Expression of the Prophenoloxidase Gene and Phenoloxidase Activity, During the Development of Apis Mellifera Brood Infected with Varroa Destructor

AbstractThe pathogenesis of varroasis has not been fully explained despite intensive research. Earlier studies suggested that parasitic infections caused by Varroa destructor mites were accompanied by immunosuppression in the host organism. The objective of this study was to analyse the influence of varroasis on one of the immune pathway in Apis mellifera measured by the expression of the prophenoloxidase (proPO) gene and the enzymatic activity of this gene’s product, phenoloxidase (EC 1.14.18.1). An evaluation was done of five developmental stages of honey bee workers and drones. The relative expression of proPO decreased in infected individuals. The only exceptions were worker prepupae (PP) and drone pupae with brown eyes and dark brown thorax (P5) where propo gene expression was 1.8-fold and 1.5-fold higher, respectively, than in the control. Phenoloxidase (PO) activity was 2.8-fold higher in infected pp workers and 2-fold higher in p5 drones in comparison with uninfected bees. Phenoloxidase activity was reduced in the remaining developmental stages of infected workers and drones. The relative expression of proPO was positively correlated with the relative PO activity in both workers (r = 0.988) and drones (r = 0.996). The results of the study indicate that V. destructor significantly influences the phenoloxidase-dependent immune pathway in honey bees.

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Expression and Activity of Lysozyme in Apis Mellifera Carnica Brood Infested with Varroa Destructor

Journal of Apicultural Science ◽

10.1515/jas-2017-0014 ◽

2017 ◽

Vol 61 (2) ◽

pp. 253-256 ◽

Cited By ~ 1

Author(s):

Ewa A. Zaobidna ◽

Krystyna Żółtowska ◽

Elżbieta Łopieńska-Biernat

Keyword(s):

Gene Expression ◽

Apis Mellifera ◽

Honey Bee ◽

Varroa Destructor ◽

Developmental Stages ◽

Lysozyme Activity ◽

Apis Mellifera Carnica ◽

Relative Expression ◽

Stage Of Development ◽

And Gender

Abstract Varroa destructor is a parasitic mite that attacks the honey bee, and previous studies have suggested that parasitosis caused by this mite is accompanied by immunosuppresion in the host. In this study, the effect of mite infestation on the expression of the lysozyme-1 (lys-1) gene and lysozyme activity in Apis mellifera carnica was determined. The experiment was carried out on the five developmental stages of honey bee workers and drones. Developmental and gender-related differences in gene expression and lysozyme activity were observed in a Varroa destructor-infested brood. The relative expression of the lys-1 gene increased in a infested worker brood and decreased in a drone brood except for P3 pupae. In the final stage of development, the lys-1 gene expression was significantly lower in infested newly emerged workers and drones. Changes in the relative expression of the lys-1 gene in infested individuals was poorly manifested at the level of enzyme activity, whereas at the two final stages of development (P5 and I) there was a positive correlation between relative lys-1 expression and lysozyme activity in infested bees of both genders (r=0.988, r=0.999, respectively). The results of this study indicate that V. destructor influences the lysozyme-linked immune response in bees.

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Exploring Two Honey Bee Traits for Improving Resistance Against Varroa destructor: Development and Genetic Evaluation

Insects ◽

10.3390/insects12030216 ◽

2021 ◽

Vol 12 (3) ◽

pp. 216

Author(s):

Matthieu Guichard ◽

Benoît Droz ◽

Evert W. Brascamp ◽

Adrien von Virag ◽

Markus Neuditschko ◽

...

Keyword(s):

Apis Mellifera ◽

Honey Bee ◽

Honey Bees ◽

Varroa Destructor ◽

Field Trial ◽

Genetic Evaluation ◽

Phenotypic Correlation ◽

Apis Mellifera Mellifera ◽

Novel Traits ◽

Resistance Traits

For the development of novel selection traits in honey bees, applicability under field conditions is crucial. We thus evaluated two novel traits intended to provide resistance against the ectoparasitic mite Varroa destructor and to allow for their straightforward implementation in honey bee selection. These traits are new field estimates of already-described colony traits: brood recapping rate (‘Recapping’) and solidness (‘Solidness’). ‘Recapping’ refers to a specific worker characteristic wherein they reseal a capped and partly opened cell containing a pupa, whilst ‘Solidness’ assesses the percentage of capped brood in a predefined area. According to the literature and beekeepers’ experiences, a higher recapping rate and higher solidness could be related to resistance to V. destructor. During a four-year field trial in Switzerland, the two resistance traits were assessed in a total of 121 colonies of Apis mellifera mellifera. We estimated the repeatability and the heritability of the two traits and determined their phenotypic correlations with commonly applied selection traits, including other putative resistance traits. Both traits showed low repeatability between different measurements within each year. ‘Recapping’ had a low heritability (h2 = 0.04 to 0.05, depending on the selected model) and a negative phenotypic correlation to non-removal of pin-killed brood (r = −0.23). The heritability of ‘Solidness’ was moderate (h2 = 0.24 to 0.25) and did not significantly correlate with resistance traits. The two traits did not show an association with V. destructor infestation levels. Further research is needed to confirm the results, as only a small number of colonies was evaluated.

