added 2 research items
Cuticular hydrocarbons (CHCs) play key olfactory roles in insect mating, and can therefore be used for pest control. However, the CHC profiles of adult small hive beetles (SHB), Aethina tumida, are currently unknown, even though this widespread invasive species threatens agriculture and wild bee populations. Here we show that CHC profiles can differ between SHB males and females, as well as their mating statuses. In the laboratory, SHB were reared individually and then kept singly or in mixed groups of males and females until sexual maturity at day 10. Then, CHC profiles were compared between the six groups (virgin 1 and 10 days old females, mated 10 days old females, virgin 1 and 10 days old males, and mated 10 days old males). The data show largely homogenous CHC profiles, with no substance being specific to males. However, Hexahydropyridine,1-methyl-4-[4,5-dihydroxyphenyl] was only detected in female SHBs and 2′-Hydroxypropiophenone, TMS derivative was only detected in 10 days old virgin females, and 5-Cyclohexyl-1-pentene was exclusively found in mated beetles, regardless of sex or age. The biological activity of these candidates needs to be confirmed. Given that they constitute olfactory cues involved in mating, this would offer a promising avenue for sustainable pest control of SHB, enabling for the first time to protect wild bee populations.
The small hive beetle (SHB), Aethina tumida, a parasite of honey bees is endemic to Sub-Saharan Africa and has become a global invasive pest. Adequate surveillance methods based on trapping methods need testing and verification of their efficacy. We tested the efficacy of top frame supplied cardboard traps. The efficacy was extremely low (0.9%) and significantly less effective than bottom board placed traps.
Invasive species are a major driver of ecological and environmental changes that affect human health, food security, and natural biodiversity. The success and impact of biological invasions depend on adaptations to novel abiotic and biotic selective pressures. However, the molecular mechanisms underlying adaptations in invasive parasitic species are inadequately understood. Small hive beetles, Aethina tumida, are parasites of bee nests. Originally endemic to sub-Saharan Africa, they are now found nearly globally. Here, we investigated the molecular bases of the adaptations to novel environments underlying their invasion routes. Genomes of historic and recent adults A. tumida from both the endemic and introduced ranges were compared. Analysis of gene-environment association identified 3049 candidate loci located in 874 genes. Functional annotation showed a significant bias toward genes linked to growth and reproduction. One of the genes from the apoptosis pathway encodes an "ecdysone-related protein," which is a crucial regulator in controlling body size in response to environmental cues for holometabolous insects during cell death and renewal. Genes whose proteins regulate organ size, ovary activation, and oviposition were also detected. Functions of these enriched pathways parallel behavioral differences between introduced and native A. tumida populations, which may reflect patterns of local adaptation. The results considerably improve our understanding of the underlying mechanisms and ecological factors driving adaptations of invasive species. Deep functional investigation of these identified loci will help clarify the mechanisms of local adaptation in A. tumida.
Invasive species are of major concern globally because they affect human health and food security. To limit their spread and impact, locally and internationally concerted efforts are required. This holds true for invasive pests of pollinators, such as small hive beetles (Aethina tumida, Coleoptera: Nitidulidae), thus prompting the initiation of a COLOSS Task Force (TF) on this beetle.
Cuticular hydrocarbons (CHCs) cover insects’ bodies and play important roles in chemical communication, including nestmate recognition, for social insects. To enter colonies of a social host species, parasites may acquire host-specific CHCs or covertly maintain their own CHC profile by lowering its quantity. However, the chemical profile of small hive beetles (SHBs), Aethina tumida, which are parasites of honey bee, Apis mellifera, colonies, and other bee nests, is currently unknown. Here, adults of SHB and honey bee host workers were collected from the same field colonies and their CHC profiles were analysed using GC-MS. The chemical profiles of field-sampled SHBs were also compared with those of host-naive beetles reared in the laboratory. Laboratory-reared SHBs differed in their CHC profiles from field-sampled ones, which showed a more similar, but ten-fold lower, generic host CHC profile compared to host workers. While the data confirm colony-specific CHCs of honey bee workers, the profile of field-collected SHBs was not colony-specific. Adult SHBs often commute between different host colonies, thereby possibly preventing the acquisition of a colony-specific CHC profiles. An ester was exclusive to both groups of SHBs and might constitute an intraspecific recognition cue. Our data suggest that SHBs do not use any finely tuned chemical strategy to conceal their presence inside host colonies and instead probably rely on their hard exoskeleton and defence behaviours.
