The Fungus Nosema ceranae and a Sublethal Dose of the Neonicotinoid Insecticide Thiamethoxam Differentially Affected the Health and Immunity of Africanized Honey Bees.

Honey bees (Apis mellifera L.) are affected by different biotic and abiotic stressors, such as the fungus Nosema ceranae and neonicotinoid insecticides, that negatively impact their health. However, most studies so far conducted have focused on the effect of these stressors separately and in European honey bees. Therefore, this study was conducted to analyze the impact of both stressors, singly and in combination, on honey bees of African descent that have demonstrated resistance to parasites and pesticides. Africanized honey bees (AHBs, Apis mellifera scutellata Lepeletier) were inoculated with N. ceranae (1 × 105 spores/bee) and/or chronically exposed for 18 days to a sublethal dose of thiamethoxam (0.025 ng/bee) to evaluate their single and combined effects on food consumption, survivorship, N. ceranae infection, and immunity at the cellular and humoral levels. No significant effects by any of the stressors were found for food consumption. However, thiamethoxam was the main stressor associated to a significant decrease in AHB survivorship, whereas N. ceranae was the main stressor affecting their humoral immune response by upregulating the expression of the gene AmHym-1. Additionally, both stressors, separately and combined, significantly decreased the concentration of haemocytes in the haemolymph of the bees. These findings indicate that N. ceranae and thiamethoxam differentially affect the lifespan and immunity of AHBs and do not seem to have synergistic effects when AHBs are simultaneously exposed to both stressors.

Nosema ceranae causes cellular immunosuppression and interacts with thiamethoxam to increase mortality in the stingless bee Melipona colimana.

The microsporidian parasite Nosema ceranae and neonicotinoid insecticides affect the health of honey bees (Apis mellifera). However, there is limited information about the effect of these stressors on other pollinators such as stingless bees (Hymenoptera: Meliponini). We examined the separate and combined effects of N. ceranae and the neonicotinoid thiamethoxam at field-exposure levels on the survivorship and cellular immunity (hemocyte concentration) of the stingless bee Melipona colimana. Newly-emerged bees were subjected to four treatments provided in sucrose syrup: N. ceranae spores, thiamethoxam, thiamethoxam and N. ceranae, and control (bees receiving only syrup). N. ceranae developed infections of > 467,000 spores/bee in the group treated with spores only. However, in the bees subjected to both stressors, infections were < 143,000 spores/bee, likely due to an inhibitory effect of thiamethoxam on the microsporidium. N. ceranae infections did not affect bee survivorship, but thiamethoxam plus N. ceranae significantly increased mortality. Hemocyte counts were significantly lower in N. ceranae infected-bees than in the other treatments. These results suggest that N. ceranae may infect, proliferate and cause cellular immunosuppression in stingless bees, that exposure to sublethal thiamethoxam concentrations is toxic to M. colimana when infected with N. ceranae, and that thiamethoxam restrains N. ceranae proliferation. These findings have implications on pollinators' conservation.

Evidence of presence and replication of honey bee viruses among wild bee pollinators in subtropical environments.

We determined the presence of six viruses in different bee species collected in subtropical environments. Deformed wing virus (DWV) and black queen cell virus (BQCV) were detected in >90% of honey bee samples and in 50-100% of four stingless bee, two bumble bee and one solitary bee species. Additionally, minus DWV and BQCV RNA strands were detected, indicating that the viruses replicate in several hosts. This is the first report of honey bee viruses replicating in six wild bee species in the tropics. If pathogenic to them, viral infections could result in negative impacts in agricultural and unmanaged ecosystems.

