Final Report for OS04-022
Project Information
The small hive beetle has become a significant pest of beehives in the United States over the past 10 years. Although the beetle is distributed broadly, little information is available on spread, host habitat outside of beehives, or population densities. The best way to gain insight into these factors is through the use of effective monitoring traps. Scientists at the Center for Medical Agricultural and Veterinary Entomology, USDA, ARS Gainesville Florida, the University of Florida and the Pennsylvania State University have developed a new highly effective attractant and trap combination that allows for effective population monitoring of this invasive pest. Using the trap-lure combination at sites in Florida and Pennsylvania the team has discovered that most beetles were captured at the bottom of the hive and that infestation was heavily distributed in only about 25% of the colonies. During the period of the study, project participants attended 11 beekeeper meetings and held 3 short courses and 1 field day demonstration on the small hive beetle trapping system. Furthermore, one piece of educational material on the beetle was prepared for beekeepers and one scientific manuscript was submitted for publication. The development of the trap and lure combination will greatly aid research on the population dynamics of the small hive beetle.
Introduction
The apiculture industry is a vital component of modern agriculture in the US. Sales of honey, beeswax, and other bee products represent a significant part of this contribution. However, the most significant economic impact of the apiculture industry to US agriculture is from pollination services provided by managed honey bee colonies. An estimated 250,000 hives are managed in Florida, producing about $11 million worth of honey, and providing pollination services to the 35,000 acres of fruit and vegetable crops at an estimated value of about $30 million. In Pennsylvania, an estimated 30,000 honey bee colonies produce about $1.3 million worth of honey, with pollination services valued at about $53 million. Surveys also show that about 27% of beekeepers in Florida manage migratory beekeeping operations for 6 months outside the state, involving 62% of honeybee colonies, to pollinate melon, pumpkin, cucumber and blueberries.
Surveys of beekeepers by various universities and state agencies identify exotic pests as major constraints to the beekeeping industry. At various meetings of the Florida State Beekeepers Association and the Mid-Atlantic Bee Research and Extension Consortium (MARREC), beekeepers and industry leaders identified the exotic parasitic pests Varroa destructor (Anderson), and the small hive beetle (SHB) Aethina tumida Murray as the leading threats to the beekeeping industry. The migratory nature of the apiculture industry and the increasing demands for pollination services by honeybees are largely responsible for the quick spread of exotic parasitic honey bee pests in the US. In the past 5 years, Florida suffered a loss of about 30 % of managed honey bee colonies due to exotic parasitic pests, with Pennsylvania recording a loss of about 68% in the last 20 years. This suggests that there is a clear need to safeguard the remaining honeybee colonies in the industry by developing cheap and effective control measures for these pests.
The small hive beetle, a nitidulid beetle, was first discovered destroying honey bee colonies in Florida in 1998. In South Africa, native land of the small hive beetle, it is not considered a significant pest. In the US, it attacks both weak and strong honeybee colonies. Statistical data is not available on the impact of the beetle on the beekeeping industry in the 16 states in the US it has spread to since its discovery in Florida. However, the Apiary Division of the Florida Department of Plant Industry and the Florida Farm Bureau estimate that since its introduction into the US, the beetle has contributed to the collapse of thousands of hives, damaged countless stored combs, and destroyed several pounds of unprocessed honey. Basic biology of this pest is rather scanty, but adult beetles have been found to live up to 12 months, with each female laying about 3000 eggs in the host colony. Emerged larvae are most damaging to the honey bee colony, feeding on honey, pollen and brood. They defecate in the honey causing it to ferment and rendering it unfit for human consumption. Badly infested hives with frothy, fermented honey are eventually abandoned by the bees. In the final instar stage, larvae leave the hive to pupate in the soil, preferably in sandy soil, although the beetle can complete its life cycle in clay soil. Emerging adults can infest colonies nearby or fly several miles to infest other colonies. Beetles are also known to overwinter in the cluster of wintering hives in northern states. In Florida and elsewhere in the south, the worse infestation periods are between May and October when the climatic conditions favor the small hive beetle’s rapid reproduction and dispersal. To date, there are no effective control measures for the beetle.
