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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/16691
Title: Evaluation of the Potential of Native Fungal Isolates for Greater (Galleria Mellonella) and Lesser (Achroia Grisella) Wax Moths
???metadata.dc.contributor.*???: Dr. Emiru Seyoum
Hellen, Namusana
Issue Date: Dec-2002
Publisher: Addis Ababa University
Abstract: The effects of six fungal isolates; DLCO-AA-5, DLCO-AA-14, IITA 18, IMI 330189, DLCOAA-83 and DLCO-AA-109 were evaluated in the laboratory for their pathogenicity to adults, 5 and 6 larval instars of both the greater wax moth (Galleria mellonella) and lesser wax moth ( Achroia grisella). Conidial dilutions were prepared in 0.5% Tween 80. The adults of both species were treated by spraying while dipping the larvae in varied fungal concentrations ranging from 2xl04 to 2xl07 conidia/ml. Assessments of larval infection of both the greater . and lesser wax moth was made daily for 14 days before entering the pupal stage after treatment. Mortality 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/ml. Comparison of mortality results in adults of the greater wax moth at 2x104 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 mortality of 67.05%. Comparison of mortality results of the 5 larval instars of both species of wax moth at 2x10 conidia/ml showed varying degrees of virulence among the fungal isolates. With the 5th larval instars of the greater wax moth, isolate IITA 18 caused percentage mortality of 68.52% while with isolates DLCO-AA-5 and DLCO-AA-14 a cumulative percentage mortality of 6 1.11% was recorded in the lesser wax moth by day 14 of post treatment. Low mortality in the 5th larval instars of both species was recorded with isolate IMI 330189, With the greater wax moths 5 larval 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 > 0.05) between the different fungal isolates and controls. With the lesser wax moth a slight difference in emergence of adults from pupae was observed between 2x10 conidia/ml and the controls. With all fungal isolates and concentrations used, percentage emergence of over 86.1% was observed in the greater and lesser adults. This showed that, the isolates at the different fungal concentrations had no effect on adult emergence when applied on the 6th instars. Laboratory experiments were also conducted to investigate host specificity of two isolates of Metarhizium spp (DLCO-AA-83 and IMI 330189) and 1 Beauverici spp (IITA 18) all deuteromycete entomopathogenic fungi that were tested as entomopathogenic agents against the honeybees ( Apis mellifera (Ethiopian race). Each isolate was applied topically by spraying 10ml of 2x107 conidia/ml into the beehives. Isolate IITA 18 caused 0.5% mortality of the treated surface sterilized honeybees, isolate DLCO-AA-83 resulted in 1% mortality of the treated surface 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 adults of the greater and lesser wax moths and 4 of these isolates in i.e. isolates in degree of virulence. Isolates IITA 18, DLCO-AA-14, DDLCO-AA-5 and D LCO-AA-83 for the greater wax moth while isolates DLCO-AA-5, DLCO-AA-14 & DLCO-AA-83 and isolate IITA 18 for the lesser 5th larval instars as potential microbial control agents for the management of the greater and lesser wax moths.
Description: A Thesis Submitted to the School of Graduate Studies, Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Biology (Insect Science)
URI: http://hdl.handle.net/123456789/16691
Appears in Collections:Thesis - Biology

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