gave equivalent mite control on all sampling dates. From 3 April through 9 May, infestation was lowest in the oil + menthol treatment. Except for one sampling date, severity of infestation per infested bee was unaffected by treatments.

 

6. Effects of Terramycin™ antibiotic and Apistan™ acaricide on colonies of honey bees (Hymenoptera: Apidae) infested by Varroa jacobsoni Oudemans (Parasitiformes: Varroidae). Delaplane, K.S. 1995. Journal of Economic Entomology 88(5): 1206-1210

ABSTRACT The effects of the antibiotic Terramycin and the acaricide Apistan were tested on colonies of honey bees, Apis mellifera L., infested with the parasitic mite Varroa jacobsoni Oudemans. Interest in antibiotics stems from the possibility that V. jacobsoni vectors pathogens. Each of 20 colonies randomly received 1 of 4 treatments: (1) 7 applications (28.3 g, 198.1 g total) of a standard Terramycin and powdered sucrose mixture, (2) 2 Apistan strips, (3) Terramycin and Apistan or (4) no treatment as an experimental control. Terramycin increased the body weight of hive bees of mixed ages and of newly emerged adult bees. Apistan increased the body weight of hive bees of mixed ages, maintained colony population size during a period of apiary-wide decline, decreased the number of V. jacobsoni per newly emerged bee, and decreased the incidence of misshapen newly emerged bees. Overall, the effects of Terramycin antibiotic and Apistan acaricide on V. jacobsoni-infested colonies were favorable or neutral, and no interactions between the 2 products were detected.


 

7. Bee foragers and their pollen loads in south Georgia rabbiteye blueberry Delaplane, K.S. 1995. In Proceedings of the American Bee Research Conference. American Bee Journal 135(12): 825-826

Rabbiteye blueberry (Vaccinium ashei Reade) is an important crop in parts of the southeastern United States. Habropoda laboriosa (F.) is the most efficient bee pollinator of rabbiteye blueberry, followed by bumble bee (mostly Bombus impatiens Cresson) queens; fruit set following single visits by honey bees (Apis mellifera L.) is reportedly no higher than that in flowers from which bees are excluded (Cane, J.H. & J.A. Payne, Alabama Agric. Exp. Sta. 37:4). Carpenter bees (Xylocopa spp.) rob V. ashei by slitting the corolla to suck nectar, completely bypassing the sexual column. Honey bees that visit flowers slit by Xylocopa spp. usually visit the robbery holes and, likewise, avoid the sexual column.

Although individual honey bees are inefficient pollinators of rabbiteye blueberry, they are ubiquitous and abundant in orchards. On the other hand, the more efficient bumble bees and H. laboriosa can be locally abundant or rare (Cane, J.H. & L.A. Payne, Ann. Entomol. Soc. Am. 86:577-588). Thus, questions remain about the practical pollination efficacy of bees visiting rabbiteye blueberry.

On 21, 27, 28, and 29 March 1995, I surveyed bee foragers on rabbiteye blueberry in four orchards in Clinch County, Georgia. With a handheld audio recorder, I walked between rows of V. ashei, and for every bee I saw on a flower, I recorded its genus and its behavior robbing, probing for nectar, carrying pollen on its corbiculae). Every sampling episode (n=12) lasted 30 minutes. I collected voucher bee specimens and later identified them in the laboratory. I collected bees on flowers individually in clean glass vials, washed each bee in 0.5 ml distilled water, agitated the bee and water with a vortex shaker for 30 sec, examined the suspended pollen microscopically with a cell counting chamber, and compared percentage Vaccinium pollen carried by different bee taxa, by robbing bees, and by bees visiting flowers legitimately.

Apis mellifera was the most numerous bee forager in rabbiteye blueberry, followed in order by B. impatiens queens, B. impatiens workers, X. micans. X. virginica, and H. laboriosa. Percentage pollen foragers was highest with B. impatiens workers (76.3 %), followed by H. laboriosa (60%), B. impatiens queens (38%), A. mellifera (3.2%), and X. micans (1%). Percentage robbers was highest with both Xylocopa species (100%), followed by A. mellifera (93.2%), H. laboriosa (13.3%), B. impatiens workers (2.2 %), and B. impatiens queens (0%). On average, percentage Vaccinium pollen on bodies of bees was highest with B. impatiens queens and workers (70.2 ± 34.7%), followed by A. mellifera (67.7 ± 43.1%), H. laboriosa (58.1 ± 27.5%), and X. virginica (29.5 ± 38.1%). Percentage Vaccinium pollen on bodies of bees was higher with legitimate flower foragers (77.7 ± 29.6%) than with robbers (47 ± 42.9%).