Small hive beetles (SHB, Aethina tumida Murray, Coleoptera: Nitidulidae) are parasites of social bee colonies endemic to sub-Saharan Africa and have become an invasive species. Even though the global spread of SHB seems inevitable, the origin of novel introductions and their impact on new host populations need to be investigated to foster mitigation. Here, we report of SHBs from China and use COI gene sequencing to trace their origin. Since July 2018, beetle infestations of Eastern (Apis cerana) and Western (Apis mellifera) honey bee colonies with clinical symptoms were repeatedly reported from two Chinese provinces. These infestations apparently had a severe impact on A. cerana. Using morphometrics, genetics and clinical symptoms in the field, the beetles were confirmed to be A. tumida. The DNA sequences suggest an introduction from a yet unidentified African source similar to the Philippines, but very different to any other previously reported SHB haplotypes. The establishment of SHB in China underlines the need to limit novel introductions. Given that Eastern honey bees and possibly other Apis spp. are susceptible to SHB infestations, our findings highlight the need for adequate protection measures of endemic Asian honey bees.
The small hive beetle, Aethina tumida Murray, is an invasive pest that has spread globally. Western honey bees, Apis mellifera Linnaeus (Hymenoptera: Apidae), are considered the most important host and infestations can lead to collapse of colonies. Larvae feed on honey, pollen, and brood inside the hive and leave the hive as postfeeding wandering larvae to pupate in the surrounding soil. Other host species include bumble bees, stingless bees, and solitary bees, all of which can facilitate small hive beetle reproduction and are used for greenhouse crop pollination worldwide. Here, we investigated if small hive beetles can complete their life cycle when soil is absent by pupating in plant root-supporting substrates commonly used in greenhouses. Wandering small hive beetle larvae were introduced into containers with coconut fiber, perlite, a mixture of both and stone wool substrates to investigate pupation success and development time. Sand was used as control substrate. In all but one substrate (perlite), small hive beetles developed into adults equally well as they did in the sand. Development time ranged between 23 and 37 d and was not different from that of the control. We showed that small hive beetles can pupate in greenhouse substrates. This could constitute a problem for greenhouse pollination as well as it could facilitate small hive beetle survival in areas which otherwise would be deemed unsuitable or marginal environments for small hive beetles to become established. Our study highlights the opportunistic nature of the small hive beetle as an invasive species.
Olfaction is key to many insects. Odorant receptors (ORs) stand among the key chemosensory receptors mediating the detection of pheromones and kairomones. Small hive beetles (SHBs), Aethina tumida, are parasites of social bee colonies and olfactory cues are especially important for host finding. However, how interactions with their hosts may have shaped the evolution of ORs in the SHB remains poorly understood. Here, for the first time, we analyzed the evolution of SHB ORs through phylogenetic and positive selection analyses. We then tested the expression of selected OR genes in antennae, heads, and abdomens in four groups of adult SHBs: colony odor-experienced/-naive males and females. The results show that SHBs experienced both OR gene losses and duplications, thereby providing a first understanding of the evolution of SHB ORs. Additionally, three candidate ORs potentially involved in host finding and/or chemical communication were identified. Significantly different downregulations of ORs between the abdomens of male and female SHBs exposed to colony odors may reflect that these expression patterns might also reflect other internal events, e.g., oviposition. Altogether, these results provide novel insights into the evolution of SHB ORs and provide a valuable resource for analyzing the function of key genes, e.g., for developing biological control. These results will also help in understanding the chemosensory system in SHBs and other beetles.
