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Banana weevil resistance in musa and prospects for genetic improvement
A. Kiggundu,
C.S. Gold, M.T. Labuschagne, D. Vuylsteke, S. Louw, A. Hassanali &
W. Tushemereirwe
The
banana weevil Cosmopolites
sordidus (Germar) is the most important insect pest of highland
banana and plantain in Africa. The larvae bore into the corm, reducing
nutrient uptake and weakening the stability of the plant. Attack can
result in poor crop establishment, plant loss, reduced bunch weight and
shortened plantation life. Host
plant resistance offers the possibility of controlling banana weevil on
small-scale farms within an integrated pest management (IPM)
perspective. To identify sources of weevil resistance within the
available Musa germplasm, 45
clones were screened over four crop cycles in Uganda. The results
suggested that East African highland bananas (genome group AAA-EA),
plantains (AAB), and plantain-derived hybrids were the most susceptible
groups to weevil attack. Although some variability existed within these
groups, no clones could be considered resistant. These were followed by
ABB bananas (cvs Kayinja and Bluggoe), banana-derived hybrids, AB
bananas (cvs Ndiizi and Kisubi), AAA (cvs Yangambi-Km5, Cavendish and
Gross Michel). The highest levels of resistance were observed in
non-cultivated banana hybrids TMB2x7197-2, TMB2x8075-7, the wild diploid
banana Calcutta-4 (AA), Yangambi-Km5, Kayinja and the tetrapolid FHIA-03
(AABB). These were considered the best sources of resistance for a
weevil resistance-breeding programme, with the two hybrids used as
improved male parents. Weevil resistance was attributable to a range of
antibiotic factors, including biochemical compounds, corm dry matter
content (representing corm hardness), resin/sap production and suckering
ability. Preliminary investigations into the chemical basis of
resistance using high-performance liquid chromatography profiles of corm
extracts indicated that compounds were present in some resistant
cultivars (especially those with a B genome) that negatively correlated
with weevil damage. Two active fractions causing weevil mortality from
the cultivar Kayinja were found to be highly polar.
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