supervisors dr. christine bii (phd) dr. ciira kiiyukia
TRANSCRIPT
TONUI K JOSEPHAT
MSC. STUDENT
JKUAT- COHES
SUPERVISORS
DR. CHRISTINE BII (PhD)
DR. CIIRA KIIYUKIA (PhD)
2014
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* Introduction
More than 100, 000 moulds spp produce over 300 mycotoxins contaminanting food grains
Genera Aspergillus, Penicillium, and Fusarium major contaminants of maize
Produce aflatoxins, ochratoxins and Fumonisins with toxic and carcinogenic potential
Fungicides are chemical compounds against fungi
They affect fungal nucleic acid and sterol biosynthesis, mitosis and cell division, respiration etc.
Several bacterial and fungal antagonists have been developed for the control of Mycotoxigenic fungi
Mycotoxins cause health and economic problems in the
world affecting humans, animals and the environment
Aspergillus flavus and A. parasiticus producing
Aflatoxins are a major problem in Kenya
Largest aflatoxicosis outbreak in 2004 resulted in 125
deaths & 317 cases in Eastern province, Kenya
Tones of maize grain yields have been destroyed
intermittently
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General objective
To determine the susceptibility of mycotoxigenic
fungi to some commercial fungicides as a potential
for the control of mycotoxin infestation in maize
Specific Objectives
1.To isolate and identify mycotoxigenic fungi
affecting maize grains from Machakos, Nairobi,
Mombasa, Kisumu and Kitale.
2.To determine the susceptibility of the
mycotoxigenic fungal isolates to Atracol, Milraz,
Mistress and Victory fungicides.
* Objectives
Study design A laboratory based cross sectional study.
A total of 138 maize samples from the five sites were collected
Conducted at KEMRI Center for Microbiology Research- Mycology Laboratory
Procedures Fungicides diluted according to manufacturers instructions
Fungicide was applied onto four maize Kernels and inoculated on SDA media, incubated at 30oC for 72 hours for fungal growth.
Fungal growth identified morphologically (Microscopic and Macroscopic features) and scored to determine percentage Infestation
Activity of fungicides was determined by Disk Diffusion
* Materials and Methods
* Results
Percentage fungal infestation of maize from different
regions in Kenya following treatment of grains with
fungicides
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Infestation
rates on
maize
Type of fungicide used
Categories MILRAZ MISTRESS VICTORY ANTRACOL CONTROL
0 % within type of
fungicide used
10%
n=14
26%
N=35
34%
N=47
14%
N=19
0%
N=0
25 % within type of
fungicide used
21%
N=29
27%
N=37
19%
N=26
24%
N=33
4%
N=5
50 % within type of
fungicide used
12%
N=17
12%
N=17
18%
N=25
15%
N=21
5%
N=7
75 % within type of
fungicide used
17%
N=23
14%
N=19
8%
N=11
8%
N=11
8%
N=11
100 % within type of
fungicide used
40%
N=55
22%
N=30
21%
N=29
39%
N=54
83%
N=115
Total % within type of
fungicide used
100%
n=138
100%
N=138
100%
N=138
100%
N=138
100%
n=138
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Plate A . Aspergillus niger Plate B. Fusarium and A. flavus
Plate C. Heavily infested untreated
control and treated maize Plate A . Aspergillus
flavus infested maize
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Maize from the five regions were contaminated by mycotoxin producing moulds of the genera Aspergillus spp, Fusarium spp and Penicillium spp.
There was a significant difference p<0.05 in the activity of the four fungicides.
Generally, a significant percentage of maize treated with Mistress and Victory (n=35) and (n=47) respectively were less infested.
The two fungicides were more effective in reducing the fungal infestation on the treated maize samples.
N=55 and N=54 samples treated with Milraz and Antracol respectively had 100% infestation compared to those treated with Victory and Mistress Fungicides (n=29) and (n=30) respectively.
* Discussion
Some isolates of A. flavus, Fusarium spp and Penicillium
spp exhibited resistance to at least one of the test fungicides.
Shown by overgrowth of the mould on fungicide
impregnated disks and absence of a zone of inhibition
This is indicative of emerging resistance to commercial
fungicides.
However, more studies on the emerging resistance to more
fungicides country wide may be necessary.
* Discussion Cont..
The four test fungicides were effective in reducing fungal infestation of maize a potential for mycotoxin control
Further evaluation to ascertain their field efficacy needed.
Some isolates showed resistance to the test fungicides probably due to irrational use of fungicides.
Emerging triazole resistance in A. fumigatus linked to azole antifungals used in agriculture.
Calls for rational use of fungicides in agriculture to avoid emerging resistance in clinical practice
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We acknowledge Kenya Medical Research
Institute (KEMRI) for approval and funding for
this work under mycotoxin surveillance program.
We also acknowledge the Jomo Kenyatta
University of Agriculture and Technology (JKUAT)
for reviewing this work
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