Abstract

BackgroundThe banana weevil Cosmopolites sordidus (Germar) is a major production constraint of bananas and plantains (Musa spp.) in the world. Differences in damage levels and pesticide response across regions led to the postulation that there might be considerable variation between banana weevil populations (biotypes) with varying levels of virulence. One of the most sustainable options for banana weevil control is the use of host plant resistance. While new resistant varieties are being developed through both conventional crossbreeding and biotechnology, there is a need to assess the genetic variation of banana weevil populations from eastern, central, southern, southwestern and midwest regions of Uganda to determine whether there are biotypes with different virulence levels. This would help guide new control strategies to target all the possible biotypes. The amplified fragment length polymorphism (AFLP) technique was used to analyze population genetic diversity using four primer combinations (EcoRI/MSeI).ResultsAnalysis of molecular variance results presented no evidence to support significant genetic variability among the banana weevil populations from eastern, central, southern, southwestern and midwest regions. Practically, all the genetic variation was found to reside within populations (97% for sites and 98% for regions), with only approximately 3% and 2% residing among populations of sites and regions, respectively.Conclusions and recommendationsAFLP markers clustered the banana weevils into two distinct populations consequently supporting the hypothesis of possible presence of banana weevil biotypes in Uganda. However, attempts should be made to make follow-up studies on the seemingly unique population of eastern Uganda using more robust molecular techniques to establish whether the eastern Uganda population constitutes a different biotype.

Highlights

  • The banana weevil Cosmopolites sordidus (Germar) is a major production constraint of bananas and plantains (Musa spp.) in the world

  • This study addressed the need to evaluate the variation among the banana weevil populations so as to develop control measures that will target all biotypes in the banana growing regions if confirmed to exist

  • Analysis of molecular variance (AMOVA) The results of analysis of molecular variance (AMOVA) indicated that the difference among groups was not significant (P = 0.897) for the 22 populations and (P = 0.894) for the five regions while the amounts of genetic variation within population were significant at P = 0.036 for the 22 populations and P = 0.023 for the five regions (Tables 5, 6)

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Summary

Introduction

The banana weevil Cosmopolites sordidus (Germar) is a major production constraint of bananas and plantains (Musa spp.) in the world. While new resistant varieties are being developed through both conventional crossbreeding and biotechnology, there is a need to assess the genetic variation of banana weevil populations from eastern, central, southern, southwestern and midwest regions of Uganda to determine whether there are biotypes with different virulence levels This would help guide new control strategies to target all the possible biotypes. Twesigye et al Agric & Food Secur (2018) 7:76 and up to 100%, respectively, were reported by [4, 5], while in Mbarara, Bushenyi, Ntungamo and Kabale districts, there was negligible yield loss This has led to the postulation that there is a considerable variation between banana weevil populations from different regions of Uganda with varying levels of virulence. Screening trials suggest that many resistant Musa clones do exist mostly among non-cultivated wild diploids and that antibiosis is the predominant means of resistance in these clones

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