The fight against Aethina tumida.

Inhaltsverzeichnis[Verbergen]

The Congress sessions on the small hive beetle occurred over two intense days full of contributions and positive dialogue between stakeholders with very diverse approaches and roles.
In this work, participants examined reports from entomologists, veterinarians, researchers, managers and beekeeping associations representatives: Walter Haefeker, Pietro Massimiliano Bianco, Valter Bellucci, Pio Roversi, Stefano Maini, Michele Dottori, Orlando Campolo, Jeff Pettis, Peter Neumann, Franck Ouessou, Sebastian Spiewok, Nicholas Annand, Michele Mortarino, Andrea Maroni Ponti, Antonio Nanetti, Giovanni Formato, Raffaele Denami, Diego Pagani, Vanni Floris, Giorgio Baracani, Riccardo Cabbri, Claudio Porrini, Giovanni Guido, Umberto Vesco, Marc Oliver Schäfer, Noa Simon Delso.
There were several contributions and questions by the audience, which was following with undivided attention the challenging work of the Congress.
We thank everyone who accepted the invitation to participate in Beecome 2017, and in particular the leaders of the EU Commission (DG SANTE Animal Health), EU Agency EFSA, the FVE (Vétérinaires Association Européen), of EURLab.
On the third day, during the Beecome 2017 session on varroa mite disease and contamination, a qualified board of researchers, veterinarians, and beekeepers led by Etienne Bruneau, the Miele Group chairman of Copa-Cogeca, drafted the document synthesis and proposals on combating the small hive beetle, recording the important and significant consensus of the participants.
On behalf of the European and Italian beekeeping associations that promoted Beecome 2017, we express:

  • The sincerest thanks to all those who have labored in various ways and committed to the full success of this important and unusual initiative.
  • Appreciation for the exceptional and positive effort made in comparing and combining different approaches, sometimes coming from very divergent viewpoints.
  • And thus, full satisfaction in the production of a document that contains essential guidelines and proposals for how to constructively deal with the emergence of this new beekeeping pest in Italy and Europe.

    Francesco Panella
    Novi Ligure March 30, 2017

Introduction

 Aethina tumida, also known as small hive beetle (SHB), is a pest native to sub-Saharan Africa that infests honeybee nests. Recently introduced into different parts of the world it can cause sometimes severe damage to hives of the European honeybee subspecies. Aethina tumida has proven to be a highly invasive species. It has spread and is permanently established now in large areas in Northern America and Australia (Neumann et al. 2016).
To preserve apiculture, the species has been added to the lists of notifiable diseases of OIE (Terrestrial Animal Code), EU (Dir. 92/65/CEE) and Italy (DPR 320/54). Aethina tumida is not a zoonotic agent and no further impact on the environment apart from infesting bee colonies and thereby influencing the pollination activity has been observed. For this reason, the aim of all initiatives from public services and other involved subjects should be to preserve the beekeeping sector, following appropriate analysis of costs and benefits of adopted measures.


Beecome2017

It is not up to the participants of this congress to make decisions about specific procedures and measures of the veterinary authorities. However, the technical/scientific dialogue among veterinarians, entomologists, researchers, beekeepers and their associations during this congress provides the basis for a new direction about the control of Aethina tumida in Europe and the priorities to face this emergency.

 