 


8. Effects of delayed acaricide treatment in honey bee colonies parasitized by Varroa jacobsoni and a late-season treatment threshold for the south-eastern USA. Delaplane, K.S. & W.M. Hood. 1997. Journal of Apicultural Research 36(3/4): 125-132

SUMMARY We set up 72 colonies of honey bees (Apis mellifera) in the piedmont region of Georgia and South Carolina, USA (2 states x 6 apiaries per state x 6 colonies per apiary) in April 1995. Colonies were individually housed in single-chamber Langstroth hive bodies and one honey super, started with standard mail-order 0.9 kg (2 lb) packages of bees containing small incipient populations of the parasitic mite Varroa jacobsoni, and managed optimally as for honey production. Within each state, each apiary was assigned one of the following treatments: (1) treatment with Apistan acaricide in June, (2) treatment in August, (3) treatment in October, or (4) no treatment. By December, colony bee populations were optimum in August-treated apiaries. Month of treatment did not affect bee body weight. There were treatment by state interactions for number of sealed brood cells, colony mite populations, and percentage of brood cells with disease-like symptoms. Our data suggest that late-season acaricide treatments in first-year colonies in the south-eastern USA piedmont are justified at colony mite populations of 3172 ± 324, 300-bee ether roll mite levels of 15 ± 1.4, and overnight adhesive bottom board insert mite levels of 117 ± 15 in colonies with 24 808 ± 2245 bees and 1825 ± 327 cm2 sealed brood; these conditions occurred in mid-August. Acaricide treatments in or before August may eliminate mite-associated brood pathology in the south-eastern USA. Bottom board inserts were more reliable predictors of colony mite populations compared to the ether roll method.

 


 

 

9. Effects of the slatted rack on brood production and its distribution in the brood nest. Delaplane, K.S. 1999. American Bee Journal 139(6): 474-476

Abstract In newly-installed package colonies, the slatted rack significantly increased the proportion of colony brood being reared near hive entrances, but did not affect overall quantity of brood produced. The experiment was replicated over three years.

 

 

 

 

10. Economic threshold for Varroa jacobsoni in the southeastern USA. Delaplane, K.S. & W.M. Hood. 1999. Apidologie 30: 383-395

ABSTRACT This research was designed to determine economic thresholds for Varroa jacobsoni mites in mature overwintered colonies under conditions that encourage or discourage mite immigration. Congruent data from the present study and our earlier work suggest that a true late-season (August) economic threshold for mites in the southeastern USA lies within a range of mite populations of 3 172-4 261, ether roll mite levels of 15-38, and overnight bottom board insert mite levels of 59-187 in colonies with bee populations of 24 808-33 699. Overwintering colonies can benefit from an additional early-season (February) treatment. This benefit was realized in colonies which in February had the following average values: mite populations 7-97, ether roll 0.4-2.8, bottom board inserts 0.6-10.2 and bee populations 12 606-13 500. Continuous acaricide treatment never achieved colony bee populations or brood number significantly higher than in colonies treated more conservatively. There is evidence that minimizing mite immigration has the benefit of delaying the onset of economic thresholds.

 

 

11. Field control and biology studies of a new pest species, Aethina tumida Murray (Coleoptera: Nitidulidae), attacking European honey bees in the Western Hemisphere. Elzen, P.J., J.R. Baxter, D. Westervelt, C. Randall, K.S. Delaplane, F.A. Eischen, L. Cutts, & W.T. Wilson. 1999. Apidologie 30: 361-366

ABSTRACT The small hive beetle, Aethina tumida Murray, is a nitidulid species newly recorded attacking honey bees in the Western Hemisphere. We initiated field and laboratory tests on the control and biology of this new pest. Very high mortality of adult and larval A. tumida in Florida and Georgia hives resulted from field tests using 10 % coumaphos in plastic strips in trapping devices on the hive bottom: as high as 90.2 % beetle mortality occurred in hives in Florida. Adult beetles were found in the laboratory to feed on honey bee eggs, completely consuming all eggs, even in the presence of honey and pollen. Odors from hive products plus adult bees were found to be significantly attractive to flying adult beetles, as evidenced in baited trap studies. Hive products alone or bees alone were not attractive to adult A. tumida.

