Pathogenic Detection and Etiological Analysis of White-headed Pupa of Apis cerana

Purpose White-headed pupae of Chinese honeybee is one of the most serious diseases endangering the beekeeping industry. At present, some people believe that the etiology of " white-headed pupae” of Chinese honeybee has not been accurately reported. Therefore, we aimed to find out the cause of this disease.

Method The diseased Apis cerana larvae with " white-headed pupae” were collected from Qinhuangdao, Ankang, and Dandong. The frequently occurring honeybee viruses including CSBV, DWV, BQCV and ABPV, were detected by RT-PCR, and the bacteria were isolated and cultured using blood agar medium. The " white-headed pupae” samples were inoculated and incultured in the blood agar medium under the condition of 37 ℃ for 24 hours, then, colonies of different morphologies, especially colonies with β-hemolymph, were selected for purification culture. The 16S rRNA gene of the isolated bacteria was amplified and sequenced by PCR, and its biochemical characteristics were identified by microbiochemical identification tube. Based on the comprehensive analysis of the etiology of " white-headed pupae”, the regression experiment of Serratia marcescens infection was carried out.

Result No bee virus was found in the samples; 8 strains of bacteria were isolated from the insects in three areas, including S. marcescens, Staphylococcus epidermidis, Serratia liquefaciens, Klebsiella pneumoniae and Bacillus cereus. S. marcescens was detected in all samples. In view of this, the larval infection experiments of S. marcescens were carried out and the results were inoculated with S. marcescens larvae. Unable to pupate and die normally, pathological examination showed pathological changes similar to clinical natural death.

Conclusion Combined with relevant reports, comprehensive analysis of S. marcescens may be the pathogen of " white-headed pupa”, and stress factors are the inducement of " white-headed pupa”. This study laid a foundation for the pathogenic analysis and prevention of " white-headed pupae” disease of Chinese honeybee.