Chemical Ecology and Management of the Small Hive Beetle, Aethina tumida (Coleoptera: Nitidulidae)

Cane J.H.

Among the ground-nesting bees are several proven crop pollinators, but only the alkali bee ( Nomia melanderi) has been successfully managed. In <80 years, it has become the world's most intensely studied ground-nesting solitary bee. In many ways, the bee seems paradoxical. It nests during the torrid, parched midsummer amid arid valleys and basins of the western United States, yet it wants damp soil. In these basins, extensive monocultures of an irrigated Eurasian crop plant, alfalfa (lucerne), subsidize millions of alkali bees. Elsewhere, its polylectic habits and long foraging range allow it to stray into neighboring crops contaminated with insecticides. Primary wild floral hosts are either non-native or poorly known. Kleptoparasitic bees plague most ground nesters, but not alkali bees, which do, however, host other well-studied parasitoids. Building effective nesting beds requires understanding the hydraulic conductivity of silty nesting soils and its important interplay with specific soil mineral salts. Surprisingly, some isolated populations endure inhospitably cold climates by nesting amid hot springs. Despite the peculiarities and challenges associated with its management, the alkali bee remains the second most valuable managed solitary bee for US agriculture and perhaps the world. Expected final online publication date for the Annual Review of Entomology, Volume 69 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Negi R., Sharma B., Kaur S., Kaur T., Khan S.S., Kumar S., Ramniwas S., Rustagi S., Singh S., Rai A.K., Kour D., Thakur N., Yadav A.N.

AbstractAgriculture is the backbone of developing countries, which plays an essential role in primary drivers of economy. The increasing use of chemical fertilizers and toxic insecticides endangers the health of human, plant soils, and the environment. Microbial insecticides have been implemented in current scenario for crop protection. Biological agents for pest control have gained more attention in recent year as substitutes for management of pests and pathogens. It provides a sustainable approach to plant health management and assists to minimize the excessive applications of toxic substances. The antagonistic microbes belong to six different phyla including Bacillota, Actinomycetota, Pseudomonadota, Bacteroidota and Mucoromycota. Microbial pesticides have been developed through a number of processes, including extraction of pure culture and screening using effectiveness bioassays under controlled and natural conditions. Biological control agents (BCAs) are recognized to be the most sophisticated technology for environmentally friendly agriculture. The various beneficial BCAs have been reported for the management of plant health, but they required effective acceptance together with the standardization of bioformulation. The present review deals with the recent development of microbial control agents, mechanisms of actions, development of microbial pesticides and their potential applications for agricultural productivity.

Abd El-Ghany N.M.

Liu J., Chen M., Ma W., Zheng L., Zhang B., Zhao H., Jiang Y.

Strawberries are popular fruits around the world, and their yield and fruit quality rely on pollination by honey bees and bumblebee colonies. Both bee species have their own advantages in strawberry pollination. This study investigates the characteristic of strawberry (Fragaria × ananassa ‘Red Face’) flower volatiles and their effects on bee pollinators by (1) detecting the volatile compounds of strawberry flowers by polydimethylsiloxane (PDMS) combined gas chromatography-mass spectrometry (GC-MS), (2) determining whether Bombus terrestris or Apis mellifera showed antennae responses to certain compounds of strawberry flower volatiles by an electroantennography test (EAG), and (3) testing whether these compounds could elicit a corresponding behavioral response in bees. The results showed that (1) there were 38 chemical compounds in ‘Red Face’ volatiles with 7 types, most of which were known to be generally emitted by flowers but also have some compounds that have not been reported in strawberry flowers; (2) B. terrestris and A. mellifera had strong EAG responses to several compounds, respectively, especially to ethyl benzoate, (Z)-3-hexenyl propionate, (Z)-3-hexenyl acetate, benzeneacetaldehyde and melonal; and (3) both bee species showed significant avoidance behaviors to four tested compounds, especially the B. terrestris. Flower volatiles of strawberry ‘Red face’ were different from other strawberry varieties that have been reported; some of these electrophysiologically active compounds could cause antennal potential responses in bees, as well as behavioral responses. Our study supports the idea that strawberry flower volatiles are one of the factors influencing bee foraging decisions and provides a reference for formulating more reasonable bee pollination to improve strawberry fruit quality.

Roubik D.W.