About Aethina tumida

  1. SHB is free-flying in contrast to other bee pests, e.g. varroa.
  2. SHB life cycle is normally only completed when SHB pupate in the soil (Lundie 1940). That’s why environmental conditions, in particular temperature and humidity, are critical (Ellis et al. 2004).
  3. The life cycle of Aethina tumida is usually connected to honeybee nests, but laboratory experiments indicate that it might be a facultative parasite. The reproduction of SHB in bumblebee nests and on fruit has been demonstrated (Ambrose et al. 2000; Ellis et al. 2002; Spiewok & Neumann 2006; Buchholz et al. 2008; Hoffmann et al. 2008).
  4. The length of the life cycle depends on temperature: adult beetles do not lay eggs at temperatures below 15 °C and larvae also do not hatch from eggs below 15 °C. At 21 °C larvae hatch after 62 hours, at 35 °C after 22 hours. The pupal phase lasts two to six weeks. Pupae do not develop at soil temperatures below 13 °C. Adult beetles succumb to temperatures below 0 °C (Lundie 1940; de Guzman & Frake 2007; Meikle & Patt 2011; Bernier et al. 2014).
  5. Hot and humid conditions are optimal for the reproduction of Aethina tumida. The possible number of reproductive cycles during the season is lower in temperate climate compared to subtropical and tropical regions (Lundie 1940; Bernier et al. 2014).
  6. In regions with temperate climate populations of Aethina tumida build up during summer time showing a peak at the end of summer and autumn. Afterwards beetle numbers decline during winter and spring (de Guzman et al. 2010; Annand 2011).
  7. Generally, a healthy honeybee colony can coexist with Aethina tumida (Spiewok et al. 2007; Neumann et al. 2016).
  8. No fixed threshold exists when small hive beetles become a problem for honey bee colonies. Colonies of the European honey bee with more than a thousand beetles have been observed showing no signs of damage while colonies with only a few dozens of beetles succumbed to Aethina tumida. The most important factor seems to be that the colony is strong enough to defend all combs (Lundie 1940; Spiewok et al. 2007).
  9. Aethina tumida can be attracted to both strong and to weak colonies (Spiewok et al. 2007; Annand 2011; Mustafa et al. 2014). The beetles are attracted by volatiles released by honeybees and honeybee products but also by yeasts – in particular Kodamea ohmeri which is linked to the beetle (Benda et al. 2008) – that naturally occur within the colonies or in beekeeper-added pollen supplements. The presence or absence of honeybee queens does not seem to strongly influence the attractiveness of a colony (Spiewok et al. 2007).
  10. Especially during the warm season a considerable number of beetles can rest outside the colonies hiding under the hive or in the litter (Annand 2011).

 

Sanitary measures in beekeeping

  1. The possibilities to confine an outbreak of certain honeybee diseases are limited due to the free flying nature of individual bees.
  2. Any measures designed to control an outbreak can fail, if the presence of feral colonies as well as other colonies not managed by beekeepers is not taken into account as a potential reservoir.
  3. Compared to other sectors of animal husbandry it is difficult if not impossible to trace the bees of a beekeeper. For example, bees cannot get an earmark. An identifying mark at the hive box does not permit to track the honeybee colony, since hive material gets usually exchanged. Furthermore, uniting and splitting colonies is a necessary part of the common beekeeping practice.
  4. Many beekeeping operations rely on transhumance to be profitable. The movement of apiaries is important for the honey and pollen production and for pollination service. The movement of hives is also necessary due to management needs like the overwintering of colonies or the avoidance of areas with pesticide treatments.
  5. In general, commercial beekeeping operations manage several apiaries. For example, according to the National Beekeeping Register, in Calabria Region there were about 65,000 hives in about 1,700 apiaries, with 88% of hives managed by beekeeping operations which own more than one apiary. In case of an outbreak all apiaries and other facilities of the affected beekeeping operation as well as the movements between those facilities (e.g. from/to the honey house) have to be considered for sanitary measures. This is necessary due to the intensive exchange of bees, combs, unprocessed bee products and hive material within one beekeeping operation. Otherwise adopted sanitary measures are likely to fail. The control of transhumance alone is not enough to confine an outbreak.
  6. According to the last census 2016, there are about 45,500 beekeepers and 72,000 apiaries in Italy, 880,000 hives out of 1,140,000 hives are managed by commercial operations. The different beekeeping methods, applied techniques, management abilities and aims have to be considered, when attempting to set a common goal and to ensure that possible mandatory measures will be implemented.

