Degefu, Dawit Tesfaye (2007) A Study on the Potential of Native Entomopathogenic Fungi against Melon/Cotton Aphid, Aphis gossypii Glover (Homoptera: Aphididae). Masters thesis, Addis Ababa University.
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Abstract
The effects of five temperature regimes and five artificial culture media on germination, radial growth and sporulation of four Beauveria and two Metarhizium isolates obtained from various ecological zones of Ethiopia were investigated in vitro. The susceptibility of adult Aphis gossypii to four concentration levels (105, 106, 107 and 108 conidia ml-1) of these fungal isolates was evaluated with direct spraying bioassay at 20, 25 and 300c under laboratory conditions. All experiments were replicated three times using completely randomized design. Germination, radial growth and sporulation of all fungal isolates were slower at 150c than 20, 25 and 300c. At 350c none of the Beauveria isolates were able to germinate after 24 hour post inoculation. A suitable temperature for germination and radial growth was ranged from 20 - 300c for all fungal isolates. The maximum rate of growth per day was obtained at 300c followed by 250c. As regards to artificial culture media, all fungal isolates showed maximum radial growth on OMA. Isolate MM and ICIPE 30 revealed the highest sporulation and fastest germination percentage 60% and 77% after 8 hour on OMA, respectively. The Beauveria isolate, DLCO 105 showed the highest sporulation on SDA and PDA. The maximum rate of growth per day was obtained on OMA with all the fungal isolates. The result of the bioassay showed that at 25 and 300c, all tested isolates with 1 x 108 conidia ml-1 were virulent (73.33 – 93.33% mortality and LT50 ranged from 3.82 - 4.96 days) and (82.22 - 100% mortality and LT50 ranged from 3.22- 4.01 days) to Aphis gossypii, respectively. The Beauveria isolate DLCO 87 had the lowest LC50 value at 20 and 300c and DLCO 41 at 250c.The results of the present study suggest that the potential use of native entomopathogenic fungi as an alternative method to chemical pesticides may hold promise for the management of Aphis gossypii in Ethiopia.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | Q Science > Q Science (General) Q Science > QH Natural history > QH301 Biology Q Science > QK Botany |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 01 Oct 2018 13:04 |
| Last Modified: | 01 Oct 2018 13:04 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/5766 |
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