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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. [ABSTRACT FROM AUTHOR]

Simple Summary: The mite Varroa destructor, the viruses that it transmits, and the fungus Nosema ceranae, are among the main drivers of honey bee (Apis mellifera) colony losses. Honey bees are the main pollinators of flowering plants and contribute to one-third of food produced. Therefore, it is important to find out if there are honey bee strains that defend themselves better against these agents of disease. This study was conducted to determine if Africanized honey bees are more resistant than European honey bees to parasitic and viral diseases, as well as if their resistance is affected by climate. Consequently, the presence and levels of parasites and viruses was determined in 365 honey bee colonies of European or African ancestry in subtropical and temperate regions of Mexico. Varroa and Nosema were the most and least frequently found parasites (95% and 15%, respectively). Deformed wing virus (DWV) and black queen cell virus (BQCV) were the only viruses detected at frequencies of 38% and 66%, respectively. Varroa, DWV, and BQCV, were found at higher levels in colonies of European ancestry than in colonies of African ancestry. However, there were no effects of climate. Therefore, it is concluded that bee strain, but not climate, influences the resistance of honey bees to DWV, BQCV, and Varroa. This study was conducted to analyze the effect of genotype and climate on the resistance of honey bee (Apis mellifera) colonies to parasitic and viral diseases. The prevalence and intensity of parasitism by Varroa destructor, or infection by Nosema spp., and four honey bee viruses were determined in 365 colonies of predominantly European or African ancestry (descendants of A. m. scutellata) in subtropical and temperate regions of Mexico. Varroa destructor was the most prevalent parasite (95%), whilst N. ceranae was the least prevalent parasite (15%). Deformed wing virus (DWV) and black queen cell virus (BQCV) were the only viruses detected, at frequencies of 38% and 66%, respectively. Varroa destructor was significantly more prevalent in colonies of European ancestry (p < 0.05), and the intensity of parasitism by V. destructor or infection by DWV and BQCV was also significantly higher in colonies of European descent than in African descent colonies (p < 0.01), although no genotype–parasite associations were found for N. ceranae. Additionally, significant and positive correlations were found between V. destructor and DWV levels, and the abundance of these pathogens was negatively correlated with the African ancestry of colonies (p < 0.01). However, there were no significant effects of environment on parasitism or infection intensity for the colonies of both genotypes. Therefore, it is concluded that the genotype of honey bee colonies, but not climate, influences their resistance to DWV, BQCV, and V. destructor. [ABSTRACT FROM AUTHOR]

• Two out of six honey bee viruses were detected in tropical bee species. • DWV and BQCV infect and multiply in several tropical bee species. • Honey bee viruses could be detrimental to the health of multiple bee species. 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. [ABSTRACT FROM AUTHOR]

Jalisco is one of the main honey bee producing states in Mexico. However, information on the parasitoses that affect the productivity of honey bee (Apis mellifera) colonies in the state is limited and addresses only a few regions. The objective of this study was to determine the prevalence and intensity of two parasitic diseases of Apis mellifera--varroosis (Varroa destructor) and nosemosis (Vairimorpha spp.)--in six regions of Jalisco. Bees from 365 colonies collected during the spring were analyzed. Varroosis was the most frequent parasitosis (90 %), and nosemosis was the least frequent (15 %). The infestation or infection levels of these parasitoses were generally low: <5 % (mites per 100 bees) for varroosis, and <310,000 spores/bee for nosemosis. The regions with the highest prevalence and intensity of V. destructor were the Highlands, the Center, and the South, while infections by Vairimorpha ceranae --the only species of the fungus found-- were significantly higher in the Southeastern and Southern regions. It is advisable to carry out epidemiological studies at other times of the year in order to detect possible seasonal effects of parasitoses for the purpose of designing strategies for their control. [ABSTRACT FROM AUTHOR]