At the USDA, ARS-CMAVE in Gainesville, we have developed a cheap, environmentally-friendly and an effective trapping system for the small hive beetle. This trapping system consists of an in-hive trap baited with a highly attractive lure that can be used to monitor and mass trap adult beetles (Torto et al. unpublished results). Estimated to cost about $20, the baited trap can be fitted and removed from the hive without disturbing bees. The trap also has the potential of reducing the level of infestation by wax moth larvae, not counted in this study, but which were also found in some of the baited traps.
The purpose of this study is to evaluate on a large scale in Florida, Pennsylvania and Delaware the effectiveness of the baited trap in mass trapping beetles from honeybee colonies. It is anticipated that a few commercial, hobbyist beekeepers and bee inspectors will be involved in the evaluation.
To monitor beetle populations from honeybee colonies at sites in Florida, Delaware and Pennsylvania.
To to test the potential of the trapping system in monitoring wax moth larval populations in honeybee colonies.
To monitor the number of larvae leaving host colony to pupate.
To test the potential of the trapping system in monitoring Varroa mite populations in honeybee colonies.
To monitor the number of queen replacements
To quantify bee hygienic behavior with respect to removal of small hive beetle larvae
To quantify brood area in colonies
Cooperators
Research
Field sites. Experiments were carried in Florida, Delaware and Pennsylvania, all in apiaries with a previous history of SHB outbreaks. There were four sites in north-central Florida, one near High Springs in Alachua County (29.8 ºN, 82.6 ºW) and three at various locations in Columbia County (Sites A and B at 30.2 ºN, 82.4 ºW and Site C at 30.1 ºN, 82.4 ºW). There were three sites in Suffix County, Delaware located within 6.4 km of one another: (Site 1 at 38.7 ºN, 75.6 ºW; Site 2 at 38.7 ºN, 75.5 ºW, and Site 3 at 38.6 ºN, 75.6 º). One site (Site 4) was located in Montgomery County, Pennsylvania (40.1 ºN, 75.2 ºW). All the experiments were conducted between June and October of 2003, 2004 and/or 2005.
(Any Tables, figures or graphs mentioned in this report are on file in the Southern SARE office.
Contact Sue Blum at 770-229-3350 or
sueblum@southernsare.org for a hard copy.)
Trap. The trap consists of three parts (Fig. 1). The upper part is a typical Langstroth hive bottom board that was modified by cutting a rectangular opening (18 x 14 cm) in its center. This opening was covered with a piece of 4-mesh aluminum screen, which allowed beetles to pass through but excluded bees. The modified bottom board was attached to a three-sided frame of two-by-fours, whose missing side was either toward the back or side of the hive. This opening permitted a plywood panel to slide beneath the bottom board on wooden runners that were attached to the two-by-four frame. This panel, like the bottom board, had an 18 x 14-cm rectangular opening in its center, and when in place, this hole aligned with that in the modified bottom board. The lid of a Rubbermaid® egg container (Rubbermaid, Huntersville, North Carolina, USA) was attached to the underside of the sliding panel. Two openings cut in the middle of the lid were fitted with PCR 96 well plates that had their conical tips cut off and were positioned with the tips extended downward. The egg tray, which contained the bait and held trapped beetles, snapped into this lid. Because SHBs are attracted to dark shaded areas (Torto et al., 2006), the Rubbermaid® egg containers were sprayed with black paint (Rust-Oleum Corporation, Vernon Hills, Illinois, USA) before use, to enhance the efficacy of the trap. Three pin holes drilled into each corner cell of the egg container allowed for drainage of water that entered the trap.
Bait. The bait was prepared by feeding adult beetles on pollen dough as previously described (Torto et al., 2006). Briefly, adult male beetles (300, 4-8 weeks old) were allowed to feed on moistened dough prepared in the laboratory from commercially packaged bee pollen (Y.S. Organic Bee Farms, Sheridan, Illinois, USA), commercial pollen substitute (Bee Pro, Mann Lake Ltd., Hackensack, MN, USA) and warm honey (1: 12:18) After 3 weeks of feeding in a room maintained at 26 ºC, the fermenting pollen dough was thoroughly mixed and 100 g was scooped with an ice cream scoop into a cotton stockinette (Florida Orthopedics, Inc, Miramar, Florida, USA). The ends of the stockinette were then tied off with rubber bands. The bagged beetle-fed upon pollen dough was transferred into Ziploc bags and stored in the refrigerator at 4 ºC until used.
