Power, Karen (2020) New advances in honeybee pathology: laboratory techniques and pathological findings. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: New advances in honeybee pathology: laboratory techniques and pathological findings
Power, Karenkaren.power@unina.it
Date: 5 October 2020
Number of Pages: 170
Institution: Università degli Studi di Napoli Federico II
Department: Medicina Veterinaria e Produzioni Animali
Dottorato: Scienze veterinarie
Ciclo di dottorato: 32
Coordinatore del Corso di dottorato:
Cringoli, Giuseppegiuseppe.cringoli@unina.it
maiolino, paolaUNSPECIFIED
Date: 5 October 2020
Number of Pages: 170
Keywords: honeybee, histopathology
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > VET/03 - Patologia generale e anatomia patologica veterinaria
Date Deposited: 08 Oct 2020 11:42
Last Modified: 28 Oct 2021 12:09
URI: http://www.fedoa.unina.it/id/eprint/13264

Collection description

During the past decades, many factors have reduced the number of honeybees, with great damage to biodiversity and to agrozootechnical economics. Honeybee pollination represents a fundamental element in the ecosystem function as it ensures the reproduction of wild plants and agricultural crops as well as genetic variability among species, thus defending global biodiversity. Moreover, honeybee products are very appreciated and nowadays they are of great interest for the therapeutic properties of their compounds. Although the synergistic action of different factors (including bacteria, virus, parasites, pesticides) has been identified as the source of loss of honeybees, very little information is available about how these factors actually affect the health of honeybees. For many years, veterinary pathologists have shown little interest in the study of honeybee pathology, and very few studies are currently available. However, the knowledge possessed by veterinary pathologists could support the studies of researchers pertaining to other fields and unravel the mysteries around colony losses. The present research collects the experiments and the results of a three year PhD program spent studying honeybee pathology. Each study proposes a new laboratory technique and describes the pathological findings connected to three pathologies, namely Deformed Wing Virus (DWV), male hypofertility and Nosemosis In Chapter 1 a study on DWV infected honeybees is presented with the aim of enriching knowledge about etiopathogenesis. Honeybee samples with and without clinical signs were collected from a DWV clinically infected hive and analysed to highlight the presence of the virus and determine the relative viral load through biomolecular techniques. Subsequently, using an innovative fixating technique, honeybee samples were subjected to anatomo-histopathological analysis. The virus was identified in all samples analysed, and the viral load was higher in symptomatic samples compared to the asymptomatic group. The anatomopathological analysis confirmed the presence of the typical signs of DWV infection: crippled wing, short and discoloured abdomens. In samples showing clinical signs, by histopathology we observed alterations of the hypopharyngeal glands and thoracic muscles, while samples with no apparent clinical signs showed the presence of inflammatory cells, as well as melanisation in the midgut and in the hemocele. The results suggest a possible pathological action of DWV in both clinical and subclinical infections. The Chapter 2 describes the methods and the results of a study on the reproductive system and spermatozoa of Apis mellifera ligustica, carried out in collaboration with the Unity of General Zootechnics and Genetic Improvement of the Department of Veterinary Medicine and Animal Productions of the University of Naples “Federico II”. The reproductive system of drones was analysed by anatomopathology and testes were examined by histopathology. No macroscopic alterations were observed in any sample and through histopathology most of the samples showed unaltered testes, although in some cases they showed degenerated seminiferous tubules, while others appeared immature. Moreover, using an innovative technique, the morphological features and morphometric parameters of spermatozoa were studied. The following morphometric values (mean ± standard deviation) were measured: sperm total length (230,81±17,22 μm), tail length (222,96±17,15μm), head length (7,85±0,65μm), nucleus length (4,44±0,61μm) and perforator length (3,58±1,21μm). Additionally, 7% of the spermatozoa showed the presence of visible defects such as double, split or broken tails. The results obtained provide data about morphology of testes and morphometry and morphology of spermatozoa of drones of A. mellifera ligustica and show the presence of alterations. In Chapter 3 two different techniques for the diagnosis of Nosemosis are presented. Samples of adult honeybees were analysed with anatomo-histopathological analysis and, for the first time, the Mini-FLOTAC technique was applied to the beekeeping field to detect Nosema spp. spores. The anatomopathological analysis did not reveal any alterations of the midgut while the histopathological analysis revealed the presence of spores in the midgut and in the Malpighian tubules, and both organs appeared strongly degenerated. The Mini-FLOTAC technique was compared with two different microscopic techniques, direct smear and microscopic examination with the use of the hemocytometer, in order to assess the possible use in honeybees. The results confirmed the validity of the three techniques to highlight the presence of the spores of Nosema. However, the Mini-FLOTAC technique proved to be more user-friendly and a better tool for spore detection, especially when the infection level is low, thanks the high sensitivity, precision and accuracy of the technique. This study was carried out in collaboration with the Unity of Parasitology and Parasitic Diseases of the Department of Veterinary Medicine and Animal Productions of the University of Naples “Federico II”. The results obtained from the different studies show the efficacy and the effectiveness of applying laboratory and diagnostic techniques already validated in other animals and humans in honeybee pathology, although by introducing some modifications due to the particular characteristics of the samples. Moreover, it appears evident that the pathologies here studied, particularly DWV and Nosemosis can impair the immune response of honeybees, corroborating the idea of a key role of immunity in the fight of honeybees against different stressors. Finally, the presence of alterations affecting the male reproductive system, suggests that honeybees have the potential of being bioindicators of the presence of endocrine disruptors in the environment that could also affect fertility in male humans.


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