**About the Editors**

**Giovanni Cilia** graduated *cum laude* with a Veterinary Biotechnological Sciences master's degree in 2016 at the University of Milan (Italy). He obtained a Ph.D. in Veterinary Sciences from the Department of Veterinary Sciences at the University of Pisa. Since 2021, he has been working at CREA Research Centre for Agriculture and Environment in Bologna, working on honey bee pathogens and molecular biology. He performs support teaching and seminar activities for the courses of "Infectious Bacterial Diseases", "Microbiology and Immunology", "Microbiology and Biotechnology Applied to Animal Production", and "Veterinary Hygiene" in the Department of Veterinary Sciences at the University of Pisa. During his activities, he applied for an internship at a different research institute, including the Biology of Spirochetes Unit, National Reference Center for Leptospirosis of Institute Pasteur (Paris, France). His research was focused on bacterial infectious diseases in domestic animals and wildlife. At present, his research topics include antibacterial activity of natural substances and infectious diseases in honey bee and insect molecular biology, with particular attention given to honey bee virus, nosemosis, and pests. He is the author/co-author of several scientific publications in international journals, the Editor of some infectious disease Special Issues, and the Topic Editor of "Veterinary Sciences".

**Antonio Nanetti** graduated *cum laude* with a degree in Science of Animal Production from the University of Bologna, Italy, in 1992. In 1979, he began working at the former National Institute of Beekeeping, the reference Italian Institution in apicultural research, which was recently incorporated into the Research Centre for Agriculture and Environment of the Italian Council for Agricultural Research and Economics (CREA). Within this institution, he is a researcher belonging to the apidological team, where he runs research projects focused on honey bees. His research covers the main honey bee pests and diseases, with a particular focus on exotic parasites and pathogens, such *as Varroa destructor, Nosema ceranae*, and *Aethina tumida*. His research activities have enabled considerable progress to be made in the control of bee diseases with natural compounds. He has also contributed to the ground-breaking research fields of honey bee welfare and the impact of climate change on pollinators. He has authored/co-authored more than 170 publications of different kinds, is the co-editor of a book on the welfare of managed honey bees, which is presently in preparation, and acted as a guest editor for a Special Issue on 'Honey Bee Health' in the journal Veterinary Science.

### *Editorial* **Honey Bee Health**

**Giovanni Cilia \* and Antonio Nanetti**

CREA Research Centre for Agriculture and Environment (CREA-AA), Via di Saliceto 80, 40128 Bologna, Italy; antonio.nanetti@crea.gov.it

**\*** Correspondence: giovanni.cilia@crea.gov.it; Tel.: +39-051-353103

Honey bee health is a crucial issue that has recently received increased interest from researchers, stakeholders, and citizens.

To explore all possible features of honey bee health, this Special Issue, "Honey Bee health", aims to explore this topic through a series of research articles focused on different aspects of honey bee health at different levels, including molecular health, microbial health, and population genetic health. All the 21 published articles explore this theme and emphasize the importance of this issue.

Factors associates with honey bee colony losses were reviewed by Hristov et al. [1], and Amiri et al. analysed the interest in honey bee research [2]. Donkersley et al. report a One Health model to reverse honey bee decline [3].

Ribani et al. used environmental DNA (eDNA) to monitor honey bee pathogens and parasites, demonstrating that *V. destructor* is widespread and *L. passim* and *A. apis* with *N. ceranae* occurr frequently together [4].

*V. destructor* infections were modelled, suggesting that colony survival is sensitive to the hive grooming rate and reproductive rate of the mites, which is enhanced in dronecapped cells [5], whereas a new sampling and treatment of this pathogen was found to be a favourable and sustainable method of management [6].

Mendoza et al. found that *V. destructor* resistant honey bees have greater behavioural resistance than susceptible honey bees. At the end of the summer, resistant honey bees had fewer mites and a lower deformed wing virus type A (DWV-A) viral load than susceptible honey bees. Additionally, resistant honey bees were *A. mellifera scutellata* hybrids, whereas susceptible ones were closer to European subspecies [7].