Starvation resistance, or the ability to survive periods without food, can shed light on selection pressure imposed by food scarcity, including chances to invade new regions as a result of human transport. Surprisingly, little information is known about starvation resistance for invasive insect species. Given that native and invasive populations differ in starvation resistance, this would suggest different selection scenarios and adaptive shifts fostering invasion success. Here, we show striking differences in starvation resistance of adult small hive beetles Aethina tumida (SHB) between native and invasive populations. In the laboratory, starvation resistance of freshly emerged laboratory‐reared and field‐collected adult females and males was evaluated in the beetle's native African range and in their invasive North American range. SHB in their native African range survived longer than SHB in their invasive North American range. Across ranges, females survived longer than males. Field‐collected SHB survived in Africa longer than freshly emerged ones, but not in the invasive range. This suggests no selection for starvation resistance in the invasive range, possibly due to differences between African and European‐derived honey bee hosts facilitating a trade‐off scenario between reproduction and starvation resistance. The ability of adult females to survive up to two months without food appears to be one factor contributing to the invasion success of this species. Assuming food availability is usually high in the invasive ranges, and trade‐offs between starvation resistance and fecundity/reproduction are common, it seems as if selection for starvation resistance during transport could set up potential trade‐offs that enhance reproduction after invasion. It would be interesting to see if this is a possible general pattern for invasive insect species.
Climate change and biological invasions are two major global environmental challenges. Both may interact, e.g. via altered impact and distribution of invasive alien species. Even though invasive species play a key role for compromising the health of honey bees, the impact of climate change on the severity of such species is still unknown. The small hive beetle (SHB, Aethina tumida, Murray) is a parasite of honey bee colonies. It is endemic to sub-Saharan Africa and has established populations on all continents except Antarctica. Since SHBs pupate in soil, pupation performance is governed foremost by two abiotic factors, soil temperature and moisture, which will be affected by climate change. Here, we investigated SHB invasion risk globally under current and future climate scenarios. We modelled survival and development time during pupation (=pupal performance) in response to soil temperature and soil moisture using published and novel experimental data. Presence data on SHB distribution were used for model validation. We then linked the model with global soil data in order to classify areas (resolution: 10 arcmin; i.e. 18.6 km at the equator) as unsuitable, marginal and suitable for SHB pupation performance. Under the current climate, the results show that many areas globally yet uninvaded are actually suitable, suggesting considerable SHB invasion risk. Future scenarios of global warming project a vehement increase in climatic suitability for SHB and corresponding potential for invasion, especially in the temperate regions of the Northern hemisphere, thereby creating demand for enhanced and adapted mitigation and management. Our analysis shows, for the first time, effects of global warming on a honey bee pest and will help areas at risk to prepare adequately. In conclusion, this is a clear case for global warming promoting biological invasion of a pest species with severe potential to harm important pollinator species globally.
International trade can facilitate biological invasions, but the possible role of beeswax trade for small hive beetles (SHBs), Aethina tumida Murray (Coleoptera: Nitidulidae) is poorly understood. SHBs are parasites of social bee colonies native to sub-Saharan Africa and have become an invasive species. Since 1996, SHBs have established in all continents except Antarctica. Here, we combine mitochondrial DNA analyses (COI gene, N = 296 SHBs, 98 locations) with previously published beeswax trade data (FAO) for 12 confirmed SHB invasions. Our genetic data confirm previous findings and suggest novel SHB African origins. In nine out of 12 invasion cases, the genetic and beeswax trade data match. When excluding one confirmed pathway (bee imports) and two cases, for which no FAO data were available, the genetics and beeswax trade data consistently predict the same source. This strongly suggests that beeswax imports from Ethiopia, South Africa, Tanzania and the USA, respectively, have mainly been responsible for the past invasion success of this beetle species. Adequate mitigation measures should be applied to limit this key role of beeswax imports for the further spread of SHBs. Combining genetics with trade data appears to be a powerful tool to better understand and eventually mitigate biological invasions.
Invasive species may exploit a wide range of food sources, thereby fostering their success and hampering mitigation, but the actual degree of opportunism is often unknown. The small hive beetle (SHB), Aethina tumida, is a parasite of honeybee colonies endemic to sub‐Saharan Africa. SHBs have now spread on all habitable continents and can also infest colonies of other social bees. To date, the possible role of solitary bee nests as alternative hosts is unknown. Similarly, flowers as possible alternative food sources are not well understood. Here, we show that SHBs can complete an entire life cycle in association with nests of solitary bees Megachile rotundata. The data also show that flowers can serve as alternative food sources. These results support the opportunistic nature of this invasive species, thereby generating further obstacles for mitigation efforts in the field. It also suggests that SHB invasions may result in more serious consequences for endemic bee fauna than previously thought. This provides further motivation to slow down the global spread of this pest, and to improve its management in areas, where it is established.