 


12. Effects of hygienic queens, comb age, and colony microclimate on expression of chalkbrood disease symptoms. Dedej, S. & K.S. Delaplane. 2000. In Proceedings of the American Bee Research Conference. American Bee Journal 140(11): 903-904

Hygienic behavior in selected queen lines has been shown to reduce the incidence of chalkbrood disease symptoms (Spivak et al. 1998 Apidologie 29: 291-302). Nelson et al. (1982 Am. Bee J. 122: 29-33) showed that chalkbrood may be reduced in colonies housed on new comb. Laboratory evidence indicates that chalkbrood symptoms may increase under conditions of elevated relative humidity (Flores et al. 1996 Apidologie 27: 185-192).

We were interested in testing the interactive effects of hygienic queens, comb age, and colony microclimate on the expression of chalkbrood symptoms. Forty-eight colonies were set up; 24 were assigned high interior relative humidity (60.5 ± 1.7% RH and 24 were assigned low relative humidity (58.1 ± 0.6%). These differences were achieved by inserting a sheet of plastic between the inner and outer covers of each high humidity colony. Each colony within humidity class was assigned one of the following treatments: (1) new comb/non-hygienic queen, (2) new comb/hygienic, (3) old comb/non-hygienic, and (4) old comb/hygienic. Each colony was inoculated with the disease. For each of days 14, 21, 28, and 49, we determined for each colony the number of sealed brood cells and sum of chalkbrood cadavers.

High variances and missing values resulting from superseded queens prevented any significant differences. On average, brood production was consistently highest in colonies with low humidity, old combs, and (except for day 14) hygienic queens. The number of chalkbrood cadavers did not vary meaningfully according to humidity. Except for day 14, the number of chalkbrood cadavers was consistently lowest in colonies with old combs and hygienic queens.
 
 

13. Effects of top- versus bottom-supering on honey yield. Berry, J.A. & K.S. Delaplane. 2000. American Bee Journal 140(5): 409-410  PDF file

SUMMARY Bottom-supering failed to achieve significantly higher honey yields than the less labor-intensive method of top-supering. The experiment was replicated across three apiaries and two nectar flows.

 

 

 

 

14. A technical and economic evaluation of
beekeeping in Albania. Dedej, S., K.S. Delaplane &
E. Gocaj. 2000. Bee World 81(2): 87-97

INTRODUCTION Albania, a Mediterranean country with a hybrid population of Apis mellifera carnica and Apis mellifera macedonia, highly adaptable to its favorable conditions, has good opportunities and prospects for developing beekeeping. Albanian beekeepers have a long tradition in this activity.

 

 

 

 

15. Effects of comb age on honey bee colony growth and brood survivorship. Berry, J.A. & K.S. Delaplane. 2001. Journal of Apicultural Research 40(1): 3-8  PDF file


SUMMARY This research examined the effects of comb age on honey bee colony growth and brood survivorship. Experimental old combs were of an unknown age, but were dark and heavy as typical of combs one or more years old. New combs were produced just prior to the beginning of the experiment and had never had brood previously reared in them. Either old or new combs were installed into each of 21-24 nucleus colonies each year over a three-year period. On average, colonies with new comb produced a greater area (cm2) of brood, a greater area (cm2) of sealed brood, and a higher weight of individual young bees (mg). Brood survivorship was the only variable significantly higher in old comb.

 

 

16. A scientific note on Apis mellifera brood attractiveness to Varroa destructor as affected by the chemotherapeutic history of the brood. Ellis, J.D., Jr. & K.S. Delaplane. 2001. Apidologie, 32: 603-604   PDF file

Our results suggest that the degree of varroa mite attraction toward honey bee brood is relatively unaffected by the chemotherapeutic history of the brood and by variation in brood genetic homogeneity within a range found with non-selected queens either open-mated or single drone-inseminated. If the attraction of brood is useful as a selection criterion for breeding programs, our data suggest that the chemotherapeutic history of brood is a negligible source of environmental variation, but that some time (trial) effects may be expected.

 

 

17. Efficacy of a bottom screen device, ApistanJ , and ApilifeVARJ in controlling Varroa destructor . Ellis, James D., Jr., Keith S. Delaplane, & W.Michael Hood. 2001. American Bee Journal 141(11): 813-816
PDF file