Polimorfismo rs4285184 del gen MGAT1 como factor de riesgo de obesidad en la población mexicana / The rs4285184 polymorphism of the MGAT1 gene as a risk factor for obesity in the Mexican population

Antecedentes y objetivo: La obesidad es un factor que contribuye a la morbilidad de ciertas enfermedades, y a la mortalidad mundial. MGAT1 es una glucosiltransferasa implicada en la síntesis de los oligosacáridos ligados a proteínas y lípidos, y es posible que sus polimorfismos estén implicados en la etiología de la obesidad. Investigamos la asociación entre el polimorfismo rs4285184 del gen MGAT1 y la obesidad en adultos del estado de Colima, México. Métodos: Se realizó un estudio caso-control que incluyó a 244 sujetos. Todos ellos fueron agrupados con arreglo a su porcentaje de grasa corporal, determinado mediante impedancia bioeléctrica, y fueron genotipados para el polimorfismo rs4285184 del gen MGAT1 mediante PCR-RFLP. Se analizaron los resultados para buscar su asociación con el porcentaje de grasa corporal. Resultados: El alelo G reflejó una frecuencia del 49,19% y el 38,75% para los casos y controles, respectivamente (p= 0,020) (OR 1,53; IC 95% 1,068-2,193). La frecuencia del genotipo A/G + G/G fue del 75% en los pacientes obesos, cifra significativamente superior en comparación al 57,5% del grupo control (p = 0,004) (OR 2.217; IC 95% 1,287-3,821). Conclusiones: La presencia del polimorfismo rs4285184 del gen MGAT1 incrementó el riesgo de desarrollar grasa corporal asociada a la obesidad en la población mexicana (AU)

Background and objective: Obesity is a factor that contributes to the morbidity of certain diseases and to worldwide mortality. MGAT1 is a glycosyltransferase involved in the synthesis of protein-bound and lipid-bound oligosaccharides and its polymorphisms are possibly involved in the etiology of obesity. We investigated the association of the rs4285184 polymorphism of the MGAT1 gene with obesity in adults in the State of Colima, Mexico. Methods: A case-control study was conducted that included 244 subjects. All of them were grouped according to their percentage of body fat, determined through bioelectrical impedance, and they were genotyped for the rs4285184 polymorphism of the MGAT1 gene through PCR-RFLP. The results were analyzed for their association with the percentage of body fat. Results: The G allele had a frequency of 49.19 and 38.75% for the cases and controls, respectively (P = .020) (OR 1.53; 95% CI 1.068-2.193). The frequency of the A/G + G/G genotype was 75% in the obese patients, which was significantly higher compared with the 57.5% of the control group (P = .004) (OR 2.217; 95% CI 1.287-3.821). Conclusions: The presence of the rs4285184 polymorphism of the MGAT1 gene increased the risk for developing body fat associated with obesity in the Mexican population (AU)

The rs4285184 polymorphism of the MGAT1 gene as a risk factor for obesity in the Mexican population. / Polimorfismo rs4285184 del gen MGAT1 como factor de riesgo de obesidad en la población mexicana.

BACKGROUND AND OBJECTIVE: Obesity is a factor that contributes to the morbidity of certain diseases and to worldwide mortality. MGAT1 is a glycosyltransferase involved in the synthesis of protein-bound and lipid-bound oligosaccharides and its polymorphisms are possibly involved in the etiology of obesity. We investigated the association of the rs4285184 polymorphism of the MGAT1 gene with obesity in adults in the State of Colima, Mexico. METHODS: A case-control study was conducted that included 244 subjects. All of them were grouped according to their percentage of body fat, determined through bioelectrical impedance, and they were genotyped for the rs4285184 polymorphism of the MGAT1 gene through PCR-RFLP. The results were analyzed for their association with the percentage of body fat. RESULTS: The G allele had a frequency of 49.19 and 38.75% for the cases and controls, respectively (P=.020) (OR 1.53; 95% CI 1.068-2.193). The frequency of the A/G+G/G genotype was 75% in the obese patients, which was significantly higher compared with the 57.5% of the control group (P=.004) (OR 2.217; 95% CI 1.287-3.821). CONCLUSIONS: The presence of the rs4285184 polymorphism of the MGAT1 gene increased the risk for developing body fat associated with obesity in the Mexican population.