Israeli Acute Paralysis Virus Is an Emerging Pathogen Contributing to Brood Disease of .

Larval mortality is the primary symptom of diseased colonies, often attributed to sacbrood virus (SBV) and However, the impact of other common honeybee viruses is frequently overlooked, and their pathogenicity to remains poorly understood. To investigate the causes of the increasing disease incidence in brood, we conducted an epidemiological survey, collecting 70 samples from 19 sites across nine provinces in China. Furthermore, we examined the pathogenicity of Israeli acute paralysis virus (IAPV) in brood through artificial inoculation experiments. Our results demonstrate that, besides SBV and , the infection rate and viral load of IAPV in diseased brood are significantly high. Brood artificially inoculated with high concentrations of IAPV exhibited a significant increase in mortality and displayed clinical symptoms similar to those observed in naturally infected colonies. Moreover, a limited resistance to IAPV was observed in brood, with some individuals able to restrict viral proliferation. Our study highlights the previously unrecognized pathogenicity of IAPV to brood, demonstrating that IAPV poses a significant threat similar to SBV and . We emphasize that IAPV should be recognized as an emerging pathogen causing brood disease in and managed accordingly in beekeeping practices.