Spatial aggregation of phoretic mites on Bombus atratus and Bombus opifex (Hymenoptera: Apidae) in Argentina

International audienceMites have been observed on the bumblebee’s body and inside their nest for over 150 years, and parasitic relationships between them have occasionally been reported. One of the most interesting animal associations between mites and bees is phoresy. At present, no study has evaluated the distribution patterns of phoretic mites on bumblebees nor the factors that might be influencing such association. The main goal of this research was to determine whether an aggregation of external mites on bumblebees is influenced by (a) the phoretic mite load per bee, (b) the host species, (c) the caste of bumblebee, (d) the interaction between mite load and bee species, and (e) the presence of a suitable physical place for the mites to accommodate on the bee body. The following mite species were recorded on Bombus atratus and Bombus opifex: Kuzinia laevis, Kuzinia americana, Kuzinia affinis, Kuzinia sp., Pneumolaelaps longanalis, Pneumolaelaps longipilus, Scutacarus acarorum, and Tyrophagus putrescentiae. Our results indicate that Kuzinia mites have a strong preference for a particular region on the propodeum, which has shorter hairs than on most areas of the body. In addition, generalized linear model analysis demonstrated that mite aggregation was influenced by the caste and host species

Apis mellifera hemocytes generate increased amounts of nitric oxide in response to wounding/encapsulation

International audienceApis mellifera populations are being threatened by several pathogens and parasitosis. Several authors have proposed that honey bee colonies may suffer from a compromised immune system leading to colony loss. This is why the study of A. mellifera immune system has become a topic of pressing concern. Nitric oxide (NO) is a signaling and immune effector molecule that has been proposed as a key molecule in invertebrate immunity, and that plays a part in A. mellifera cellular defenses. This paper deals with NO participation in the response to wounding/encapsulation challenge in A. mellifera fifth instar (L5) larvae. Challenging A. mellifera L5 larvae with nylon implants enhanced NO production and spreading in granulocyte-like hemocytes and increased the number of this NO-producing hemocyte type. However, AmNOS expression levels were not influenced by the insult. These results reveal that NO participates in the wound healing/encapsulation response as a signal molecule, possibly by the activation of a constitutively expressed AmNOS in honey bees

Comparison of qPCR and Morphological Methods For Detection of Acarapis Woodi in Honey Bee Samples

The honey bee tracheal mite Acarapis woodi is an internal obligate parasite of adult honey bees (Apis mellifera). The small size of the mites and location within the bee’s trachea create a challenge for diagnostic identification. Detailed assessment of low-level mite infestation involves microscopic examination of the bee’s tracheae, but this traditional diagnostic method takes a long time. In recent years, new molecular diagnostic techniques have been developed to identify A. woodi with the use of PCRs. The purpose of this study was to compare the diagnostic sensitivity of microscopic examination and qPCR method for the detection of A. woodi in honey bee samples. Thirty-six samples were analyzed with both methods and qPCR was more sensitive than the microscopic method to detect A. woodi. This work demonstrates the practical application of molecular technology as a support tool for surveys and contingency management and to provide robust surveillance data on the presence or absence of A. woodi in honey bee colonies

Brood cell size of Apis mellifera modifies the reproductive behavior of Varroa destructor

We undertook a field study to determine whether comb cell size affects the reproductive behavior of Varroa destructor under natural conditions. We examined the effect of brood cell width on the reproductive behavior of V. destructor in honey bee colonies, under natural conditions. Drone and worker brood combs were sampled from 11 colonies of Apis mellifera. A Pearson correlation test and a Tukey test were used to determine whether mite reproduction rate varied with brood cell width. Generalized additive model analysis showed that infestation rate increased positively and linearly with the width of worker and drone cells. The reproduction rate for viable mother mites was 0.96 viable female descendants per original invading female. No significant correlation was observed between brood cell width and number of offspring of V. destructor. Infertile mother mites were more frequent in narrower brood cells.ANPCyT[07

Dietary Supplementation of Honey Bee Larvae with Arginine and Abscisic Acid Enhances Nitric Oxide and Granulocyte Immune Responses after Trauma

Many biotic and abiotic stressors impact bees' health, acting as immunosupressors and contribute to colony losses. Thus, the importance of studying the immune response of honey bees is central to develop new strategies aiming to enhance bees' fitness to confront the threats affecting them. If a pathogen breaches the physical and chemical barriers, honey bees can protect themselves from infection with cellular and humoral immune responses which represent a second line of defense. Through a series of correlative studies we have previously reported that abscisic acid (ABA) and nitric oxide (NO) share roles in the same immune defenses of Apis mellifera (A. mellifera). Here we show results supporting that the supplementation of bee larvae's diet reared in vitro with L-Arginine (precursor of NO) or ABA enhanced the immune activation of the granulocytes in response to wounding and lipopolysaccharide (LPS) injection

