Susceptibility of some maize varieties to the maize weevil sitophilus zeamais (Motschulsky), (Coleoptera: Curculionidae) and effect of some local botanical materials for the suppression of weevil populations.
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Date
2010-07-20
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Abstract
The commonest method of traditional storage pests management among small scale maize farmers in Ghana is the use of botanicals. Earlier studies on the use of plant extract and resistant varieties showed that they minimized insect pest damage to acceptable levels. The objectives of this study were to determine the resistance status of thirteen elite maize varieties (Mamaba (Control), EVDTW99STRQPMCo, Dodzi, FU2090DYFP, TZEEY-PopSTRC4, DORKE SR, DMLSRYQPM, GH90DYFP, FU2080DWF/DPop, TZE-Y-PopDTSTRC4, 2000SYNEEWQPMCo, GH90DWOP and FU2090DWDpop) to Sitophilus zeamais, to identify the potency of some local botanical materials: Piper nigrum L.(black pepper seed powder), Cymbopogon nardus (citronella shoot powder), Carica papaya (pawpaw seed powder), Allium sativum (garlic bulbs paste) and Cymbopogon citrates (lemon grass shoot powder) for the treatment of stored maize and determine their minimum effective dosage for application. In a completely randomized design, ten females of S. zeamais were allowed to oviposit in whole shelled maize varieties for three days and were removed. The resultant emerging weevils that emerged were removed and counted daily without replacement. The mean numbers of weevils that emerged from the 13 maize lines were significantly different among them at (P< 0.05). The varieties exhibited varying degrees of susceptibility and weight loss to the weevil attack with 2000SYNEEWQPMCo producing the least mean number of weevils whilst FU2090DYFP recorded the largest number. Six varieties were resistant and seven were moderately resistant. In olfactometer and potency test of the botanical materials, black pepper, lemon grass, pawpaw seed powder, citronella and garlic showed varying degrees of repellency decreasing in that order as well as their potency. Fifty grammes of black pepper powder in a bag (100kg) of maize was determined as the minimum effective concentration.
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A thesis submitted on June, 2010.