Baited traps were prepared by placing a bag of pollen dough fed upon by adult males of the beetle and a piece of cotton stockinette (10 cm x 10 cm) moistened with water (~ 20 ml) into the egg container, while unbaited traps had only a piece of moistened stockinette.
Experiment I. The purpose of this experiment, which was done in both Florida and Pennsylvania at commercial beekeeper sites during the period 2004-2005, was to compare the effectiveness of baited and unbaited in-hive traps installed in standard Langstroth hives. In 2004, the test was run for 12 weeks (July 19 to October 13) at an apiary in Lake City (site A) on colonies in double deep brood chambers positioned on 8 palettes, with four colonies per palette. On each palette, baited and unbaited traps were installed in hives that were side by side. There were two baited and two unbaited traps per palette. We observed in our 2004 tests that the bait and moistened cotton stockinette had dried out in some of the traps by the next count. Thus, in the third test, run in 2005, 5% glycerol was added to the bait, and 20% glycerol in water was used as the moisture source to increase water absorption. This test was run for 18 weeks (June 2 to October 12) at another apiary located near Lake City (site B) on 12 colonies. Eleven of these colonies were one and a half deep brood chambers, while the twelfth was a single brood chamber. A similar test was run in 2005 in Pennsylvania for 7 weeks with the modified bait containing glycerol. In the 2004 and 2005 tests, traps were emptied every week between 10.00 am and noon, the lure was replaced and the trapped beetles were counted. In all of the 2003, 2004 and 2005 tests, except for the test run in Pennsylvania, the distribution of baited and unbaited traps among hives was reversed half way through the experimental period. Results from these studies were compared with a test carried out in 2003 for 24 days (September 18 to October 12) at an apiary in High Springs, Florida on 10 colonies contained in single deep brood chambers. Five colonies had baited traps, and five had unbaited traps. Traps were emptied every 2 days between noon and 2.00 pm and the captured beetles removed and counted. The lures were replaced every 6 days.
Experiment II. This study was conducted at commercial beekeeper sites in Delaware and Pennsylvania in 2004 to compare the effectiveness of the in-hive baited trap as a bottom or top board trap. A total of four apiaries, with a minimum of 12 hives were used. Three of these apiaries were located in Delaware (Sites 1-3) and they all had over-wintered colonies maintained in one and a half brood chambers. These colonies had been moved from Virginia to Delaware to pollinate water melons. The fourth site was located in Montgomery Co, Pennsylvania and it had colonies in double story deep brood chambers established from bee packages earlier in the year. All the colonies at the Delaware apiaries were managed on palettes, with 4 colonies/palette. Treatments were randomly assigned to 2 groups of 4 colonies in each apiary. In the Delaware apiaries, each group of 4 colonies was on the same palette. One treatment group had baited bottom board traps and the second group had a similar baited trap placed in an empty super over the colony inner cover. Traps were emptied weekly until August 2 in the Pennsylvania apiary and until August 25, 2004 in the three Delaware apiaries. SHB captures were pooled in each apiary for each treatment group and counted.
Statistical Analysis. Weekly counts in Experiment I were summed for each treatment (baited and unbaited) over the entire trapping period for each year and location, and the trap totals were analyzed. The transformation log (x + 1) was applied to the totals before analysis to meet assumptions of normality and equal variance. Analysis of variance (PROC GLM, SAS Institute Version 8) was performed to compare mean numbers captured by baited and unbaited traps each year at each location. In Experiment II, the effects of trap position in the hive (top or bottom), geographical location of the apiary, and interaction between these two factors on the number of SHBs captured were examined by analysis of variance (Proc GLM, SAS Institute Version 8). As in Experiment I, the numbers of SHBs captured were transformed (log x + 1) to meet assumptions of normality and equal variance. Multiple comparisons were made with Dunnett’s test.