 

Involving beekeepers in sanitary measures against Aethina tumida

  1. It is fundamental to include all the people that can help to prevent or at least to slow down the spread of Aethina tumida. The beekeepers in the infested areas and in the surveillance zones have to be involved into the measures against Aethina tumida. Without the collaboration of beekeepers, a successful monitoring or control of a pest seems to be unlikely (Thrusfield 1997).
    The perspective of drastic measures, like the burning of hives and apiaries, has affected the collaboration of beekeepers. Authorities cannot expect full cooperation with measures that threaten the very existence of the beekeepers business. If there is strong evidence, that measures are unlikely to work or are even counterproductive, beekeepers are even less likely to cooperate. Confidence in the successful control of Aethina tumida has to be the main incentive for controlling this pest.
  2. It is necessary that the economic damage suffered by beekeepers because of compulsory control measures is quickly and fairly compensated. This is important to maintain the collaboration of the beekeepers.
  3. An intensive information and training campaign concerning the monitoring and control of Aethina tumida should be coordinated by veterinary service and beekeeping associations. The spread of good beekeeping practices including the management of hives, equipment and honey extraction should be supported (Hood 2004).
  4. Beekeepers associations can play a very important role by informing and training the beekeepers and by supporting the sanitary authorities (Gallo & Waitt 2011).

 

Possible factors influencing the spread of Aethina tumida

  1. Due to its flight ability Aethina tumida can actively spread between colonies and apiaries. Its flight activity peak is between two hours before and one hour after sunset (Annand 2011). It is not known how far Aethina tumida can fly but the flight distance of insects can be stronglyincreased by wind (Compton 2002).
  2. The spread of Aethina tumida is facilitated by transhumance and the movement of used beekeeping equipment. This includes for example also the transport of honey supers from and to the honey house. Actually, human mediated spread is the main mode of dispersal over long distances (Hood 2000; Caron et al. 2001; Evans et al. 2003; Annand 2011).
  3. The density of apiaries in a territory and its geographical characteristics are important critical factors influencing the spread of Aethina tumida (Spiewok et al. 2007, 2008).
  4. The routine manipulation of a colony by the beekeeper, the movement of a colony or the inspection by a veterinarian can incite some beetles to leave the hive (Annand 2011).
  5. The movement of hives or the destruction of an apiary can induce the spread of remaining beetles (e.g. in the litter) to neighbouring apiaries if they do not get caught by effective traps or sentinel hives equipped with effective traps.
  6. Aethina tumida can also be found in honeybee swarms and can reproduce in feral colonies providing a reservoir population of SHB that is outside of our current detection methods (Lundie 1940; Ellis et al. 2003; Gillespie et al. 2003; Spiewok & Neumann 2006).

 

Detection/monitoring of Aethina tumida

  1. It can be supposed that during the first phase of an invasion the population size of the pest is still small. The probability to detect it by chance is very low. Therefore, an active and passive surveillance with a strong focus on the use of traps is necessary in areas where Aethina tumida is not present yet (Mehta et al. 2007).
  2. The search for Aethina tumida in the hives needs time and knowledge especially if beetle populations are small.
  3. A skilled operator can check 20-30 hives/day, depending on the strength of the colonies. However, inspections should not rely only on visual controls since beetles can be easily missed when beetle numbers are low (Spiewok et al. 2007). This is especially the case when only “light” screening methods are applied. As a consequence, effective traps that beetles cannot escape should be used to reinforce the monitoring.
  4. The sensitivity of PCR to test hive debris for Aethina tumida (Ward et al. 2007) should be checked and validated.

 

