Prevalence and geographical distribution of Nosema apis and Nosema ceranae in apiaries of Northwest Mexico using a duplex real-time PCR with melting-curve analysis

Abstract

In many rural regions of Mexico, beekeeping is an important socioeconomic activity which is currently facing various health issues, being the main one the presence of infectious diseases. The aim of our study was to optimize a duplex Eva Green RT-PCR assay along with melting-curve analysis to detect and differentiate Nosema apis from Nosema ceranae infection in Apis mellifera. At four locations in Northwest Mexico 765 samples from 76 apiaries were tested using a RT-PCR and melting-curve analysis. Infection was detected in all the four geographical regions under study. Overall, 87.32% samples resulted positive for N. apis, 12.68% for N. ceranae and 10.20% resulted co-infected with both microsporidians. The Mexicali valley had the highest prevalence of N. apis with 56.68% positive apiaries, while in Ensenada the lowest prevalence was found with 7.89% positive apiaries. The highest prevalence of N. ceranae was detected in Mexicali (15.79%), while Tijuana and San Luis Rio Colorado showed the lowest prevalence with 1.32%, respectively. Our work indicates a wide spread of nosemosis in all the four geographical regions with a marked dominion of N. apis. The RT-PCR assay resulted highly specific and accurate for the detection of N. apis and N. ceranae and could provide a rapid and accurate diagnostic tool for the simultaneous detection and discrimination of both microsporidians. It can also be used for clinical diagnostics and disease surveillance and to evaluate the effectiveness of the measures for control and prevention of nosemosis in the Northwest corner of Mexico.