Evaluation of the Potential of Native Fungal Isolates for Greater (Galleria Mellonella) and Lesser (Achroia Grisella) Wax Moths
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Date
2002-12
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Addis Ababa University
Abstract
The effects of six fungal isolates; DLCO-AA-S, DLCO-AA-14, IlTA 18, IMI 330189, DLCOAA-
83 and DLCO-AA-I09 were evaluated in the laboratOlY for their pathogenicity to adults,
Sth and 6th lalval instars of both the greater wax moth (Galleria l1lellollella) and lesser wax
moth (Achroia grisella). Conidial dilutions were prepared in O.S% Tween 80. The adults of
both species were treated by spraying while dipping the lalvae in varied fungal concentrations
ranging from 2xl04 to 2xlO7 conidia/m!. Assessments of lalval infection of both the greater
and lesser wax moth was made daily for 14 days before entering the pupal stage after
treatment. MOltality assessment for the lesser wax moth adults was made daily for 8 days post
treatment. Adults of both the greater and lesser wax moths were found to be susceptible to all
fungal isolates and concentrations, ranging from 2xl04 to 2xl07 conidia/m!. Comparison of
mortality results in adults of the greater wax moth at 2xl04 conidia/ml revealed that infection
of over 90% could be achieved in 13 days after inoculation. Similar comparison with the
adults of the lesser wax moth showed that over 78% mortality could be achieved by day 8 after
treatment except isolate IMI33089 that caused low mOltality of 67.0S%. Comparison of
mOttality results of the Sth larval instars of both species of wax moth at 2xl07 conidia/ml
showed varying degrees of vimlence among the fungal isolates. With the Sth lalval instars of
the greater wax moth, isolate IITA 18 caused percentage mOttality of 68.S2% while with
isolates DLCO-AA-S and DLCO-AA-14 a cumulative percentage mortality of61.11 % was
recorded in the lesser wax moth by day 14 of post treatment. Low mortality in the Sth larval
instars of both species was recorded with isolate 1MI 330189. With the greater wax moths Sth
lalval instars, mortality in the control was less than 2 % while in the lesser it was less than 4%.
Results on percentage emergence of the adults from pupae of the greater wax moth adults
showed no significant difference (P > O.OS) between the different fungal isolates and controls.
With the lesser wax moth a slight difference in emergence of adults from pupae was observed
between 2xlO7 conidia/ml and the controls. With all fungal isolates and concentrations used,
percentage emergence of over 86.1 % was obselved in the greater and lesser adults. This
showed that, the isolates at the different fungal concentrations had no effect all adult
emergence when applied on the 6th instars. LaboratOlY experiments were also conducted to
investigate host specificity of two isolates of Metarlzizilll1l spp (DLCO-AA-83 and IMI
330189) and I Beallveria spp (UTA 18) all deuteromyceteentomopathogenic fungi that were tested as entomopathogenic agents against the honeybees
(Apis melli/era (Ethiopian race). Each isolate was applied topically by spraying 10mi of2x107
conidia/ml into the beehives. Isolate UTA 18 caused 0.5% moriality of the treated surface
sterilized honeybees, isolate DLCO-AA-83 resulted in 1% mortality of the treated sUiface
sterilized honeybees and isolate IMI 330189 had no effect on the honeybees. In cases were
infection with the applied fungal isolates occurred, fungal growth on the cadavers was
observed after surface sterilization. Therefore, the present study confirm the pathogenicity of
all the tested isolates against the adu Its of the greater and lesser wax moths and 4 of these
isolates in i.e. isolates in degree of virulence. Isolates UTA 18, DLCO-AA-14, DDLCO-AA-5
and D LCO-AA-83 for the greater wax moth while isolates DLCO-AA-5, D LCO-AA-14 &
DLCO-AA-83 and isolate UTA 18 for the lesser 5th larval instars as potential microbial control
agents for the management of the greater and lesser wax moths.
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Biology