The sex ratio of sexually reproducing animal species tends to be 1:1, which is known as Fisher's principle. However, differential mortality and intraspecific competition during pupation can result in a biased adult sex ratio in insects. The female-biased sex ratio of small hive beetles (SHBs) is known from both laboratory and field studies, but the underlying reasons are not well understood. Here, we used laboratory mass and individual pupation to test if differential mortality between sexes and/or intraspecific interactions can explain this sex ratio. The data show a significant female-biased adult sex ratio in both mass and individual rearing, even when assuming that all dead individuals were males. Our results therefore suggest that neither differential mortality during pupation nor intraspecific interactions are likely to explain the female-biased sex ratio of freshly emerged adult SHBs. We regard it as more likely that either competition during the larval feeding stage or genetic mechanisms are involved. In addition, we compared our data with previously published data on the sex ratio of both freshly emerged and field-collected SHBs to investigate possible gender differences in adult longevity. The data show a significantly greater female bias in the sex ratio upon emergence, compared to field-collected SHBs, suggesting that adult females have a shorter longevity.
Small hive beetles (SHBs) are parasites of social bee colonies endemic to sub-Saharan Africa and have become a widespread invasive species. In the new ranges, SHBs can cause damage to apiculture and wild bees. Although the further spread seems inevitable, eradication of new introductions and containment of established ones are nevertheless urgently required to slow down the invasion speed until better mitigation options are available. However, at present there is no adequate action plan at hand. Here, we propose to take advantage of SHB invasion history and biology to enrol a feasible plan involving all stakeholders. Raising awareness, education and motivation of stakeholders (incl. adequate and timely compensation of beekeepers) is essential for success. Moreover, sentinel apiaries are recommended in areas at risk, because early detection is crucial for the success of eradication efforts. Given that introductions are detected early, SHB eradication is recommended, incl. destruction of all infested apiaries, installation of sentinel colonies to lure escaped SHBs and a ban on migratory beekeeping. If wild perennial social bee colonies are infested, eradication programs are condemned to fail and a strategic switch to a containment strategy is recommended. Containment includes adequate integrated pest management and a strict ban on migratory beekeeping. Despite considerable gaps in our knowledge of SHBs, the proposed action plan will help stakeholders to slow down the global spread of SHBs.
Small hive beetles (SHBs) are parasites of social bee colonies endemic to sub-Saharan Africa and have become a widespread invasive species. In the new ranges, SHBs can cause damage to apiculture and wild bees. Although the further spread seems inevitable , eradication of new introductions and containment of established ones are nevertheless urgently required to slow down the invasion speed until better mitigation options are available. However, at present there is no adequate action plan at hand. Here, we propose to take advantage of SHB invasion history and biology to enrol a feasible plan involving all stake-holders. Raising awareness, education and motivation of stakeholders (incl. adequate and timely compensation of beekeepers) is essential for success. Moreover, sentinel apiaries are recommended in areas at risk, because early detection is crucial for the success of eradication efforts. Given that introductions are detected early, SHB eradication is recommended, incl. destruction of all infested apiaries, installation of sentinel colonies to lure escaped SHBs and a ban on migratory beekeeping. If wild perennial social bee colonies are infested, eradication programs are condemned to fail and a strategic switch to a containment strategy is recommended. Containment includes adequate integrated pest management and a strict ban on migratory beekeeping. Despite considerable gaps in our knowledge of SHBs, the proposed action plan will help stakeholders to slow down the global spread of SHBs.