Small Hive beetle adult captures
In Experiment I, baited traps captured significantly more SHBs than unbaited traps at all sites (Fig. 2). Total captures were as follows: High Springs (2003), 720 SHBs (baited, 625; unbaited, 95) captured during the 24 day trapping period; Lake City, site A (2004), 796 SHBs (baited, 714; unbaited, 82) captured in 12 weeks; Lake City, site B (2005), 1372 SHBs (baited, 1017; unbaited, 355) captured in 18 weeks; Morris Arboretum, Pennsylvania (2005), 671 SHBs (baited, 458; unbaited, 213) captured in 7 weeks.
Trap captures at the Lake City site used in 2005 was further analyzed to determine the distribution of SHBs in honeybee colonies with the goal to identify a simple and a cheap mass trapping strategy for the beetle for use by the commercial beekeeper. In Fig. 3, each bubble on a honeybee colony represents a proportion of the total of SHB captured from 12 colonies. Of 12 honeybee colonies monitored, three (25%) showed high SHB infestation suggesting that SHBs use a mass attack strategy to infest honeybee colonies in order to gain access to the hive resources for their survival. The implication of these results is that colonies that are heavily infested with SHBs when fitted with in-hive baited traps can potentially be used as a sponge to mass trap the beetle at a commercial beekeeper's apiary.
In Experiment II, trap captures indicated that there was no interaction between apiary and trap position (F (3, 29) = 1.93, P = 0.15) (Table 1). The number of adult beetles trapped differed between apiaries (F (1, 32) = 23.01, P < 0.02) and between trap positions (F(1, 32) = 9.98, P < 0.01) (Table 2). Of a total of 1321 SHBs caught at the four sites, 1213 (~92%) were captured from one site, with ~94% of these beetles caught in the baited bottom board trap.
In 2004, at a hobbyist site in Florida, SHB levels were monitored with baited in-hive traps in two honeybee colonies separated by approx. 30 meters. One colony was located in deep shade, with the other colony placed in direct sunlight. The pattern of trap capture (Fig. 4) indicated a higher SHB infestation of the colony located in the deep shade than that located in direct sunlight. Based on these results and previous trapping studies with flight traps in Florida and Pennsylvania (Torto et al., 2006), a fact sheet on how to minimize exposure of honeybee colonies to small hive beetles was prepared for use by beekeepers (see Publications/Outreach).
Small Hive Beetle (SHB) Larval Captures
In Experiment I, baited traps captured significantly large numbers of SHB larvae at different stages of development at all the sites in Florida, Pennsylvania and Delaware during the trapping periods in 2004 and 2005. This was unexpected. A representative graph comparing the number of adult with larvae of the beetle captured from one honeybee hive at Lake City, Florida in October 2004 is shown in Fig. 4. A total of 614 adults and 2308 larvae of the SHB were captured in one baited trap during a 4 week trapping period. However, inspection of this colony, like the other experimental colonies, revealed no larvae inside the hives. Thus the presence of larvae in the traps suggested that the trap environment was conducive to mating and oviposition. These results clearly demonstrated the importance of trapping beetles from colonies because given the opportunity, such as in a weak colony, adult females of the SHB could lay large numbers of eggs which would emerge into destructive larvae within a short time.
At the time of writing this report, a new, less expensive trap and lure which works with an environmentally-friendly killing agent for both adults and larvae of the SHB, but not harmful to honeybees had been developed by the USDA/ARS-CMAVE for use by beekeepers.
A demonstration of the use of the trapping system with living SHBs in a hive was carried out by Drs. Peter Teal and Baldwyn Torto recently at the First Annual Florida State Beekeepers Association (FSBA ) Spring Meeting in Seffner, Florida (May 27, 2006). (See story at link < http://floridabeekeepers.org>)
Wax moth
In Experiment I carried out in 2004, baited and unbaited traps captured no wax moth larvae at all the sites in Delaware and Pennsylvania during the 14 and 8 weeks trapping periods, respectively. Generally, weekly trap captures of wax moth larvae and adults at the sites in Florida were low, 0-5 larvae/baited trap, suggesting that wax moth was not a serious pest at these sites. However, at one hobbyist site, trap capture indicated that the wax moth was the key pest in one of two hives used in the trial. Total trap captures were as follows: Hive 1 (wax moth, 2; SHB, 77) and Hive 2 (wax moth, 417; SHB, 33) captured during the 6 weeks trapping period.
