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J. Deera, D. P.
Giga and K. V. Pixley.
2001. Resistance
of maize to the maize weevil: II.
Non-preference.
African
Crop Science Journal 9, 2:431-440, 2001:
II.
Manuscripts
in conference proceedings
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Derera J., K.V. Pixley, and D.P. Giga. 1999.
Inheritance of maize weevil resistance in maize hybrids among maize
lines from Southern Africa, Mexico, and CIMMYT-Zimbabwe. In: CIMMYT
and EARO. Maize Technologies for the Future: Challenges and
Opportunities. Proceedings of the 6th Eastern and Southern Africa
Regional Maize Conference held in Addis Ababa, Ethiopia, 21 – 25
September. CIMMYT, Harare, Zimbabwe.
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Dhliwayo, T. and K.V. Pixley. (In press) Breeding for
Resistance to the Maize Weevil. Is it Feasible? In: CIMMYT and KARI.
Integrated Approaches to Higher Maize Productivity in the New
Millennium. A Proceedings of the 7th Eastern and Southern Africa
Regional Maize Conference and Symposium on Low Nitrogen and Drought
Tolerance in Maize, held in Nairobi, Kenya, 11 – 15 February 2002.
Manuscripts in preparation for refereed journals
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Dhliwayo, T. and K.V. Pixley. Divergent selection for
resistance to maize weevil in six maize populations. (Accepted by Crop Science).
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Dhliwayo, T., K.V. Pixley and V. Kazembe. Combining
ability for resistance to maize weevil among mid-altitude maize
inbreds (work in progress).
RESISTANCE OF MAIZE TO THE MAIZE WEEVIL: I. ANTIBIOSIS
JOHN DERERA1,
KEVIN V. PIXLEY2* and DENASH P. GIGA3
1Corresponding
author, Department of Research & Specialist Services, P. O. Box CY550,
Causeway, Harare, Zimbabwe; Tel./Fax: 263 4 301807, e-mail: K.Pixley@cgiar.org
2CIMMYT-Zimbabwe,
P. O. Box MP163, Mt. Pleasant, Harare, Zimbabwe
3University
of Zimbabwe, P. O. Box MP167, Mt. Pleasant, Harare, Zimbabwe
ABSTRACT:
Resistance to damage by maize weevil (Sitophilus zeamais Motsch.) is
critically important to subsistence farmers world-wide, who typically
store maize grain on-farm. To evaluate grain’s antibiosis effects to
weevil, 18 inbred lines, six each from Southern Africa, Mexico and CIMMYT-Zimbabwe
were mated in sets, according to a North Carolina Design II. Hybrids were
advanced to F2 by controlled full-sib matings. Tests of weevil antibiosis
of grain were conducted under controlled temperature and relative
humidity. Fifty-gram samples of each hybrid and line were infested with 32
unsexed weevils for 10 days. F1 progeny were counted at 2-day intervals
until all progeny had emerged. Some hybrids had detrimental effects
to weevil-biology (antibiosis), as hybrids differed significantly for
adult mortality (0 to 89%), progeny emergence (1 to 188 weevils),
development period (29 to 44 days) and relative index of susceptibility
(0.3 to 11.7). Variation for index of susceptibility (antibiosis) among
hybrids was more in F1 than F2 generation. Additive, non-additive,
and maternal effects were significant in determining weevil resistance for
F1 seed and F2 grain. Variance of GCA effects for lines used as
females was larger than that for lines used as males, suggesting that
breeders developing weevil resistant hybrids should place greatest
emphasis on choice of the female parent. Results indicate that it is
essential to evaluate weevil resistance of F2 grain, because we generally
found no relationship between performance in F1 and F2, and because it is
weevil resistance in F2 that is of practical significance to farmers and
grain merchants.
KEYWORDS:
Maize, maize weevil,
antibiosis, insect resistance, Sitophilus zeamais
RESISTANCE
OF MAIZE TO THE MAIZE WEEVIL: II.
NON-PREFERENCE
JOHN
DERERA1, DENASH P.
GIGA2 and KEVIN V. PIXLEY3*
1Department of Research & Specialist Services, P. O. Box CY550,
Causeway, Harare, Zimbabwe
2University of Zimbabwe, P.O. Box MP167, Mt. Pleasant, Harare, Zimbabwe
3CIMMYT-Zimbabwe, P.O. Box MP163, Mt. Pleasant, Harare, Zimbabwe
*Corresponding
author: Tel./Fax: 263 4 301807, e-mail: K.Pixley@cgiar.org
ABSTRACT:
Although
there have been significant advances in improving maize for grain yield,
progress in developing varieties resistant to the maize weevil (Sitophilus
zeamais Motsch.) has been limited. Fifty-two hybrids were evaluated
against the maize weevil for non-preference in free choice experiments to
study gene action determining inheritance of this mechanism of resistance.
Eighteen inbred lines, six each from southern Africa, Mexico and CIMMYT-Zimbabwe
were used to make the hybrids. Lines were mated among sub-groups of three
each, according to a North Carolina Design II scheme. F2 grain
of the hybrids was evaluated for non-preference resistance under
controlled temperature and relative humidity conditions. Maize weevil
preferred some hybrids, and caused grain weight losses ranging from 0.85
to 8.45% after 70 days of feeding in a free-choice environment with equal
access to all maize genotypes. The maize weevil preferred ‘SR52’, a
local commercial hybrid, that we used as the susceptible check (6.62%
weight loss), and other local hybrids (6.02 to 6.80% weight loss), to
‘Oaxaca 179’ (the resistant check), which incurred a weight loss of
3.50%. Four percent of the experimental hybrids incurred less than 2.0%
grain loss and were classified as resistant, while a further 29% of
hybrids were moderately resistant to weevil attack. General combining
ability effects (GCA) of lines used as male and female parents were
significant (P<0.01) and had similar variance, indicating that, on
average, both parents contributed equally to non-preference resistance to
weevil. Significant specific combining ability (SCA) effects signalled the
importance of non-additive gene action for this trait. Results suggest
that it is possible to develop hybrids with improved non-preference
resistance of F2 grain to maize weevil.
Keywords:
Maize, maize weevil, insect resistance, non-preference,
Sitophilus
zeamais
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