Interacciones parasiticas entre nosema spp y varroa destructor en Colonias de apis mellifera

The European honey bee Apis mellifera is affected by many parasites and pathogens that modify its immune system being the most destructive ectoparasitc mite Varroa destructor . The parasitic disease caused by this mite results in high mortality levels in honeybee colonies without acaricide treatment. In addition, the microsporidium Nosema apis and Nosema ceranae produce serious damages to the colonies. Taking into account that the sporulation dynamics of the microsporidium can be affected by several factors the objective of this investigation was to analyze if there are parasitic interactions between V. destructor and Nosema spp. when both parasites co-infect A. mellifera colonies. Studies were carried out in an apiary in the Entre Ríos province, Argentina. The apiary was sampled for a 10 month period. Parameters recorded per hive in fi eld examination were: (a) adult bee population (estimated as number of combs covered with adult bees); (b) brood area (estimated as number of combs covered by at least a 50 % of brood cells); (c) number of honey combs; (d) the V. destructor presence (a colony was considered parasitized by V. destructor when phoretic mite infestation was higher than 1 %) and (e) number of Nosema spp. spores (parasite abundance). Abundance of Nosema (ANij) per colony was analyzed using the mixed general additive model (GAM) with variable intercept. The fi nal data modeling confi rmed that Nosema abundance is explained by the time and by the interaction between the month and the V. destructor infestation. Possible causes explaining this ecological relationship between V. destructor and Nosema spp. populations were discussed.La abeja Europea Apis mellifera es afectada por muchos parásitos y patógenos que modifi can su sistema inmune siendo el más destructivo el ácaro ectoparasítico Varroa Destructor . La enfermedad parasitaria causada por este ácaro resulta en altos niveles de mortalidad en colonias de abejas melíferas sin tratamiento acaricida. Adicionalmente, los microsporidium Nosema apis y Nosema ceranae producen serios daños a las colonias. Tomando en consideración que la esporulación dinámica del microsporidium puede ser afectada por diversos factores, el objetivo de esta investigación fue analizar si existe interacción parasítica entre V. destructor y Nosema spp., cuando ambos parásitos co-infectan las colonias de A. mellifera. Los estudios fueron realizados en un apiario de la Provincia de Entre Ríos, Argentina. El apiario fue muestreado en un periodo de 10 meses. Durante cada revisión en campo, los siguientes parámetros por colonia fueron registrados: (a) población adulta de abejas (estimada como el número de panales cubiertos con abejas adultas); (b) área de cría (estimada como el número de panales cubiertos con al menos el 50% de celdas de cría); (c) número de panales de miel; (d) presencia de Varroa destructor (una colonia fue considerada parasitada por Varroa destructor cuando la infestación de ácaros foréticos era mayor del 1%) y el número de esporas de Nosema spp. (abundancia de parásitos). La abundancia de Nosema (ANij) por colonia fue analizada usando el Modelo estadístico Mixed General Additive model (GAM) con intercepto variable. Los datos fi nales modelados confi rmaron que la abundancia de Nosema es explicada por el tiempo y por la interacción entre el mes y la infestación de V. destructor. Posibles causas que podrían explicar esta relación ecológica entre las poblaciones de V. destructor and Nosema spp. fueron estudiadas

Antimicrobial Activity of Phenolic Extract of Apple Pomace against Paenibacillus larvae and its Toxicity on Apis mellifera

Apis mellifera populations are exposed to different biotic and abiotic stressors that affect bee survival. Paenibacillus larvae, the causative agent of American foulbrood, is one of the most important bacterial pathogens that affect bee health. In some countries, the use of antibiotics is the most common method for the prevention and treatment of P. larvae infected colonies, however this application can also increase the risk of occurrence of resistant strains. An ecological alternative is the use of vegetal extracts containing bioactive compounds, such as polyphenols. The aim of this study is to check the antimicrobial activity of phenolic extracts of apple pomace, from the cider industry, against P. larvae strains by the broth micro dilution method. In addition, the toxicity of the phenolic extracts on A. mellifera was verified using the complete exposure method. All extracts contain from 715.31 to 11348.16 μg gal/g DW, determined by Folin-Ciocalteu show antimicrobial activity against P. larvae genotype ERIC I, ranging from 23 μg/mL to 150 μg/mL. Toxicity assays of apple pomace extracts on adult bees exhibited a maximum mortality of 18% after 48h. This promising alternative will be used in the future to evaluate its toxicity at a field level