Stingless bees form perennial colonies of honey-making insects. The >600 species of stingless bees, mainly Neotropical, live throughout tropical latitudes. Foragers influence floral biology, plant reproduction, microbe dispersal, and diverse ecosystem functions. As tropical forest residents since the upper Cretaceous, they have had a long evolutionary history without competition from honey bees. Most stingless bees are smaller than any Apis species and recruit nest mates to resources, while their defense strategies exclude stinging behavior but incorporate biting. Stingless bees have diversified ecologically; excel in nesting site selection and mutualisms with plants, arthropods, and microbes; and display opportunism, including co-opting plant defenses. As their biology becomes better known, applications to human endeavors are imposing selective pressures from exploitation and approaches to conservation that entail colony extraction from wildlands. Although some meliponines can adjust to new conditions, their populations shall require tropical diversity for survival and reproduction. Expected final online publication date for the Annual Review of Entomology, Volume 68 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Chen X., Chen R., He D., Huang M.

Abstract The small hive beetle (SHB), as one of the six major pathogens of honeybee, has invaded China in recent years and caused serious harm to the apiculture industry of China. In order to explore the feeding mechanism of Aethina tumida, we used scanning electron microscopy for the first time to conduct a detailed study on the morphology and structure of antennae and mouthparts, including the distribution and abundance of sensilla. The results showed that its clavate antennae and chewing mouthparts are similar to those of other nitidulid on the structure and types of sensilla. There are 5 types of sensilla were identified on antennae: 3 subtypes of sensilla chaetica (SC), 1 type of sensilla trichodea (SP), 6 subtypes of sensilla basiconica (SB), 2 subtypes of sensilla styloconica (SS) and 1 type of Böhm bristles (BB); 8 types of sensilla on mourthparts: 1 type of SC, 8 subtypes of SB, 2 subtypes of SP, 2 subtypes of SS, 1 type of SM, 1 type of sensilla coelocinica (Sco), 2 subtypes of campaniformia (Scam) and 1 type of BB. We also compared the differences of sensilla with the only reported nitiduline species Omosita colon and inferred their sensory function.

Zhao R., Wang H., Gao J., Zhang Y., Li X., Zhou J., Liang P., Gao X., Gu S.

Recent studies have indicated that the plant volatile methyl benzoate (MB) exhibits significant insecticidal bioactivity against several common insects. However, the potential environmental hazards of MB and its safety to non-target organisms is poorly understood. In the present study, these characteristics were investigated through laboratory experiments and field investigations. The results revealed that MB was highly toxic to the agricultural pest, fall armyworm Spodoptera frugiperda. Compared with the commercial pesticide lambda-cyhalothrin, the toxicities of MB against S. frugiperda larvae and adults were comparable and 3.41 times higher, respectively. Behavioral bioassays showed that the percentage repellency of MB to S. frugiperda larvae was 56.72 %, and MB induced 69.40 % oviposition deterrence rate in S. frugiperda female adults. Furthermore, in terms of median lethal concentration (LC50) and median lethal doses (LD50), MB exhibited non-toxic effects on non-target animals with 3-d LC50 of > 1 % to natural predators (Coccinella septempunctata and Harmonia axyridis), 3-d LD50 of 467.86 µg/bee to the bumblebee Bombus terrestris, 14-d LC50 of 971.09 mg/kg to the earthworm Eisenia fetida, and 4-d LC50 of 47.30 mg/L to the zebrafish Brachydanio rerio. The accumulation of MB in the soil and earthworms was found to be extremely limited. Our comparative study clearly demonstrated that MB is effective as a selective botanical pesticide against S. frugiperda and it is safe to use in the tested environment, with no toxic effects on non-target animals and natural predators.

NTALLI N.G., SPOCHACZ M., ADAMSKI Z.

Among pests of bees and beehives, arthropods make up a large and important group. Mites like Varroa destructor, Acarapis woodi, or Tropilaelaps spp., beetles (Aethina tumida, Oplostomus spp.), and lepidopterans (Galleria mellonella, Achroia grisella) decrease honey bee population and vitality, with subsequent significant colony production losses. Synthetic chemicals have been traditionally used to protect honey bee colonies from pests’ infestations but they have often been of poor selectivity, consequent high toxicity to bees and humans, and resistance development by the targeted apiary pests. The current European policy encourages the usage of eco-friendly methods to combat bee pests and the international research highlights plant secondary metabolites as candidate alternatives of significance. In this review, we argue the potential of plant-derived substances in the protection of the bee colonies against their arthropod pests. The before mentioned major apiary arthropods are briefly described followed by the recent reports on the botanical extracts and notable constituent compounds exhibiting activity against them. We discuss the different ways the essential oils are reported to be applied to the bee or the apiary, along with the importance of the application method to the exhibited efficacy. We designate synergism issues of blends, attractants, and repellency cases, as well as selectivity and mode of action as reported for bees or insect pests.