ABSTRACT This study tested the efficacy of a hive bottom screen device in controlling varroa mites, when used alone or in conjunction with the miticides ApistanJ and ApilifeVARJ. Thirty six colonies were equalized and each assigned to one of six treatments: (1) no treatment, (2) bottom screen, (3) Apistan, (4) Apistan + screen, (5) Apilife, and (6) Apilife + screen. Adult bee populations were not affected by treatment, but the number of brood cells was significantly reduced in colonies treated exclusively with Apilife compared to that of colonies treated with Apistan or exclusively with a bottom screen. Brood production was numerically highest in colonies treated exclusively with a bottom screen. Varroa populations were significantly reduced in colonies receiving acaricide compared to non-treated colonies. Varroa populations in colonies treated exclusively with a bottom screen were 14.9 % lower than that of non-treated colonies, but this difference was not significant. The bottom screen did not affect the percentage of varroa mite population phoretic on adult bees. Apistan provided 100% mite control in South Carolina whereas in Georgia it provided 0% control in colonies treated exclusively with Apistan. With the addition of a bottom screen, Apistan-treated colonies in Georgia experienced an average mite control of 44.3%. This suggests that fluvalinate resistance exists in Georgia varroa mites. It also indicates that a bottom screen may help compensate for reduced acaricide efficacy. Average efficacy of Apilife ranged from 65.2 - 97.1%.

 

 

18. Controlling small hive beetles (Aethina tumida Murray) in honey bee (Apis mellifera) colonies using a modified hive entrance. Ellis, James D., Jr., Keith S. Delaplane, H. Randall Hepburn, & Patti J. Elzen. 2002. American Bee Journal 142(4): 288-290

ABSTRACT This study was designed to test whether colony invasion by adult small hive beetles can be reduced by replacing the regular entrance of a hive with a ¾-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). Pipe entrances did not directly affect the amount of sealed brood in a colony nor the temperature inside colonies. However, brood significantly affected temperature inside colonies and there was a tendency for reduced brood in colonies with pipes; temperature increased as the amount of brood in a colony increased. Brood did not affect the number of adult beetles present in colonies. 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.

 

 

 

19. A scientific note on small hive beetle (Aethina tumida Murray) weight, gross biometry, and sex proportion at three locations in the southeastern United States. Ellis, J.D., K.S. Delaplane, W.M. Hood. 2002. American Bee Journal 142(7): 520-522



 

TABLE 1. Gross biometry by sex (m, f) and sex proportion of A. tumida from three populations in the southeastern United States. Values are mean ±-standard error. Numbers in parentheses, n. For length, values within location with different letters are significantly different at the a < 0.05 level. For width and weight, overall means with different letters are significantly different. Analyses were not run for sex proportion because of unequal sample size between locations.
 
length (mm)
width (mm)
weight (mg)
% of popn
Clemson, SC
m
5.6±0.04 (101)b
3.2±0.03 (101)
11.7±0.3 (113)
49.6±4.4 (3)
f
5.8±0.04 (104)a
3.2±0.02 (104)
13.2±0.3 (125)
50.4±4.4 (3)
Wadmalon Island, SC
m
5.6±0.02 (330)b
3.3±0.01 (330)
13.1±0.3 (76)
46.6±2.3 (20)
f
5.8±0.03 (170)a
3.3±0.02 (170)
15.0±0.3 (146)
53.4±2.3 (20)
Richmond Hill, GA
m
5.5±0.02 (250)b
3.1±0.02 (250)
12.4±0.3 (75)
47.4±0.8 (2)
f
5.6±0.02 (248)a
3.2±0.02 (248)
14.1±0.3 (86)
52.6±0.8 (2)
overall means
m
5.5±0.01 (681)
3.2±0.009 (681)a
12.3±0.2 (264)b
47.1±1.9 (25)
f
5.7±0.02 (522)
3.2±0.01 (522)a
14.2±0.2 (357)a
52.9±1.9 (25)




 

20. Honey bee (Hymenoptera : Apidae) pollination of rabbiteye blueberry Vaccinium ashei var. 'Climax' is pollinator density-dependent. Dedej, S. & K.S. Delaplane. 2003. Journal of Economic Entomology 96(4): 1215-1220
PDF file

ABSTRACT To investigate the influence of different population densities of honey bees (Apis mellifera L.) on pollination of rabbiteye blueberry (Vaccinium ashei Reade var. ‘Climax’), a 2-year (2000, 2002) study was conducted at the University of Georgia Horticulture Farm in Oconee County, Georgia. Mature orchard plants plus potted pollenizers (‘Premier’) were caged with varying densities of honey bees (0, 400, 800, 1600, 3200, 6400 or 12800 bees plus open plot) during the bloom interval. The number of legitimate honey bee flower visits / 2 min was repeatedly measured, then at harvest each cage was analyzed for percentage fruit set, berry weight (g), seeds / berry, percentage soluble solids (sucrose content), and speed of ripening (% fruit ripe at an arbitrarily chosen date).

