Pathogenicity of Ethiopian Isolates of Entomopathogenic Fungi against Glossina Morsitans Morsitans .
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Date
1999-05
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Addis Ababa University
Abstract
Fungal pathogens of insects have increasingly shown promise as effective control agents. In
this work pathogenicity of five local isolates, Mefarrhizilllll anisopliae (EE), Mefarrhizilllll
sp. (MM), Beallveria bassiana (FF), B. bassiana (GG), B. bassiana (AK), and two exotic an
isolates, M. anisopliae (ICIPE 30) and B. bassiana ( temporarily coded as Bb) were
determined against laboratory reared Glossina lIIorsifans lIIorsifans. Fifteen days old
cultures of the respective isolates were harvested in sterile distilled water (0.1 % Tween -20).
After determining the concentration of spore suspensions using Neubauer improved
hemocytometer, concentrations were adjusted to 1 X 108
( the screening concentration used).
Adult flies, less than a week old, were exposed to spore suspensions. Flies were chilled at
1°c for seven minutes prior to exposure. Flies were then exposed to the spores by dipping
them in the suspension for 15 seconds, after which they were recovered and put back to their
cages and to the insectary (70% RH, 25° C). Mortality was recorded for a maximum
duration of 20 days. Among the Mefarrhizilllll species, MefarrhiziulII EE has demonstrated
the highest performance (96.67%), followed by MefarrhiziulII ICIPE 30 (90.00%), and
Mefarri1izillll1 MM (73.33%). The differences were not significant (P> 0.05). Among the
B.bassiana isolates the Kenyan isolate has performed the best (81.67%). Beallveria FF,
Beallveria GG, Beallveria AK, have shown per cent moralities 75.00%, 63.33%, 53.33%,
respectively. The difference between Beallveria FF and Beallveria Bb was not significant
(P<0.05) while the difference between Beallveria Bb and Beallveria GG was significant (P<
0.05). All, but Beallveria GG, were significantly better than Beallveria AK (P< 0.05). Spore
production for Mefarri1izilllll MM and }.Iefarrhizilllll EE was determined on solid substrates,
whole grains of rice, wheat, barley and sorghum. Both isolates have grown best on rice giving a yield of 1.42 X 109 spores/gram of rice for Metal'l'i1izilllll MM and 1.62 X 109 spore/
gram of rice for Metal'l'i1izilllll EE. The next highest yield was on sorghum, 3.10 X 108
spores/gram for Metal'l'i1izilllll MM and 2.25 X \0' spores/gram of wheat for EE. No
correlation was observed between moisture content and the spore yield of grains. Mass
production and utilization of selected fungal pathogens against tsetse as a bioinsecticide as a
component of Integrated Pest Management is recommended.
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Biology