Following a request from the European Commission, the Panel on Animal Health and Welfare (AHAW) was asked to deliver a scientific opinion on the risk of entry of Aethina tumida (small hive beetle, SHB) and Tropilaelaps spp. in the European Union (EU) and the identification and evaluation of risk reduction options.
The SHB is a bee-brood scavenger of Apis mellifera (honey bee), Bombus spp. (bumble bee) and Melliponini (stingless bees). Mature larvae leave the hive and burrow in soil to pupate. This coleopteran is a flying, free-living predator that can survive and reproduce on a variety of ripe fruits, but not on vegetables, plants or flowers. Adult SHB can detect airborne volatiles produced by A. mellifera and Bombus spp. and thereby can be attracted to the odours of bees and bee products that have come into contact with bees. The pest is native to Africa but has spread to North America and Australia during the past 20 years. The larval stage of the pest is destructive to a bee population, whereas the adults have little impact. The larvae burrow through combs, eat honey and pollen, kill bee brood and defecate in honey, which subsequently ferments.
Tropilaelaps is an ectoparasite of honey bee brood (Apis spp.) and can have a short phoretic phase on honey bees. The pest cannot fly and requires honey bee brood to survive. Infestation is caused by different species of Tropilaelaps mites (including the mites Tropilaelaps clareae, T. koenigerum, T. thaii and T. mercedesae). The presumed primary hosts of T. clareae and T. koenigerum are the open-air-nesting giant wild honey bees Apis dorsata and the small cavity-nesting Asian honey bee Apis cerana. Following its host shift to A. mellifera, Tropilaelaps has spread from mainland Asia, Indonesia and the Philippines to Afghanistan, Iran, New Guinea and South Korea. The infestation and feeding activities of the Tropilaelaps mites cause honey bee brood mortality and a reduction in the lifespan of adult honey bees that survive the brood stage.
A qualitative risk assessment was performed taking into account current legislation but excluding the implementation of risk reduction options. Risk reduction options were assessed separately from the risk assessment. This approach allowed the assessment of the worst case scenario for each risk factor within a well-defined (legal) framework. The methodology used in this scientific opinion was adapted from a pest risk assessment for entry used in the field of plant health. Risk pathways were identified and scoring of the risk factors (assuming the worst case) was done by expert elicitation supported by the literature where possible, and an overall risk score for each pathway was obtained using a combination matrix that is used in the animal health risk assessment field. The identification and evaluation of risk reduction options was performed separately from the risk assessment for entry. After identifying possible risk reduction options on entry, each option was evaluated by scoring its effectiveness and technical feasibility and estimating the uncertainty of these scores.
Four risk questions were addressed and the conclusions are described below:
The risk of introduction, limited to entry, of SHB and Tropilaelaps into the EU through importation from third countries of live queen bees, queen bumble bees (Bombus spp.), bumble bee colonies and bee products destined to be used in apiculture
- A. mellifera queens. There is a moderate risk of SHB entry via intentional import of honey bee queens. This is substantiated by the rapid detection and adequate reaction which prevented the establishment of SHB when it once entered into the risk assessment area. For Tropilaelaps, the risk ofentry via intentional import of honey bee queens is low since this pest is a parasite of honey bee brood and has only a short phoretic phase on honey bees.
- Bombus spp. queens. Bumble bees are a less likely source of SHB entry than honey bees since there are no field data on the biological association of SHB with Bombus spp. at present. Entry of Tropilaelaps spp. via imports of Bombus spp. queen bees was not considered a risk pathway since this pest has never been reported with bumble bees.
- A. mellifera swarms/colonies and Bombus spp. colonies. The risk of pestentry via import of swarms and/or colonies is high, however, the risk of entry of SHB and Tropilaelaps into the risk assessment area is low and moderate, respectively, because import of swarms and colonies is not permitted according to the actual legislation.
- Bee products. The risk of entry via bee products to be used in apiculture is high for SHB since the pest is attracted to these products and no risk reduction options were taken into account during the risk assessment. For Tropilaelaps, the risk of entry via this pathway is moderate. Honey bee brood can be infested by Tropilaelaps but it is unlikely that bee brood will be introduced into an apiary and that the pest will leave the consignment because of its limited mobility.
- Accidental bee import (unintended presence of bees in a non-bee consignment) is associated with a high risk of entry for both pests since an infested consignment might not be detected.
The risk of introduction of the SHB and Tropilaelaps into the EU from neighbouring countries, especially through the natural movements of live bees and of the SHB
At present, the risk of SHB and Tropilaelaps entry by natural means and/or flight is moderate and low, respectively, given that both pests are not reported in countries neighbouring the risk assessment area. If either pest were to be present or established in neighbouring countries, there would be a high risk that SHB and Tropilaelaps would reach suitable hosts in the risk assessment area.