The percentage of legitimate flower visits tended to increase as bee density increased within a range of 400 – 6400 bees; there were more legitimate visits in cages with 6400 bees than in those with =1600 bees (table). Similarly, within a range of 400 – 6400 bees there was a trend for a corresponding increase in fruit set with means ranging from 25.0 – 79 percent. Fruit set was higher in cages with 6400 or 3200 bees than in those with =800 bees. Regression analyses showed that fruit set increased linearly with the number of legitimate bee visits (y = 34.7 + 1.6 x; r2 = 0.66). Mean weight of berries was unaffected by bee density but varied significantly between years. Within a range of 0 – 3200 bees the average seeds / berry tended to increase with increasing bee density; there were more seeds in open plots than in cages with 12800 honey bees or =1600 bees. Sucrose content ranged from 12.1 – 16.7 percent and fruits tended to be sweeter in cages with lower bee densities; percent sucrose was higher in cages with 400 bees than in those with =1600 bees or in open plots. Speed of ripening tended to be higher in cages with higher bee densities, however this trend was weaker than for the other variables; fruit ripening was faster in cages with 3200 bees than in those with =1600 bees or in open plots.

The effectiveness of A. mellifera as a pollinator of rabbiteye blueberry is partly variety-dependent. Honey bees were demonstrated to be inefficient pollinators of ‘Tifblue’ (Cane & Payne, 1990 Alabama Agric. Exp. Sta. 37: 4) but effective for ‘Climax’ (Sampson & Cane, 2000 J. Econ. Entomol. 93: 1726-1731) based on assays of single-bee flower visits. Our results support those of Sampson & Cane, confirming that A. mellifera is an effective pollinator of V. ashei var. ‘Climax.’ Our data further indicate that the effectiveness of A. mellifera is bee density-dependent. Fruit set, seed number, and speed of ripening increased as bee density and flower visitation rates increased. More broadly, our results underscore the need to consider the pollinator densities achievable with candidate pollinator species. It is possible that a relatively inefficient pollinator, as determined by a lack of specialized behaviors or phenologies, may nevertheless be effective if it can field a forager force large enough to effect multiple flower visits. 

 

21. The effects of adult small hive beetles, Aethina tumida (Coleoptera: Nitidulidae), on nests and foraging activity of Cape and European honey bees (Apis mellifera). Ellis, J.D., Jr., R. Hepburn, K.S. Delaplane, P. Neumann, & P.J. Elzen. 2003. Apidologie, 34: 399-408
PDF file

ABSTRACT This study identifies differences in the effects of small hive beetles on flight activity and nests of European-derived honey bees (Apis mellifera) in the United States and Cape honey bees (Apis mellifera capensis) in South Africa. Treatments consisted of control colonies (<5 beetles/colony) and experimental colonies receiving beetles (treatment). Absconding day did not differ significantly between treatment or bee race but absconding was greater between the two treatments in European colonies than in Cape ones.Cape bees used significantly more propolis than European bees. Honey stores were significantly greater in Cape honey bee colonies than in European ones. Bee weight did not differ significantly between treatments or bee race. Treatment did not significantly affect bee populations, brood area, or average flight activity in Cape colonies but it did significantly lower all of these in European colonies. The effects of treatment in European colonies are symptomatic of absconding preparation. Treatment significantly lowered the amount of pollen stores in Cape colonies, but this effect was not found in European colonies. The number of beetles in control colonies was significantly higher in European colonies than Cape ones while the percentage of beetles remaining in non-absconding treated colonies was higher in Cape colonies than European ones. These data indicate that adult small hive beetles are sufficient to cause significant harmful effects on colonies of European, but not Cape, honey bees.

 


22. A scientific note on small hive beetle (Aethina tumida Murray) oviposition and behavior during honey bee (Apis mellifera) winter clusters and absconding events. Ellis, J. D., Jr., R. Hepburn, K. S. Delaplane, & P. J. Elzen. 2003. Journal of Apicultural Research, 42(1-2): 47-48
PDF file

 

 

 


23. Efficacy of modified hive entrances and a bottom screen device for controlling Aethina tumida (Coleoptera: Nitidulidae) infestations in Apis mellifera (Hymenoptera: Apidae) colonies. Ellis, J. D., Jr., K. S. Delaplane, R. Hepburn, & P. J. Elzen. 2004. Journal of Economic Entomology 96(6): 1647-1652
PDF file

ABSTRACT Our earlier work (abstract #19 above) suggested that reducing colony entrances with PVC pipe may impede entry of adult small hive beetles, Aethina tumida, and thus serve as a cultural aid to beetle control. There was evidence, however, that reduced entrances were harmful to brood production. In the current study we compared the efficacy of open entrances, 3/4-inch PVC pipe entrances, or 1.5-inch pipe, with or without a plastic screen (2-mm wide mesh) hive bottom. We conclude that reduced hive entrances with the 1.5-inch (3.8-cm ID) pipe can play a role in the integrated control of the small hive beetle. The 2-mm mesh plastic screen (the kind typically used as a base for cross-stitch crafts) partially offset the negative effects of reduced entrances on brood and adult bee populations.