Background The small hive beetle (Aethina tumida, ATUMI) is an invasive parasite of bee colonies. ATUMI feeds on both fruits and bee nest products, facilitating its spread and increasing its impact on honey bees and other pollinators. We have sequenced and annotated the ATUMI genome, providing the first genomic resources for this species and for the Nitidulidae, a beetle family that is closely related to the extraordinarily species-rich clade of beetles known as the Phytophaga. ATUMI thus provides a contrasting view as a neighbor for one of the most successful known animal groups. Results We present a robust genome assembly and a gene set possessing 97.5% of the core proteins known from the holometabolous insects. The ATUMI genome encodes fewer enzymes for plant digestion than the genomes of wood-feeding beetles, but nonetheless shows signs of broad metabolic plasticity. Gustatory receptors are few in number compared to other beetles, especially receptors with known sensitivity (in other beetles) to bitter substances. In contrast, several gene families implicated in detoxification of insecticides and adaptation to diverse dietary resources show increased copy numbers. The presence and diversity of homologs involved in detoxification differs substantially from the bee hosts of ATUMI. Conclusions Our results provide new insights into the genomic basis for local adaption and invasiveness in ATUMI, and a blueprint for control strategies that target this pest without harming their honey bee hosts. A minimal set of gustatory receptors is consistent with the observation that, once a host colony is invaded, food resources are predictable. Unique detoxification pathways and pathway members can help identify which treatments might control this species even in the presence of honey bees, which are notoriously sensitive to pesticides.
• Small hive beetles (SHBs) Aethina tumida are parasites of honeybee colonies native to sub‐Saharan Africa and have become an invasive species. • SHB mass reproduction can destroy entire host colonies, although it is very rare in populations of African honeybee subspecies. However, there are no data available on SHB cryptic low‐level reproduction in African host colonies. • In the present study, we dissected entire African honeybee (Apis mellifera adansonii) colonies in Benin. • The data obtained show that nondestructive, low‐level SHB reproduction can be very common in Africa and is sufficient to explain local infestation levels of host colonies with adult SHBs.
In order to investigate the possible infection of Nosema ceranae in small hive beetle (SHB), Aethina tumida, in 2017, beetle specimens were sampled in Gainesville (Florida). By Real-Time PCR (qPCR), using previously developed primers based on the 16S rRNA gene, N. ceranae was detected in 7 out of 10 SHB specimens, proving that the microsporidia can be transmitted by the alien beetle. This is the first report of N. ceranae infection in A. tumida, although evaluated on a few specimens. © 2018, INRA, DIB and Springer-Verlag France SAS, part of Springer Nature.
Small hive beetle (SHB) is an invasive species in populations of European honeybee subspecies, but underlying reasons for SHB success are not well understood. African and European honeybee, Apis mellifera, subspecies differ in absconding, and small hive beetle, greater wax moth (GWM) and ants all can exploit abandoned nests. However, the impact of host absconding on SHB reproduction and the role of GWM and ants as competitors are not known. Here, we conducted a survey in South Africa, Australia and the USA to evaluate SHB and GWM reproduction and foraging by ants in abandoned honeybee colonies. While the impact of competing ants and GWM was not significant, the data show higher SHB reproduction in abandoned nests of European honeybees compared to African ones, but less for GWM. The positive correlation between abandoned protein sources (brood, pollen) on SHB reproduction suggests that the less efficient preparation for absconding by European honeybee subspecies combined with their large colony sizes is a key factor for the invasion success of SHB.
Small hive beetles (SHBs) are parasites of social bee colonies endemic to Africa and have become a widely distributed invasive species. Damage to colonies in the new ranges seems to be governed by higher infestation levels, but the factors underlying SHB numbers are poorly understood. Since SHBs pupate in the soil outside of colonies, local temperature and humidity are likely to underlie infestation levels. Here, we conducted a survey in Nigeria of 82 honey bee colonies, Apis mellifera adansonii (26 apiaries, 14 States), in both forest and savannah with a range of temperatures and precipitation. We recorded significantly higher SHB infestation levels in forests compared to savannah. While there was no significant correlation between local temperature and SHB infestation levels, a significant positive correlation was found between local rainfall and SHB numbers in colonies. Under the temperature conditions of the study region, precipitation and a forest cover appear to impact SHB infestation levels of honey bee colonies. Our data suggest that new SHB distribution ranges with both forests and high precipitation will be especially at risk.
