The European Commission requested scientific advice from the European Food Safety Authority (EFSA) on the small hive beetle (SHB, Aethina tumida), a bee-brood scavenger of Apis mellifera (honey bee), Bombus spp. (bumblebee) and Melliponini (stingless bees). In the first Term of Reference (TOR), EFSA was asked to assess the risk of survival, spread and establishment of SHB in and from Calabria and Sicily into other parts of Italy and the EU. The outbreak in Calabria and Sicily is described based on the data provided by the Italian authorities. To model the spread of SHB, two separate but similar mathematical models were constructed to simulate the dispersal from infested to non-infested apiaries. The models allow for the spread of SHB either solely due to proximity to infested apiaries (distance-only model) or due to proximity and through beekeepers infesting their other apiaries by unintentional transfer of the beetle (distance and ownership model). Movement of an infested hive would facilitate a rapid spread of SHB over large distances. Modelling SHB spread in the absence of movement of hives suggested that with natural spread alone it will take more than 100 years for the beetle to move northwards to Abruzzo from Calabria (around 250 km). A model considering the ownership of multiple apiaries per beekeeper indicates that spread would be 10 times faster. The new SHB detections in Calabria in September 2015 corroborate the modelling, which has indicated that the infestation has not been eradicated.
Opportunity maps based on calculated soil temperature at 20 cm depth indicate that, once introduced, the SHB could complete its life cycle in all the EU Member States (MS) between May and September. However, if temperatures are below 10°C, adult SHB can survive and overwinter in the honey bee colony cluster. The probability of SHB introduction from Italy to other MS is mainly dependent on the sensitivity of the test to detect SHB in traded consignments and the number of shipments arriving in a country in a given time period. Implementing sensitive SHB testing in consignments could decrease the probability of SHB introduction around 20-fold compared with absence of SHB testing. As SHB prevalence in an area depends on the control measures in place, the probability of introduction will increase when SHB prevalence increases, and could be from 2.5 up to 7 times higher if no SHB testing is in place. The lack of reliable information on the actual SHB prevalence in southern Italy, the sensitivity of the test used and number of consignments shipped between MS did not allow concrete estimations reflecting the field situation.
The second TOR requested that EFSA assess risk-mitigating factors that could potentially be effective in ensuring safe intra-EU trade of live bees, apiculture products and by-products in terms of preventing the transmission of SHB. Based on the scientific literature and qualitative evaluation by experts, detection of SHB by visual inspection and subsequent delivery of a health certificate, within 24 hours before dispatch, has been found to be highly effective and feasible for consignments of queen bees only. It is still impossible to obtain a complete dataset on European beekeeping because of the high variability of colony registration requirements in the MS. Furthermore, it is concluded that use of fine mesh with maximum 2 mm pore size to avoid contamination during transport is highly effective and feasible for consignments of bees, bee products to be used in apiculture, non-extracted comb honey and used beekeeping equipment. However, feasibility decreases as a function of the size of the consignment. Currently, implementation of precautions to prevent contamination of a shipment is required only in the case of import from third countries. For consignments of bee products to be used in apiculture, freezing and desiccation are highly effective and feasible in reducing the risk of SHB transmission. For consignments of used beekeeping equipment, freezing, heating and desiccation are highly effective in reducing the risk of SHB transmission. The feasibility depends on the size of the shipment and on facilities available. The assessment assumed that visual inspection is perfectly implemented, although this might not always be the case in practice. Therefore, it is recommended that the SHB status of the area of origin of consignments be taken into consideration when issuing health certificates and that visual inspection of bee consignments undergoing intra-EU movement be strengthened, as it is already done in the case of import from third countries. The availability of a register of the location of apiaries and number of hives within an area together with tracking information on the travel route of shipments would be essential to facilitate epidemiological investigations in the event of an outbreak. Moreover, even in the absence of a national registration system, it is recommended that beekeepers keep records of their bee movements to facilitate investigation of outbreaks. Finally, making more use of fine mesh (with maximum 2 mm pore size) for intra-EU trade of commodities could reduce the risk of SHB transmission via consignments.
The third TOR requested EFSA to assess the risk mitigating factors and methods in apiaries, alternative to currently employed complete destruction of the apiary and additional risk mitigating factors that may be applied in controlled environments for queen producing. Based on the scientific literature and experience of outbreaks, it was concluded that visual inspection is the most frequently used method to detect SHB in apiaries and, depending on the expertise of the inspector and the rigour of the inspection process, it can identify not only the pest in its different life stages, but also damage caused by the pest. Traps and polymerase chain reaction (PCR) analysis of hive debris are other methods that can be used in apiaries in addition to visual inspection, although the PCR method needs to be validated in field conditions to better evaluate its performance. Good honey house hygiene and good beekeeping practices are the most important measures to control SHB in an infested area where eradication is no longer the objective, given that no approved veterinary medicine is available in the EU. Based on experience in Australia, Canada and the USA, traps could be used to reduce the SHB population in infested areas. No specific control measures to keep honey bee queen production free from SHB in an infested area are available, and there is no EU legislation in place regarding movement control of honey bees, bumblebees or commodities in a SHB-infested area. Soil treatment with pyrethroids to control SHB should be applied only in the event of comb damage, and exposure of non-target species to pyrethroids should be avoided. It is also recommended that restrictions on the movement of honey bees, bumblebees and commodities from infested to noninfested areas be maintained until SHB is eradicated in order to prevent spread of the pest.
The fourth TOR requested EFSA to review the surveillance in assessing an area’s freedom from SHB, including the size (radius of) of the areas to be surveyed, in order to provide solid bases for regionalisation policy. According to modelling that took into account inspection and mitigation measures implemented in Italy, including establishing a protection zone of 20 km radius, reducing the surveillance zone radius from 100 km to 50 km will at least double the probability of SHB escaping from that surveillance zone, from 0.025 to 0.05. The World Organisation for Animal Health (OIE) requirement to implement a 5-year monitoring programme to substantiate SHB freedom is based on the current knowledge of the biological characteristics of the pest. However, any recommendation on the duration of such a monitoring programme is subject to high uncertainty because relatively few data are available. Passive surveillance is implemented in all MS as SHB detection is notifiable. Guidelines on surveillance strategies have been published by the European Reference Laboratory on Honey Bee Health. Training of beekeepers and veterinary inspectors is recommended as it will facilitate rapid SHB detection.
The fifth TOR requested EFSA to assess the susceptibility of kept bumblebees (Bombus terrestris) to SHB or their capability to spread SHB. A field experiment found natural infestation of commercial bumblebee B. impatiens colonies placed next to SHB-infested honey beehives. However, there are no published data on SHB infestation in natural bumblebee colonies. Food resources and conditions in bumblebee colonies are attractive to SHB and suitable for its development. Therefore, the possibility that bumblebee colonies act as a reservoir for SHB cannot be excluded. Studies of the capacity of B. terrestris (occurring in Europe) to act as an SHB host, are needed since data are currently available only for B. impatiens. Furthermore, kept bumblebee boxes should be destroyed after the pollination service.