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

Larval mortality is the primary symptom of diseased <i>Apis cerana</i> colonies, often attributed to sacbrood virus (SBV) and <i>Melissococcus plutonius.</i> However, the impact of other common honeybee viruses is frequently overlooked, and their pathogenicity to <i>A. cerana</i> remains poorly understood. To investigate the causes of the increasing disease incidence in <i>A. cerana</i> 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 <i>A. cerana</i> brood through artificial inoculation experiments. Our results demonstrate that, besides SBV and <i>M. plutonius</i>, 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 <i>A. cerana</i> brood, with some individuals able to restrict viral proliferation. Our study highlights the previously unrecognized pathogenicity of IAPV to <i>A. cerana</i> brood, demonstrating that IAPV poses a significant threat similar to SBV and <i>M. plutonius</i>. We emphasize that IAPV should be recognized as an emerging pathogen causing brood disease in <i>A. cerana</i> and managed accordingly in beekeeping practices.