Small hive beetles (SHBs) are parasites of social bee colonies endemic to Africa and have become a widely distributed invasive species. Damage to colonies in the new ranges seems to be governed by higher infestation levels, but the factors underlying SHB numbers are poorly understood. Since SHBs pupate in the soil outside of colonies, local temperature and humidity are likely to underlie infestation levels. Here, we conducted a survey in Nigeria of 82 honey bee colonies, Apis mellifera adansonii (26 apiaries, 14 states), in both forest and savannah with a range of temperatures and precipitation. We recorded significantly higher SHB infestation levels in forests compared to savannah. While there was no significant correlation between local temperature and SHB infestation levels, a significant positive correlation was found between local rainfall and SHB numbers in colonies. Under the temperature conditions of the study region, precipitation and a forest cover appear to impact SHB infestation levels of honey bee colonies. Our data suggest that new SHB distribution ranges with both forests and high precipitation will be especially at risk.
Currently, the most used strategy for monitoring invasion of SHB consists of using sentinel colonies (three to five frames of bees) as trap hives These hives are placed around high risk areas (e.g., sea ports) and checked regularly for the presence of SHBs (see Neumann et al., 2016, for a list of countries implementing this strategy). Additionally, in-hive SHB traps can be used to make capturing SHBs easier. Visual screening of colonies is currently considered the most effective diagnostic method for SHB, specifically when looking for low numbers of individuals in an early stage of invasion . Furthermore, this can be applied by various stakeholders (e.g., beekeepers, veterinarians) as well and included in monitoring strategies. Visual screening for SHB does, however, require knowledge of beetle behaviour. Here we provide tips for screening colonies for SHBs. First, the focus is on beetle behaviour and appearance (1–4), followed by notes to the observer (5–9).
Small hive beetles (SHBs), Aethina tumida, are parasites of social bee colonies native to sub-Saharan Africa and have become an invasive species at a global scale. Reliable Polymerase Chain Reaction (PCR) diagnosis of this mandatory pest is required to limit its further spread and impact. Here, we have developed SHB primers, which amplify for 10 native African locations and 10 reported introductions, but not for three closely related species (Aethina concolor, Aethina flavicollis, and Aethina inconspicua). We also show that adult honey bee workers can be used as matrices for PCR-based detection of SHBs. The sensitivity of this novel method appears to be 100%, which is identical to conventional visual screenings. Furthermore, the specificity of this novel approach was also high (90.91%). Since both sensitivity and specificity are high, we recommend this novel PCR method and the new primers for routine surveillance of hives in high-risk areas.
Small hive beetles (SHBs), Aethina tumida (Coleoptera: Nitidulidae), are parasites and scavengers of honey bee colonies in their endemic range in sub-Saharan Africa as well as in their new distribution range. Even though flowering plants may in principle also serve as a food for SHBs, evidence so far suggest that this beetle is unlikely to visit flowers. However, field data remain scarce calling for more efforts to investigate the potential of flowers as reservoirs for this pest of social bees. Here, we conducted extensive field surveys of flowering plants in Australia. Despite the very large sample size, not a single adult SHB was found on any of the flowers. This is in line with an earlier field survey. Since SHBs were also absent from fruits in other surveys, it appears as if alternative food sources outside of bee colonies are of minor importance only for SHBs.
Workers from social insect colonies use different defence strategies to combat invaders. Nevertheless, some parasitic species are able to bypass colony defences. In particular, some beetle nest invaders cannot be killed or removed by workers of social bees, thus creating the need for alternative social defence strategies to ensure colony survival. Here we show, using diagnostic radioentomology, that stingless bee workers (Trigona carbonaria) immediately mummify invading adult small hive beetles (Aethina tumida) alive by coating them with a mixture of resin, wax and mud, thereby preventing severe damage to the colony. In sharp contrast to the responses of honeybee and bumblebee colonies, the rapid live mummification strategy of T. carbonaria effectively prevents beetle advancements and removes their ability to reproduce. The convergent evolution of mummification in stingless bees and encapsulation in honeybees is another striking example of co-evolution between insect societies and their parasites.
Worker honeybees (Apis mellifera capensis) encapsulate the small hive beetle (Aethina tumida), a nest parasite, in propolis (tree resin collected by the bees). The encapsulation process lasts 1-4 days and the bees have a sophisticated guarding strategy for limiting the escape of beetles during encapsulation. Some encapsulated beetles died (4.9%) and a few escaped (1.6%). Encapsulation has probably evolved because the small hive beetle cannot easily be killed by the bees due to its hard exoskeleton and defensive behaviour.