Endemic zones

  1. Despite the burning of infested apiaries during the last three years, the small hive beetle was still reported to be present in many apiaries of the currently infested zone in Calabria in the 3rd year (IZSVE 2016). Therefore Aethina tumida should be declared endemic to this area and appropriate management measures should replace the attempt to eradicate the beetle.
  2. A wide variety of traps are already in use in North America and Australia (Torto et al. 2007; Annand 2008; Nolan 2008; Arbogast et al. 2009; Duehl et al. 2012; Peterson 2012; de Guzman et al. 2013; Levot et al. 2015; Bernier et al. 2015). These traps are available on the world market. Distribute those traps in the infested zones and neighbouring zones to the beekeepers, to reduce the beetle population and to prevent its reproduction. The different traps fit to different beekeeping styles. It is important that the traps retain the beetles and do not release them again. Some of the traps rely on active substances to accomplish this, which may require authorization or the use of the cascade system.
  3. Treatments that involve the direct contact of a medicament with bees and bee products or might contaminate bee products in any other way should not be used (Valdovinos-Flores et al. 2016). Existing traps with a record of effectiveness from other countries should be used. It is not necessary to study the available traps again in detail where data are available. However, an accompanying study in the affected area is recommended. The aim of the applied study should be to detect the possibility for improvements concerning the use of traps and the handling of colonies when SHB are present. Furthermore, it should identify possible remaining problems and find solutions in collaboration with the beekeepers.
  4. It could be useful to identify insecticides that quickly kill Aethina tumida and can be registered for in-hive use (Kanga & Somorin 2012; Pitan et al. 2015). The application method has to exclude a possible contamination of the hive and the environment. Appropriate trap designs were already developed.
  5. In case of SHB mass reproduction, the soil should be treated by synthetic or biological agents around affected hives (Levot & Haque 2006; Muerrle et al. 2006; Buchholz et al. 2009; Ellis et al. 2010; Hill et al. 2016).
  6. Promote the purchase of equipment that allows the optimal management in the honey house of unattended material (e.g. dehumidifiers, refrigerated rooms).
  7. The movement within the endemic zone should be allowed.

 

Protection zones

  1. A protection zone (OIE 2016) with a radius of 10 km must be put in place around the endemic zones. This protection zone can be neglected if the border is marked by geographical barriers as high mountains or large water surfaces.
  2. Transhumance and also the movement of supers, combs, used beekeeping equipment, bees and unprocessed honeybee products across the border of the endemic area and in the protection zones should be forbidden.
  3. The use of effective traps in every single hive should be mandatory.

 

Surveillance zones and further surveillance activities

  1. The surveillance zones should be reorganised. The aim of the reorganisation is to focus the forces for monitoring on essential hot spots. At the same time beekeepers get released from ongoing restrictions concerning especially the movement of hives. These restrictions also affect the farmers, who are in need of the pollination service offered by the beekeepers. An evaluation of the costs and benefits is most likely not in favour for maintaining such restrictions for several years risking the bankruptcy of affected companies.
  2. The protection zone should be surrounded by a surveillance zone with a radius of 20 km. Significant geographical barriers such as high mountains or large water surfaces can replace the border of the surveillance zone. This area is covering possible short distance spread of Aethina tumida. The shape of the zones could be adapted according to a cost/benefit analysis.
  3. The use of traps in apiaries should be mandatory. Various measures such as chemical and physical traps, PCR of hive debris, sentinel hives and baited traps nearby honey houses are to be used to detect Aethina tumida in a complementary way.
  4. Additionally, beekeeping operations that lay within a distance of 100 km from the protection zone and sell or move bees and unprocessed bee products over long distance should be included into the monitoring. In these cases, the use of traps should be mandatory. However, they cannot be allowed to sell live bees abroad, according to Dir. 92/65/CEE.
  5. Since Aethina tumida spreads over long distances mainly by transhumance, beekeeping locations in Italy connected by transhumance (as declared to the National Beekeeping Register) should be determined as at risk zones. These may be areas where many beekeepers migrate to. Then a detailed risk based monitoring plan should be implemented to detect quickly possible spread of Aethina tumida.
  6. The beekeepers should be involved into the monitoring as main actors. Fitting the monitoring into the usual beekeeping routine can maximise the effectiveness of the monitoring. Additionally, sentinel hives or and baited traps should be set up and regularly controlled by the veterinary service.

 

