Infection density of Wolbachia and incompatibility level in two planthopper species, Laodelphax striatellus and Sogatella furcifera

Wolbachia, a bacterial endosymbiote of arthropods, causes cytoplasmic incom patibility (CI) in many insect species. CI traits were studied in two plant hopper species. Laodelphax striatellus and Sogatella furcifera. and Wolbach ia densities in these planthopper species were calculated by quantitative P CR methods. The CI level of L. striatellus was quite high and even aged mal es strongly caused CI. In contrast, S. furcifera showed partial CI, and mal es lost their ability to cause CI with age. Wolbachia infecting these two p lanthopper species were the same with respect to the nucleotide sequences o f Wolbachia genes. 16S rDNA. ftsZ gene, groE genes, and wsp gene. Two metho ds for quantitative PCR, one using a DNA sequencer and the other a real-tim e sequence detection system, were established to calculate the amount of Wo lbachia in the planthoppers. The density of Wolbachia in S. furcifera males was quite low. The difference in CI levels between the two planthopper spe cies seems to be due to different amounts of I Wolbachia infecting males. ( C) 2001 Elsevier Science Ltd. All rights reserved.