 

24. Nectar-robbing carpenter bees reduce seed-setting capability of honey bees (Hymenoptera : Apidae) in rabbiteye blueberry Vaccinium ashei, 'Climax.' Dedej, S. & K. S. Delaplane. 2004. Environmental Entomology 33(1): 100-106   PDF file

ABSTRACT The carpenter bee Xylocopa virginica (L.) acts as a primary nectar thief in southeastern plantations of native rabbiteye blueberry Vaccinium ashei Reade, perforating corollae laterally to imbibe nectar. Honey bees (Apis mellifera L.) learn to collect nectar from these perforations and thus become secondary thieves. We conducted a 2-yr study to assess how nectar robbing in honey bees affects fruit production in rabbiteye blueberry. Various harvest parameters were measured from fruit collected from plants tented with: honey bees and carpenter bees (AX), carpenter bees (X), honey bees (A), no bees (0), or in open plots (open). In open plots, rates of illegitimate honey bee flower visitation increase from initial lows to fixation at $95%. Fruit-set is higher in open, A, and AX plots than in X and 0 plots. Even though fruit-set is similar in A and AX plots, seed numbers are significantly reduced in AX plots in which X. virginica-induced illegitimate honey bee flower visitation approaches 40%. Open-pollinated berries were larger than berries from all other treatments in 2001, while in 2002 berry weight followed the pattern A > open > AX > (X~0). Sucrose content of juice and speed of ripening were unaffected by treatments.




25. Hygienic behavior of Cape and European Apis mellifera (Hymenoptera: Apidae) toward Aethina tumida (Coleoptera: Nitidulidae) eggs oviposited in sealed bee brood. Ellis, J. D., Jr., K.S. Delaplane, C.S. Richards, R. Hepburn, J.A. Berry, & P.J. Elzen. 2004. Annals of the Entomological Society of America 97(4): 860-864  PDF file

ABSTRACT In this study, we tested for the presence and efficacy of hygienic behavior by Cape honey bees in South Africa and European honey bees, Apis mellifera L. (Hymenoptera: Apidae), of mixed origin in the United States toward Aethina tumida Murray (Coleoptera: Nitidulidae) eggs oviposited in sealed bee brood. We looked for colony differences in removal rates of brood in cells with cappings perforated by A. tumida within each subspecies to identify colonies within location that display superior hygienic behavior. Finally, we determined the oviposition rate (number of A. tumida-perforated cells actually oviposited in by A. tumida/total number of A. tumida-perforated cells) in A. tumida-perforated cells and the number of A. tumida eggs oviposited in each cell. There were no colony differences within subspecies for the removal of normal capped brood, artificially perforated brood (capped cells perforated by experimenter with a pin), and A. tumida-perforated brood. For both subspecies, the bees removed significantly more A. tumida-perforated brood than either normal or artificially perforated brood. A. tumida oviposited significantly more eggs per cell in Cape colonies than in European colonies, but the oviposition rate in A. tumida-perforated cells did not differ between Cape and European colonies. Both subspecies removed a proportion of A. tumida-perforated brood statistically indistinguishable from the proportion of A. tumida-perforated brood containing A. tumida eggs. Thus, both Cape and European A. mellifera preferentially remove the contents of A. tumida-perforated cells in which A. tumida have actually oviposited.

 

26. Effectiveness of honey bees in delivering the biocontrol agent Bacillus subtilis to blueberry flowers to suppress mummy berry disease. Dedej, S., K.S. Delaplane, and H. Scherm. 2004. Biological Control 31: 422-427  PDF file