Possible new outbreaks of Aethina tumida

  1. The new situation should be managed by considering all the possible activities and restrictions to be taken. In fact, only the simultaneous activation of all the main actions (immediate start of operations, availability of effective treatments, compensation for the income losses, possibilities of collaboration between all the players involved, etc.) can bring hope to get positive results.
    However, the costs and benefits and the feasibility of all planned measures in the respective area should be carefully evaluated. In particular, consider the effects of movement restrictions for beekeeping operations that rely on the movement of bees to be profitable and the possibility to compensate the income losses. Adequate funding must be available to finance the programme.
  2. Immediately enforce a provisional 10 km containment zone and implement a monitoring to define the actual extension of the infested area by using the most effective traps containing a kill substance. Evaluate quickly the result of the monitoring.
  3. The new situation should be evaluated by considering the distance to the next infested area:
    1. If the outbreak zone is adjacent to an area already declared endemic (not further away than 20 km, and no geographical barriers between them) the endemic area should get enlarged by incorporating the new outbreak zone. Move the border of the surveillance zone according to the enlargement of the endemic area. Adopt the measures described above for the enlarged endemic zone and the surveillance zone. In case the beekeeper moved some hives just before the detection of Aethina tumida, an additional monitoring should be installed also at the new apiary.
    2. In case that the outbreak is further away from the next endemic zone, a provisional containment zone should be installed. The movement of hives, bees, unprocessed bee products and used beekeeping equipment should be prohibited within the area and across the border of the containment zone. Such measures have to be combined always with compulsory treatments of every hive against SHB within the area. In case the beekeeper moved some hives just before the detection of Aethina tumida, an additional monitoring should be installed at the new apiary.
      Furthermore, the new situation should be evaluated by considering the following factors:
    • Recent history of the apiary: an investigation should be carried out to discover the contacts of the affected beekeeper.
      • Did the beekeeper migrate with his hives? Did he buy bees, unprocessed bee products or used bee equipment from a distant source? In this case the beetle might have been introduced from this source and the outbreak might be still restricted to this beekeeping operation. This justifies immediate measures to try to eradicate the pest and ideally the pest only.
      • If the beekeeper is stationary and did not buy suspicious material, Aethina tumida might have spread to his apiary from neighbouring apiaries or the environment. This might indicate already a larger infestation of the area. In this case the apiary should not be necessarily destroyed but it should be waited for the results of the immediate monitoring. For the time of the monitoring the complete beekeeping operation should be set under quarantine. Single infested hives could be treated or if necessary destroyed. All hives should be equipped with effective traps.
    • Results of the monitoring:
      • If only a few apiaries are infested, the infestation levels low and the apiaries clustered, then the implementation of all measures to eradicate the pest might be justified.
      • If the number of infested apiaries is high and/or if these apiaries show already high infestation levels and/or if those apiaries are distributed over a wider range of the area, then an eradication of the pest does not seem likely. The beetle should be declared endemic. In this case the measures described above for the enlarged endemic zone, the containment zone and the surveillance zone should get adopted.
  4. In case of an attempt to eradicate the pest, baited traps or sentinel hives should be installed at the abandoned site of destroyed apiaries in combination with baited traps. Furthermore, the hives of neighbouring apiaries should be inspected and equipped with effective traps. Since some beetles hide outside of the hives or might escape during the inspection of the hives possibly not all of them get killed when an apiary get destroyed.
  5. Any approach taken for the control of the SHB, whether eradication or containment, should be dictated by the extent of the infestation. Depending on the size and distribution of the outbreak, any shift from eradication to containment should be very swift – perhaps within just a few days of the first confirmed detection of SHB (Marris et al. 2012).
  6. In the case of an attempt to eradicate the pest, monitor the affected and neighbouring apiaries again with sentinel hives and traps within 3–6 months. If no beetles are found, rescind all restrictions. If beetles are still found, declare the zone as an endemic zone.

 

General recommendations

  1. The objective of the above measures should be to contain the pest, not to eradicate the bees or the beekeeping operations.
  2. Due to the diversity of the local situation, flexibility must be a key word to put in place the strategy to contain SHB. For example, the radius of containment and surveillance zone can be adapted. Alternatives to burning may be sulphur and freezing (Dietemann & Lerch 2015).
  3. Commercial bumble bees for pollination may need to be included in the scope of the measures.
  4. European beekeeping organizations express their wish to contribute to the solution, since they stand to benefit from the success of the control measures.
  5. Escalation procedure should call for involvement of outside experts from other countries, which have faced the situation before at an early stage irrespective of national or EU boundaries.
  6. EU and national aids for agriculture should be used to timely finance all measures, since they are designed to aid not only the beekeepers in the affected area but also to protect the beekeeping sector in the EU as a whole.

References

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