The most promising molecular genetic markers for determining resistance to nosemosis in dark forest bees are microsatellite loci *AC117*, *Ap243,* and *SV185*, which were investigated by Ostroverkhova [8].

Emsen et al. evaluated the seasonality of *N. ceranae* and their relationship with honey bee survivorship, highlighting the highest infection rates, prevalence, and spore viability in the spring and summer, associated with reduced bee populations and food stores in colonies [9].

In the honey bee population in Asia, *Nosema* infection was found in 65% of apiaries by Ostroverkhova et al. Both *N. apis* and *N. ceranae* occur across subarctic and warm summer continental climates, but *N. ceranae* is more predominant in the latter, even if coinfections are predominant (36.3%) [10]. The presence of *N. apis* was also investigated by Naudi et al. in Estonia and Latvia. The results show that *N. apis* is dominant in Estonia (43%) and *N. ceranae* in Latvia (47%) [11].

Porrini et al. studied the effect of compounds commonly used to treat varroosis, evaluating the CHC profiles and EO production on *N. ceranae* infected and non-infected honey bees. The results indicate an absence of alteration in EO or CHC as a response to acaricides ingestion, suggesting that worker honey bees exposed to these highly ubiquitous drugs are hardly differentiated by nest-mates [12].

The efficacy of ApiHerb® and Api-Bioxal® as treatments against *N. ceranae* were investigated using two qPCR methods based on the *16S rRNA* and *Hsp70* genes. Both

**Citation:** Cilia, G.; Nanetti, A. Honey Bee Health. *Vet. Sci.* **2021**, *8*, 127. https://doi.org/10.3390/vetsci8070127

Received: 9 April 2021 Accepted: 26 June 2021 Published: 6 July 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

treatments reduced the abundance of *N. ceranae*, but ApiHerb also decreased the prevalence of infected bees. From the analysis, the qPCR method based on the *Hsp70* gene ensures a higher accuracy for the exact quantification of *N. ceranae* [13].

Dittes et al. discussed the veterinary approach to adult bee examination by analysing the differential diagnosis of the common virus diseases: Acute Bee Paralysis Virus (ABPV)- Kashmir Bee Virus (KBV)-Israeli Acute Paralysis Virus (IAPV)-Complex, Chronic Bee Paralysis Virus (CBPV), and DWV, as well as coinfections such as *Varroa* spp. and *Nosema* spp. [14].

The DWV-A transmission via hive products was investigated in a fully-crossed hoarding cage experiment, estimating the transmission risk by screening commercial products. The results show that DWV-A transmission via hive products is feasible, but the risk of introducing novel viruses and/or strains should be considered [15].

A case report highlights treatment and sanitary measures to save two *A. mellifera carnica* CBPV-infected colonies before the winter [16].

Bullock et al. proposed a silicone wristband as passive samplers in a beehive, developing a novel approach to passively sample honey bee hives. The silicone wristbands provide a simple, affordable, and passive method for sampling the chemical environment of honey bees [17].

Ludvigsen et al. evaluated the honey bee gut mycobiota cluster in different seasons and gut segments. The main finding was that bacteria cluster by gut segments, while fungi cluster by season [18]. Additionally, the administration of veterinary drugs, dietary supplements, and non-protein amino acids affected the ventriculum microbiological profile of *A. mellifera ligustica* [19].

Terenzi et al. reviewed the importance of the sound emitted by the hive. It is used by the bees to communicate within the hive, and its analysis can reveal useful information to understand the colony health status and to detect colony variations [20].

Power et al. found an innovative histological processing technique to analyse healthy drones of *A. mellifera ligustica.* The new approach can detect testes alterations, such as degenerated seminiferous tubules [21].

**Author Contributions:** G.C. and A.N. conceptualized, wrote, and reviewed the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Acknowledgments:** We are grateful to all authors and reviewers who participated in this Special Issue.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