ABSTRACT Honey bees are important pollinators of commercial blueberries in the southeastern United States, and blueberry producers often use supplemental bees to achieve adequate fruit set. However, honey bees also vector the plant pathogenic fungus Monilinia vaccinii-corymbosi which infects open blueberry flowers through the gynoecial pathway causing mummy berry disease. Here, we report the results of a 3-year field study to test the hypothesis that using bee hives equipped with dispensers containing the biocontrol product Serenade, a commercial formulation of the bacterium Bacillus subtilis which has shown activity against flower infection by M. vaccinii-corymbosi in laboratory experiments, can reduce mummy berry disease incidence when honey bees are used as pollinators in blueberries. Individual honey bees carried 5.1-6.4 x 105 colony-forming units (CFU) of B. subtilis when exiting hive-mounted dispensers with Serenade. On caged rabbiteye blueberry bushes in the field, population densities of B. subtilis vectored by honey bees reached a carrying capacity of <103 CFU per flower stigma within 2 days of exposure, and there was a highly significant non-linear relationship between B. subtilis populations per stigma and bee activity, expressed as number of legitimate flower visits per time interval per cage (R = 0.6928, P < 0.0001, n = 32). Honey bee density (1600 or 6400 individuals per 5.8-m3 cage) and Serenade treatment (presence or absence of the product in hive-mounted dispensers) significantly (P < 0.05) affected the incidence of fruit mummification on caged bushes, whereby increasing bee density increased disease incidence and application of Serenade reduced disease levels. Taken together, results of this study suggest that use of a hive-dispersed biocontrol product such as Serenade as a supplement during pollination can reduce the risk of mummy berry disease. This may be a prudent practice that optimizes the benefits to pollination of high bee densities while reducing the associated disease-vectoring risk.

 

27. Net energetic advantage drives honey bees (Apis mellifera L) to nectar larceny in Vaccinium ashei Reade. Dedej, S. and K. S. Delaplane. 2005. Behavioral Ecology and Sociobiology 57: 398-403 PDF file

ABSTRACT  Carpenter bees (Xylocopa spp.) act as primary nectar thieves in rabbiteye blueberry (Vaccinium ashei Reade), piercing corollas laterally to imbibe nectar at basal nectaries. Honey bees (Apis mellifera L) learn to visit these perforations and thus become secondary nectar thieves. We tested the hypothesis that honey bees make this behavioral switch in response to an energetic advantage realized by nectar-robbing flower visits. Nectar volume and sugar quantity were higher in intact than perforated flowers, but bees (robbers) visiting perforated flowers were able to extract a higher percentage of available nectar and sugar so that absolute amount of sugar (mg) removed by one bee visit is the same for each flower type. However, because perforated flowers facilitate higher rates of bee flower visitation and the same or higher rates of nectar ingestion, they are rendered more profitable than intact flowers in temporal terms. Accordingly, net energy (J) gain per second flower handling time was higher for robbers on most days sampled. We conclude that the majority evidence indicates an energetic advantage for honey bees that engage in secondary nectar thievery in V. ashei.


 

28. Effect of flower-applied Serenade biofungicide (Bacillus subtilis) on pollination-related variables in rabbiteye blueberry. Ngugi, H.K., S. Dedej, K.S. Delaplane, A.T. Savelle, and H. Scherm. 2005. Biological Control 32: 33-38  PDF file

ABSTRACT Application of Serenade, a commercial biofungicide formulation containing the bacterium Bacillus subtilis, to the stigmatic surface of open blueberry flowers suppresses floral infection by the mummy berry fungus Monilinia vaccinii-corymbosi. The deliberate targeting of the stigma with the biocontrol agent in this pathosystem prompted us to evaluate potential negative impacts on pollination and pollination-related fruit characteristics. Application of Serenade to the stigmatic surface of detached blueberry flowers in the laboratory had no effect (P > 0.05) on the number of pollen tubes entering the style or their growth rates within the stylar canal. There also was no reciprocal effect, i.e., population dynamics of B. subtilis were unaltered by the presence of pollen. In the greenhouse, application of the biocontrol product to open flowers, regardless of whether it was done 1 day before or at the same time as pollination, did not impact fruit set or the number of seeds per berry, but marginally (P = 0.048) affected fruit weight in one of two experimental runs, whereby fruit weights in the two Serenade timing treatments were significantly different from each other but neither was different from that of the control that received pollen only. In an experiment in which honey bees were utilized to vector the biocontrol product to open flowers in the field, application of Serenade did not affect fruit weight but significantly reduced fruit set from 49.1 to 38.1% (P = 0.0382) and seed number to about half of that of the untreated control (P = 0.0109). However, fruit weights and especially seed numbers in this experiment were low even in treatments receiving no Serenade, indicative of poor pollination overall. Taken together, these results indicate that application of Serenade has no adverse effects on pollination and associated fruit characteristics except in conditions marginal for pollination, e.g., when pollen availability is limited.