Varroa mite
In all the experiments, Varroa mites were captured in both baited and unbaited traps. Preliminary counts indicated no significant difference in the numbers of the mites captured in baited and unbaited traps suggesting that the baited traps were not attractive to the mites. No further counts on Varroa mites were made in subsequent experiments.
The following three objectives: To monitor the number of queen replacements; to quantify bee hygienic behavior with respect to removal of small hive beetle larvae; and to quantify brood area in colonies, were not investigated during the study because of the pest and disease complex in the experimental colonies.
Educational & Outreach Activities
Participation Summary:
Educational Material.
One eductaional material was prepared for beekeepers and bee inspectors in Florida and bee inspectors in Penn. State entitiled
"Minimization of Exposure of Honeybee Colonies to Small Hive Beetle Attack"
This information is available to all the memebers of the Florida Beekeepers Association and is available on their website.
During the period of the study, presentations, short courses and demonstrations on the small hive beetle and the use of the in-hive trapping system were given by various participants on the project at the following:
Presentations
2004
The Florida State Beekeepers Association 84th Annual Convention, Chipley, November 11-13.
The 100th Anniversary of the Pennsylvania Beekeepers Association, November 10.
Tennessee State Beekeepers Association, Oct 10
2005
Penn. State Beekeepers Association. November 11.
85th annual convention of the Florida State Bekeepers Association, St Augustine, November 10-12
62nd Annual American Beekeeping Federation Convention, Reno, January 12-15.
North Carolina State Beekeepers Association meeting.
21st Annual meeting of the International Society of Chemical Ecology, Washington Dc., July 23-27.
2006.
63rd Annual American Beekeeping Convention, Louisville, Kentucky, January 11-14.
Florida State Beekeepers Association Technical Committee, Tallahassee, April 21
Western State Beekeepers Association in Penn. State, February 18.
Short courses in 2006
Delaware State Beekeepers Association, April 22.
Rhode Island Beekeepers Association, April 23
Capital Area Beekeepers Association in Penn. State, April 29.
Demonstration
First Annual Florida State Beekeepers Association Spring Meeting, Seffner, May 27.
One scientific publication has been submitted to the Journal Envrionmental Entomology for consideration for publication.
Project Outcomes
Demonstrable impacts to date.
Developed the first effective method to monitor populations of the SHB in beeyards. Unitl this discovery, apiculturists had no scientific way to determine where hive beetles were in honeybee colonies.
Developed a process for producing the lure for SHBs which is effective, inexpensive and readily available to beekeepers.
Developed a modified in-hive trap for SHBs that is inexpensive, effective and can be easily built by beekeepers and where to place it.
Beekeepers are satisfied that they now have an effective way to trap the SHB that does not require chemical pesticide treatment.
Future Impact
Small scale beekepeers and sideliners will be able to control SHB populations effectively.
Farmer Adoption
A field day was held at the First Annual Florida State Beekeepers Association Spring meeting on May 27, 2006 at the Hillsborough County Agricultural Extension Office in Seffner, Florida for 30 beekeepers, extensionists and bee inspectors. The demonstration was on the new trapping system for the small hive beetle. Live beetles were used. After the demonstration a Material Transfer Agreement on the trapping system was distributed to all the participants as part of our beekeeper adoption process.
Areas needing additional study
Expand outreach program to other states with SHB problem- we have intiated this process by involving the bee inspector in Arkansas and the Bee extensionist at Clemson University to test our new traps and/or lure in monitoring SHBs.
Need to organize a workshop to provide bee inspectors from SHB problem States with the knowledge of SHB monitoring and mass trapping.
Expand the trapping system to allow for control of other bee pests.