The small hive beetle (Aethina tumida, SHB) is a common honey bee (Apis mellifera) parasite in Africa that causes little damage to strong colonies (Lundie, 1940). However, it is a serious threat in the Western Hemisphere where the beetle has been introduced recently (Elzen et al., 1999) and where host colonies lack the behavioural resistance mechanisms of African honey bees (Neumann et al., 2001). Captive breeding of this parasite is an important research technique to produce SHB under controlled conditions for experiments. Here we report on a simple technique for rearing SHB in the laboratory
The small hive beetle, Aethina tumida Murray, 1867 (Coleoptera: Nitidulidae), is endemic to sub-Saharan Africa (El-Niweiri et al., 2008). It has recently become an invasive species in populations of European derived honey bees, Apis mellifera, (Hassan and Neumann, 2008; Neumann and Ellis, 2008) and can cause considerable damage to local apiculture (Neumann and Elzen, 2004). A range of other beetles may, however, be harmless associates of honey bee colonies (Neumann and Ritter, 2004; Ellis et al., 2008), creating a need for distinguishing between harmful and harmless beetle associates. Here we report for the first time the association of Cryptophagus hexagonalis Tournier, 1869 (Coleoptera: Cryptophagidae) with honey bee colonies. In an apiary at Baqa', Jordan, adult beetles were first found in March 2005 on the bottom boards of two A. m. ligustica colonies. The beetles were identified as Cryptophagus hexagonalis based on definitive morphological characteristics (Bruce, 1936; Fig. 1). A member of the silken fungus beetle family Cryptophagidae, both adults and larvae appear to feed exclusively on fungi and are often found on moulds associated with damp plaster, in decaying or dried plant material and on shed fur or feathers (Watson and Dallwitz, 2003). Cryptophagus hexagonalis has been described from Europe, parts of Asia, and North America where is has probably been introduced (Johnson et al., 2007). In order to clarify whether this beetle species is widespread and may cause damage, a survey was initiated of all colonies (N = 90) at seven apiaries within a distance of 3 km. All hives were investigated by pulling out each frame and carefully examining the bottom boards and hive walls. Although the A. m. ligustica (N = 64) and A. m. syriaca colonies (N = 26) were of similar size (5-10 frames of bees and 3-5 frames of brood each), adult C. hexagonalis (N = 89) where only found in 11 A. m. ligustica colonies (mean = 8.09 ± 6.44, range: 1-24). All the adult beetles were found in corners of the bottom boards, where A. tumida also hides (Neumann and Elzen, 2004). Larvae of C. hexagonalis (N = 11; identified by morphometrics, see above) were found only in the debris of six colonies which also contained adult beetles. The remaining five colonies with adult C. hexagonalis showed neither debris nor any beetle larvae, suggesting that debris may be important as an environment in which fungi find good conditions for development. No eggs were found in the debris of any colony. Likewise, no infected colonies showed any signs of comb damage or fermented honey as is caused by mass reproduction of A. tumida (Neumann and Elzen, 2004). Cryptophagus hexagonalis reproduction in the debris of honey bee colonies thus appears to be similar to the cryptic low level reproduction of A. tumida (Spiewok and Neumann, 2006). In May Fig 1. Adult of C. hexagonalis.
Thermoregulation is crucial for honey bee, Apis mellifera, colony survival in temperate regions, but possible interference by parasites is currently unknown. The small hive beetle, Aethina tumida, and the ectoparasitic mite, Varroa destructor, are honey bee parasites and both overwinter in host colonies. The efficiency of thermoregulation might thus be affected in infested host winter clusters, due to altered worker activity. Here we show for the first time that parasites can alter honey bee thermoregulation. Moreover, the data suggest that only combined infestations with V. destructor and A. tumida result in higher thermal maxima in the winter clusters, whereas infestations with one parasite alone had no significant effect compared to the controls. Due to the ubiquitous mite V. destructor combined infestations with parasites or combined infections with pathogens are almost inevitable. Therefore, our data indicate that an altered thermoregulation due to multiple infestations might be another widespread factor contributing to winter losses of honey bee colonies.