The insecticidal potential of neorautanenia mitis (a.ritch) against prostephanus truncates (horn) in stored maize
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Date
2011
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Publisher
Sokoine University of Agriculture
Abstract
This study was carried out to evaluate the insecticidal potential of Neorautanenia
milis to the Larger Grain Borers Prostephanus truncatus (Hom) (Coleoptera:
Bostrychidae) and its mammalian toxicity. Laboratory studies were conducted to
asses the efficacy and the basic mode of action of N. milis on P. truncatus. Further
studies were conducted to asses the toxicity of N. milis on mammals using rats
(Mastomys natalensis). The efficacy was assessed at six rates (0, 1, 2, 5, 7 and 10%
w/w N. milis in 50g of maize grains) with 5 replications. The repellency was
evaluated in the choice bioassay at five rates (1,5, 10, 15 and 20% w/w N. milis in
50g of maize grains) in 5 replications. The contact mode of action was evaluated
using Student’s t or t-test. Anti-oviposition was evaluated in non choice bioassay
system at six rates (0, 1, 2, 5, 7 and 10% w/w N. milis in 50g of maize grains) in 3
replications. Actelic super dust at a rate of 0.05g in 1kg of maize was also used for
comparison. Mammalian toxicity was evaluated by exposing rats to six rates (0, 5,
12.5,25, 50 and 75% w/w N. milis in Broiler mash) in 6 replications. The lethal dose
(LD5q) was determined by the graphical method of Miller and Tainter. Split-plot
arrangement in a Complete Randomized Design (CRD) was used while Two-way
ANOVA was used in the analysis of data. The results showed that N. milis powder
and liquid extracts were statistically significant (p<0.05) in reducing the number of
damaged grains. Repellency and ant-oviposition are presumed to be the key mode of
action of N. mitis. The study indicated that the plant tuber is toxic to rats, therefore
care should be exercised during the preparation and handling of the food stuff
treated with N. mitis.
Description
A dissertation submitted in partial fulfillment of the requirements for the degree of master of science in crop science
Keywords
Maize, Zea mays L., Neorautanenia mitis, Against prostephanus truncates, Insecticidal potential