ABSTRACT
Objective To investigate the genes involved in Wolbachia-induced cytoplasmic incompatibility among three natural populations of Culex pipiens pallens in eastern China, so as to provide insights into the development of preventive and control measures for mosquito-borne diseases based on Wolbachia. Methods The cytoplasmic incompatibility was tested among three natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province using reciprocal crosses. Wolbachia infection was detected in C. pipiens pallens using a PCR assay, and the expression of Wolbachia wsp and WD0513 genes was quantified using a fluorescent quantitative real-time PCR (qPCR) assay. Results Bidirectional compatibility was found between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (t = 0.57 and 0.15, both P values > 0.05), while bidirectional incompatibility was seen between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (t = 63.81 and 43.51, both P values < 0.01), and between the natural populations of C. pipiens pallens collected from Nanjing of Jiangsu Province and Tangkou of Shandong Province (t = 39.62 and 43.12, both P values < 0.01). Wolbachia wsp gene was amplified in all three natural populations of C. pipiens pallens, and qPCR assay detected no significant difference in the Wolbachia wsp gene expression among the three natural populations of C. pipiens pallens (F = 2.15, P > 0.05). In addition, there was no significant difference in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Nanjing of Jiangsu Province (q = 8.42, P < 0.05) or between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (q = 7.84, P < 0.05); however, there was a significant difference detected in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (q = 0.40, P > 0.05). Conclusions Different Wolbachia numbers are detected in natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province, and WD0513 gene may be involved in the Wolbachia-induced cytoplasmic incompatibility among three natural populations of C. pipiens pallens.
ABSTRACT
Tagosodes orizicolus (Homoptera: Delphacidae) is one of the main constraints of the rice production in the Neotropics. This planthopper produces severe damages as a phloem feeder, causes mechanical injury during oviposition and vectors the rice hoja blanca virus (RHBV). The main objective of this study was to determine the genetic diversity of T. orizicolus populations from three rice growing regions of Costa Rica, using RAPDs. Individuals from Guanacaste, Parrita, San Carlos and Cali-Colombia, as outgroup, were analyzed using the random primers. Phenetic relationships revealed that the Costa Rican populations were clearly separated from Cali-Colombia, sharing less than 25% similarity. Costa Rican populations were divided into two main branches separated at 30% similarity. The first branch included Guanacaste and San Carlos and the second displayed Parrita. In relation to similarity indexes within groups, the Guanacaste cluster showed the highest (over 50%) and Cali-Colombia was the most diverse (28%). The correspondence analysis confirmed the clusters of the phenogram and showed close interactions between the Parrita and San Carlos populations. The genetic separation observed could be the result of the geographic isolation among populations, but it could also be explained by the infection with the rickettsia Wolbachia pipientis. This bacterium causes cytoplasmic incompatibility in its host, which results in non-viable progeny when infected males mate with non-infected females, or when insects hosting different strains of Wolbachia mate. Then, a search for Wolbachia in previously described populations of T orizicolus was initiated. The presence of the bacteria was analyzed by PCR with 16S rDNA-specific primers for Wolbachia. The PCR analyses revealed infections of 86% in the population of San Carlos, 96% in Guanacaste, 37% in Parrita and 100% in Cali-Colombia. Crosses between individuals of T. orizicolus from Parrita and Guanacaste were performed for testing...