Monitoring the Season-Prevalence Relationship of Vairimorpha ceranae in Honey Bees (Apis mellifera) over One Year and the Primary Assessment of Probiotic Treatment in Taichung, Taiwan.

Microsporidiosis, which is caused by the pathogen Vairimorpha ceranae, is a prevalent disease in the honey bee (Apis mellifera) and might lead to significant adult honey bee mortality. In this study, we conducted an annual survey of the mature spore load of V. ceranae in the guts of nurse bees and forager bees in the apiary of National Chung Hsing University (NCHU) in Taiwan. The results indicated that, on average, honey bees hosted approximately 2.13 × 106 mature spore counts (MSCs)/bee in their guts throughout the entire year. The highest number of MSCs was 6.28 × 106 MSCs/bee, which occurred in April 2020, and the lowest number of MSCs was 5.08 × 105 MSCs/bee, which occurred in November 2020. Furthermore, the guts of forager bees had significantly higher (>58%) MSCs than those of nurse bees. To evaluate the potential of the probiotic to treat microsporidiosis, the lactic acid bacterium Leuconostoc mesenteroides TBE-8 was applied to honey bee colonies. A significant reduction (>53%) in MSCs following probiotic treatment was observed, indicating the potential of probiotic treatment for managing microsporidiosis. This research provided information on V. ceranae MSCs in the honey bee gut at NCHU in Taiwan and the MSCs' correlation with the annual season. Furthermore, a potential probiotic treatment for microsporidiosis was assessed for future management.

Low-Level Fluvalinate Treatment in the Larval Stage Induces Impaired Olfactory Associative Behavior of Honey Bee Workers in the Field.

Fluvalinate is a widely used insecticide for varroa mite control in apiculture. While most beekeepers have ignored the effects of low levels of fluvalinate on bees, this study aims to demonstrate its effects at very low concentrations. We first used fluvalinate doses ranging from 0.4 to 400 ng/larva to monitor the capping, pupation, and emergence rates of larval bees. Second, we used the honey bees' proboscis extension reflex reaction to test the learning ability of adult bees that were exposed to fluvalinate doses from 0.004 to 4 ng/larva in the larval stage. The brood-capped rate of larvae decreased dramatically when the dose was increased to 40 ng/larva. Although no significant effect was observed on brood-capping, pupation, and eclosion rates with a dose of 4 ng/larva, we found that the olfactory associative behavior of adult bees was impaired when they were treated with sublethal doses from 0.004 to 4 ng/larva in the larval stage. These findings suggest that a sublethal dose of fluvalinate given to larvae affects the subsequent associative ability of adult honey bee workers. Thus, a very low dose may affect the survival conditions of the entire colony.

Revealing Pesticide Residues Under High Pesticide Stress in Taiwan's Agricultural Environment Probed by Fresh Honey Bee (Hymenoptera: Apidae) Pollen.

Significant pesticide residues are among the most serious problems for sustainable agriculture. In the beekeeping environment, pesticides not only impact a honey bee's survival, but they also contaminate bee products. Taiwan's agricultural environment has suffered from pesticide stress that was higher than that found in Europe and America. This study deciphered problems of pesticide residues in fresh honey bee pollen samples collected from 14 monitoring apiaries in Taiwan, which reflected significant contaminations within the honey bee population. In total, 155 pollen samples were screened for 232 pesticides, and 56 pesticides were detected. Among the residues, fluvalinate and chlorpyrifos showed the highest concentrations, followed by carbendazim, carbaryl, chlorfenapyr, imidacloprid, ethion, and flufenoxuron. The average frequency of pesticide residues detected in pollen samples was ca. 74.8%. The amounts and types of pesticides were higher in winter and in southwestern Taiwan. Moreover, five of these pollen samples were contaminated with 11-15 pesticides, with average levels between 1,560 and 6,390 µg/kg. Compared with the literature, this study emphasized that pollen gathered by honey bee was highly contaminated with more pesticides in Taiwan than in the America, France, and Spain. The ubiquity of pesticides in the pollen samples was likely due to the field applications of common pesticides. Recently, the Taiwanese government began to improve the pesticide policy. According to the resurvey data in 2016, there were reductions in several pesticide contamination parameters in pollen samples from west to southwest Taiwan. A long-term investigation of pollen pesticide residues should be conducted to inspect pesticides usage in Taiwan's agriculture.