The risk of introduction of SHB and Tropilaelaps into the EU through importation from third countries of products other than bee products (e.g., fruits, vegetables, other possible vectors and fomites, etc.)
- For SHB, non-bee products that could be at risk for entry into the risk assessment area are imported ripe fruits, used beekeeping equipment, soil as contaminant (e.g., attached to the roots of plants for planting) and soil as plant substrate (e.g., potted plants) since import of soil itself is not permitted. The risk of SHB entry through import of these commodities is moderate, mainly because consignments of these products have a low level of infestation and/or have a low to moderate trade volume. Most types of imported fruit are not considered to be at risk since they are shipped in an unripe stage.
- For Tropilaelaps, used bee equipment is the only non-bee product at risk for entry into the risk assessment area. The risk is low owing to a low probability of pest survival during transport in the absence of honey bee brood and/or adults.
The risk-mitigating factors that have proven to be or that could potentially be effective in ensuring safe international trade as regards the transmission of SHB and Tropilaelaps in bees and their products
Risk reduction options with a high effectiveness, high technical feasibility and low uncertainty are those most likely to prevent SHB and Tropilaelaps entry into the risk assessment area and were identified in all risk pathways except ‘accidental import of bees’ and ‘dispersal of the pest via natural means and/or flight’.
Risk reduction options likely to reduce the risk of SHB entry into the risk assessment area are:
- For the importation of A. mellifera and Bombus spp. queens, introduction of an active surveillance system by an authority in a third country. Such a system would issue a certificate of pest freedom in the specific zone, ensure pest freedom of a consignment before shipment and prevent escape of the pest from the consignment during transport.
- For importation of swarms and colonies, no likely risk reduction is available during transport or at the border whereas the risk of SHB entry via this pathway is high. Therefore, the EU legislation does not primarilly permit import of swarms and colonies into the risk assessment area.
- For the importation of bee products to be used in apiculture, beekeeping equipment and soil (as a contaminant and in potted plants), application of treatments to eradicate the pest in third countries, during transport and at the border. Also likely to reduce the risk of SHB entry is the introduction of an active surveillance system by an authority in a third country that provides a certificate of pest freedom in the specific zone and which ensures pest freedom of a consignment before shipment (not applicable for soil).
- For import of non-bee products, the only risk reduction option likely to reduce the risk of SHB entry is the introduction of an active surveillance system by an authority in a third country that provides a certificate of pest freedom in the specific zone.
For Tropilaelaps, there are two risk reduction options likely to reduce the risk of pestentry into the risk assessment area and which can be applied in all risk pathways, except the pathways ‘accidental honey bee import’ and ‘dispersal of Tropilaelaps by flying bees’:
- Entry of Tropilaelaps is likely to be prevented by applying a biological treatment throughout the risk pathway. In the case of queens, this can be achieved by preventing the consignment without honey bee brood for a minimum of 21 days. For importation of used beekeeping equipment or bee products to be used in apiculture, this can be achieved by preventing contact with honey bee brood and/or adults for a minimum of 21 days.
- Introduction of an active surveillance system by an authority in a third country that provides a certificate of pest freedom in the specific zone is also likely to be reduce the risk of pest entry.
Although the risk reduction options were individually evaluated, it is clear that the risk of pest entry via most risk pathways will be further reduced when different risk reduction options are applied throughout the pathway. The likely options are mainly included in the current EU legislation or mentioned in World Organisation for Animal Health (OIE) guidelines. However, the risk pathway ‘accidental import of bees’ requires special attention since it is associated with high risk for both SHB and Tropilaelaps entry and no likely risk reduction option can be applied.
Based on the results of the pest risk assessment and the evaluation of risk reduction options, the AHAW Panel identified a need for validated rapid detection methods for SHB and Tropilaelaps and a need for handling and sampling of imported bees in an insect-proof environment at the designated place of final destination. Education and training of people involved in beekeeping, or trade in or transport of bees, by improving awareness, skills and expertise, could help to monitor the distribution of SHB and Tropilaelaps in third countries and to prevent entry of both pests into the risk assessment area. It is recommended that research be carried out to ascertain the risk of SHB entry via products such as ripe fruits and soil associated with plants as well as the harmful effects of Tropilaelaps infestation. At present, there are only limited data available on the harmful effects of Tropilaelaps infestation and the current view is at least partially based on extrapolations from Varroa infestations.