Abscisic acid enhances the immune response in Apis mellifera and contributes to the colony fitness

International audienceAbstractThe primary food of adult honey bees (Apis mellifera) is honey prepared by bees from nectar, provided by plants in order to stimulate the bee’s pollination service. Nectar consists of carbohydrates, amino acids and water, as well as other minor compounds whose proportion varies among plant species and whose biological implications in the honey bee physiology require intense research. Several environmental stressors are causing the decline of bee colonies, and thereby, we tried to connect the nutritional quality of bee’s diet with the strength of the bee’s immune system. The phytohormone abscisic acid (ABA) is present in nectar, honey and adult honey bees. It has been demonstrated that ABA stimulates innate immune defences in animal cells. However, the influence of ABA on A. mellifera’s health and fitness is unknown. Here, we show that honey bees fed with an ABA supplement in field experiments resulted in (i) the appearance of ABA in larvae and adult bees, (ii) enhanced haemocyte response to non-self recognition, (iii) improved wound healing and granulocyte and plasmatocyte activation and (iv) maximum adult bee population after the winter and increased pesticide tolerance. The results indicate that the naturally occurring compound ABA has a positive influence in honey bee immunity. ABA emerges as a potent booster of immune defence in A. mellifera and may be useful in addressing the colony losses threatening apiculture and pollination service worldwide

Toxicidad de aceites esenciales relacionados con Varroa destructor y Apis mellifera en condiciones de laboratorio

Acaricidal effect of Tagetes minuta , Heterotheca latifolia , and Eucaliptus sp. essential oils against Varroa destructor and their toxicity for Apis mellifera L. were evaluated under laboratory conditions in two assays. In the first experiment, 10 mg of plant active principles were prepared in water solution with an emulsionant at 3, 4, and 5% concentrations. For each component and to each dose, 10 females V. destructor were pulverized in a Burgerjon tower and transferred to a Petri dish with 5 bee pupae to an incubation stove at 70% RH and 33-34°C for 3 days. Dead and alive mites were counted 12, 24, and 48 h after treatment for five replications and their controls. No significant differences were found among doses of the same component and its effectiveness varied between 63 to 84% related to the control groups. In the second assay, 100 adult bees were pulverized with 10 mg of a 5% solution of the components and placed in an incubator stove at 70% RH and 33-34°C. Four replications and a control treatment for each sample were taken simultaneously. Dead and alive bees for each replication were counted 72 h post-treatments. There were not significant differences in bee mortality among the control groups (P>0.05) and it was relatively low for all treatments except for eucalyptol in which the bee mortality percentage was higher than 58%. It was concluded that T. minuta and H. latifolia essential oils can play an important role in an integrated pest management program to control Varroosis in honey bee colonies.El efecto acaricida de los aceites esenciales de Tagetes minuta , Heterotheca latifolia y Eucaliptus sp., contra Varroa destructor y su toxicidad sobre Apis mellifera L. fue evaluado en condiciones de laboratorio en dos ensayos diferentes. Para el primer ensayo, 10 mg del principio activo de las plantas fue disuelto en agua con un emulsionante al 3, 4 y 5%. Para cada componente y cada dosis, 10 hembras de V. destructor fueron pulverizadas en una torre de Burgerjon y transferidas a una cápsula de Petri con 5 pupas de abejas. Las cápsulas se mantuvieron en una estufa a 70% HR y 33-34°C durante tres días. Los ácaros muertos y vivos fueron contados a las 12, 24 y 48 h post-tratamiento para cinco réplicas y sus respectivos controles. No hubo diferencias significativas entre las dosis del mismo componente y su efectividad varió entre 63 y 84% en relación al control. En el segundo ensayo, 100 abejas adultas fueron pulverizadas con 10 mg de una solución al 5% de los componentes y colocadas en la estufa a 70% HR y 33-34°C. Cuatro réplicas y un control de cada muestra fueron tomadas simultáneamente. Las abejas muertas y vivas de cada réplica fueron contadas 72 h post-tratamiento. No hubo diferencias significativas en la mortalidad de las abejas entre los grupos control (P>0,05) y ésta fue relativamente baja para todos los tratamientos excepto para el eucaliptol cuyo porcentaje fue mayor al 58%. Se concluye que los aceites esenciales de T. minuta y H. latifolia pueden formar parte de un programa de manejo integrado de la Varroosis