Genetic diversity in banana weevil Cosmopolites sordidus, populations in Banana growing regions of the world
Genetic variability in banana weevil populations was analyzed in a large number of samples obtained from 15 banana growing tropical countries using random amplified polymorphism DNA (RAPD). A total of 46 RAPD markers were studied. Within polymorphism as measured by percentage of polymorphic RAPDs, varied between 78.3% and 97.8%. Genetic variability was measured using Shannon's information index and partitioned into between and within populations components. Overall, genetic variation among C. sordidus populations was (Hsp-Hpop)/ Hsp = 25.3%. The genetic diversity for the species (Hsp) was 83.4%. Mean of within population value (Hpop) for all populations was 62.3%. The total genetic diversity was explained by high variation among populations (mean Gst = 0.213), which is consistent with low gene flow among populations (Nm=0.8 I I). High between population genetic variation observed in this study could be explained by limited migration due to restricted mobility and monophagy in banana weevils. In a parallel study PCR-RFLP analysis was used to differentiate the CO 1 mtDNA of 19 populations of banana weevil. The PCR-RFLP method produced unambiguous profiles that differentiated certain populations from others. In another study, the genetic variability in weevil populations was analyzed in samples obtained from 15 sites in banana growing regions of Uganda. Although the weevil populations in this case were very similar genetically, some variability was observed. The results clearly show genetic diversity in banana weevil.