AMOS B.A., FURLONG M.J., LEEMON D.M., CRIBB B.W., HAYES R.A.

The small hive beetle, Aethina tumida (Coleoptera: Nitidulidae), is an economically important pest of the Western honeybee, Apis mellifera (Hymenoptera: Apidae). We investigated the effect of rearing environment on the cuticular chemical profile of adult A. tumida, using hexane to extract the hydrocarbons and other compounds from the cuticles of beetles. Beetles were collected from A. mellifera colonies in Australia as well as reared in single sex laboratory cultures on different diets. We investigated whether rearing environment (laboratory vs. field, different apiaries, access to mating partners, diet) had any effect on cuticular hydrocarbons. Coupled gas chromatography–mass spectrometry analyses of the extracts showed that rearing environment had significant qualitative and quantitative effects on the hydrocarbons detected. The data support the hypothesis that cuticular profiles of A. tumida are contingent on environment, partitioning on the basis of rearing diet and source hives. The finding has implications for the regulation of interactions between A. tumida and honeybees and improvements in targeting of management strategies.

Sabella G., Mulè R., Robba L., Agrò A., Manachini B.

Abstract The European bee, Apis mellifera L. (Hymenoptera: Apidae), is a fundamental resource for the pollination of a great variety of botanical species used by humans for sustenance. Over the last few decades, bee colonies have become vulnerable to a new pest that has advanced beyond its native sub-Saharan territory: the small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae). This currently presents a pressing problem in the United States and Australia, but it has also been recorded in Portugal and Italy and it is likely to spread in the rest of Europe too. This study represents a systematic review, based on EFSA guidelines, of the various control treatments for small hive beetles in order to identify the most effective methods as well as, those with no effects on bee colonies. The results show that the bulk of these studies were performed in the United States and that a number of treatments are suitable for the control of A. tumida, though some have negative effects on bees while others have low effectiveness or are ineffective. The best results are those with the entomopathogenic nematodes of the genus Steinernema and Heterorhabditis, but also with formic acid or diatomaceous earth. Various products containing insecticides have been effective, for example, Perizin (Bayer), GardStar (Y-Tex), CheckMite+ strips (Bayer), but Apithor (Apithor ) cannot be used in Europe because it contains Fipronil, which has been banned since 2013. Some common products like bleach and detergent have also been effective.

Papach A., Balusu R., Williams G.R., Fadamiro H.Y., Neumann P.

Roth M.A., Wilson J.M., Gross A.D.

Abstract Small hive beetle (Aethina tumida Murray) control has become an issue of increasing importance for North American apiculturists throughout the past two decades. Aethina tumida was discovered in Florida in 1989, presumably transported from its native habitat of sub-Saharan Africa through the shipment of European honey bee (Apis mellifera L) queens. Estimates of damage from A. tumida were as high as $3 million annually in the United States by the year 2004, and A. tumida was found in nearly every state by 2008. When adult beetles emerge from pupation in soil surrounding the hive, they are attracted to A. mellifera hives through a variety of pheromones and volatile organic compounds from bees and hive products. Aethina tumida larvae and adults consume hive products and bee brood, generating fermenting waste (or slime), which can eventually lead to hive abandonment in cases of severe infestation. Pest management efforts for A. tumida have focused on trapping adults, applying lime, diatomaceous earth, pyrethroid soil drenches, and entomopathogenic nematodes to the soil surrounding A. mellifera hives. Understanding the biology and life history of A. tumida, along with current control methods, can aid apiculturists in making informed integrated pest management decisions. Additionally, understanding critical knowledge gaps in the current research is an important step in identifying promising future management tactics in the ongoing efforts to manage this invasive pest.

Cornelissen B.(., Neumann P.

Stuhl C.J.

Papach A., Cappa F., Cervo R., Dapporto L., Balusu R., Williams G.R., Neumann P.

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.