 

29. Integrated pest management against Varroa destructor reduces colony mite levels and delays economic threshold. Delaplane, K.S., J.A. Berry, J.A. Skinner, J.P. Parkman, & W.M. Hood. 2005. Journal of Apicultural Research 44(4): 117-122  PDF file

ABSTRACT Two independent, long-term (17 months and 87 weeks) studies were done to appraise the effects of published integrated pest management practices on colony varroa mite levels, length of time before onset of treatment threshold, and other measures of colony productivity. Screen hive floors tended to reduce colony mite levels (24-hr sticky sheet counts), sometimes significantly. Likewise, mite-resistant queens tended to cause a numeric and sometimes significant reduction in mite levels; number of mites on sticky sheets decreased as the percentage expression of hygienic behavior in a colony increased, and on the majority of sampling episodes the number of mites retrieved on sticky sheets was numerically lower in colonies with queens expressing suppressed mite reproduction (SMR). In six of eight cases when IPM components were found to interact they did so in a manner favorable to mite control. Time until achieving treatment threshold was significantly delayed in colonies with SMR queens (ca. 72 weeks) compared to non-selected queens (59). In one experiment, stored honey was significantly reduced in colonies with screens (3.8 frames) compared to solid floors (5.1); likewise, stored pollen was lower in screen colonies (0.9 frames) than on solid floors (1.3). SMR queens tended to have reduced brood production.

 

 

30. An evaluation of Fruit-Boost™ in enhancing honey bee pollination of seedless watermelons. Ellis, A. M. & K. S. Delaplane. 2005. Final Report to Zeraim Gedera Seed Company and Phero Tech, Inc.

ABSTRACT Six 20 18 m experimental plots were each interplanted with triploid 'Sugar Heart' (main variety) and diploid 'Crimson Sweet' (pollenizer) watermelons. The study was conducted under conditions of pollinator (honey bee) competition with nearby sunflower. Each plot received one of two experimental treatments, application of Fruit Boost™ honey bee attractant or application of water control. There was a significant decrease in the proportion of true bugs (Hemiptera) in Fruit Boost plots compared to controls. There was a numeric increase in total number of honey bee flower visitors in plots treated with Fruit Boost compared to controls; however, the effect was not significant. There was a significant and stepwise decrease in number of honey bee visitors from week 1 to week 3; it is noteworthy that sunflower began blooming in week 2. Fruit Boost did not significantly increase the proportion of honey bee visits that occurred on female flowers. There was a numeric increase in percent fruit-set in Fruit Boost plots compared to controls; however, this effect was not significant. Average weight per triploid melon was unaffected by treatment and ranged from 0.2-11.6 kg.

 

 

31. The effects of habitat type, ApilifeVAR™, and screened bottom boards on small hive beetle (Aethina tumida) entry into honey bee (Apis mellifera) colonies. Ellis, J.D. and K.S. Delaplane. 2006. American Bee Journal 146(6): 537-539  PDF file

ABSTRACT In this study we investigated how habitat type (open field vs. shaded area), Apilife VAR™, and screened bottom boards affect small hive beetle (Aethina tumida) entry into honey bee (Apis mellifera) colonies in late summer and fall. Data on ending number of beetles and number of deep frames of bees, pollen, honey and total brood were collected on day 27 for both of two trials. Bottom screens failed to repel beetles, although their use did not lead to greater beetle populations in test colonies. Bottom board type did not affect any of the colony strength parameters except honey in trial 2 (more honey in colonies with conventional wooden bottom boards than screened ones). The use of Apilife VAR did not affect beetle entry or any of the colony strength parameters. Habitat type did not affect any of the measured parameters except honey (more honey in colonies in the open than shaded area). The data suggest that small hive beetles disperse within an apiary, at least initially, without regard to habitat, presence of Apilife VAR, or screened bottom boards.


32. The effects of three acaricides on the developmental biology of small hive beetles (Aethina tumida). Ellis, J. D. & K. S. Delaplane. 2007. Journal of Apicultural Research and Bee World 46(4): 256-259 
PDF file

ABSTRACT Small hive beetles (Aethina tumida, SHB) are an emerging problem for beekeepers internationally. Here we report how SHB development is affected by three acaricides, representing three chemical classes, that are used to control varroa mites (Varroa destructor): pyrethroids (fluvalinate - Apistan®), botanical extracts (thymol, camphor, menthol, eucalyptol - Apilife VAR®), and organophosphates (coumaphos - Checkmite+®). Our data indicate that the three acaricides vary in toxicity to SHB developmental stages. Apistan was toxic to feeding and wandering larvae but innocuous to adults while Apilife VAR only exhibited toxicity to perpetually-wandering larvae. Checkmite+ had the broadest toxicity, killing both larvae and adults. The three acaricides only affected pupal development with regard to d spent pupating. There was no increased mortality in pupae that were exposed to the acaricides as feeding or wandering larvae. Our data are useful for developing chemical controls for various developmental stages of SHB by demonstrating which developmental stages are most vulnerable to three chemical treatments.