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Evaluating the Efficacy of 30 Different Essential Oils against Varroa destructor and Honey Bee Workers (Apis mellifera)

Insects ◽

10.3390/insects12111045 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1045

Author(s):

Marian Hýbl ◽

Andrea Bohatá ◽

Iva Rádsetoulalová ◽

Marek Kopecký ◽

Irena Hoštičková ◽

...

Keyword(s):

Essential Oils ◽

Honey Bees ◽

Varroa Destructor ◽

Mortality Rates ◽

Selectivity Ratio ◽

Varroa Mites ◽

Main Components ◽

Honey Bee Workers ◽

Over Time ◽

Better Than

Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as well as the effect against honey bees, is not known. In this study, 30 different essential oils were screened by using a glass-vial residual bioassay. Essential oils showing varroacidal efficacy > 70% were tested by the complete exposure assay. A total of five bees and five mites were placed in the Petri dishes in five replications for each concentration of essential oil. Mite and bee mortality rates were assessed after 4, 24, 48, and 72 h. The LC50 values and selectivity ratio (SR) were calculated. For essential oils with the best selectivity ratio, their main components were detected and quantified by GC-MS/MS. The results suggest that the most suitable oils are peppermint and manuka (SR > 9), followed by oregano, litsea (SR > 5), carrot, and cinnamon (SR > 4). Additionally, these oils showed a trend of the increased value of selective ratio over time. All these oils seem to be better than thymol (SR < 3.2), which is commonly used in beekeeping practice. However, the possible use of these essential oils has yet to be verified in beekeeping practice.

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Factors restraining the population growth of Varroa destructor in Ethiopian honey bees (Apis mellifera simensis)

PLoS ONE ◽

10.1371/journal.pone.0223236 ◽

2019 ◽

Vol 14 (9) ◽

pp. e0223236 ◽

Cited By ~ 5

Author(s):

Haftom Gebremedhn ◽

Bezabeh Amssalu ◽

Lina De Smet ◽

Dirk C. de Graaf

Keyword(s):

Apis Mellifera ◽

Population Growth ◽

Honey Bees ◽

Varroa Destructor

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Deformed Wing Virus Infection in Honey Bees (Apis mellifera L.)

Veterinary Pathology ◽

10.1177/0300985819834617 ◽

2019 ◽

Vol 56 (4) ◽

pp. 636-641 ◽

Cited By ~ 5

Author(s):

Roman V. Koziy ◽

Sarah C. Wood ◽

Ivanna V. Kozii ◽

Claire Janse van Rensburg ◽

Igor Moshynskyy ◽

...

Keyword(s):

Apis Mellifera ◽

Honey Bee ◽

Honey Bees ◽

Rna Virus ◽

Mandibular Glands ◽

Deformed Wing Virus ◽

Clinically Normal ◽

Bee Health ◽

Honey Bee Health ◽

Honey Bee Workers

Deformed wing virus (DWV) is a single-stranded RNA virus of honey bees ( Apis mellifera L.) transmitted by the parasitic mite Varroa destructor. Although DWV represents a major threat to honey bee health worldwide, the pathological basis of DWV infection is not well documented. The objective of this study was to investigate clinicopathological and histological aspects of natural DWV infection in honey bee workers. Emergence of worker honey bees was observed in 5 colonies that were clinically affected with DWV and the newly emerged bees were collected for histopathology. DWV-affected bees were 2 times slower to emerge and had 30% higher mortality compared to clinically normal bees. Hypopharyngeal glands in bees with DWV were hypoplastic, with fewer intracytoplasmic secretory vesicles; cells affected by apoptosis were observed more frequently. Mandibular glands were hypoplastic and were lined by cuboidal epithelium in severely affected bees compared to tall columnar epithelium in nonaffected bees. The DWV load was on average 1.7 × 106 times higher ( P < .001) in the severely affected workers compared to aged-matched sister honey bee workers that were not affected by deformed wing disease based on gross examination. Thus, DWV infection is associated with prolonged emergence, increased mortality during emergence, and hypoplasia of hypopharyngeal and mandibular glands in newly emerged worker honey bees in addition to previously reported deformed wing abnormalities.

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