Influence of <Emphasis Type="Italic">Lecanicillium attenuatum</Emphasis> on the development and reproduction of the cotton aphid, <Emphasis Type="Italic">Aphis gossypii</Emphasis> |
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Authors: | Jeong Jun Kim |
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Institution: | (1) Applied Entomology Division, National Institute of Agricultural Science and Technology, Suwon, 441-707, Republic of Korea;(2) Lethbridge Research Centre, Agriculture and Agri-Food Canada, 5403 – 1 Avenue South, Lethbridge, AB, Canada, T1J 4B1 |
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Abstract: | The activity of entomopathogens on insect pests has been investigated for many species but the influence of entomopathogenic
fungi on factors other than mortality relating to population increase has not been frequently studied. The influence of Lecanicillium attenuatum CS625 (=Verticillium lecanii CS625) on development and reproduction of cotton aphid (Aphis gossypii) was investigated. A conidia suspension of the isolate was applied onto first instar nymphs. Increased spore concentration
did not significantly affect each nymphal stage, total nymphal period, pre-reproductive period and the age of first larviposition.
A significant dose effect on reduction of life span, reproductive period and fecundity was observed in 1st and 3rd instars
after spore application. When conidia were applied to 1st instars, life span was significantly reduced to 10.8 and 8.4 days
at 1 × 104 and 1 × 108 conidia/ml, respectively from 12.2 days in the control. During the life span, total fecundity was 41 ± 7.3, 26 ± 0.8 and
22 ± 5.7 nymphs per female at 1 × 104, 1 × 106 and 1 × 108 conidia/ml, respectively compared with 51 ± 2.0 nymphs per untreated female. Reproduction period was also significantly shortened
with increasing spore concentration. Application of spores to 3rd instars showed a similar trend. However, daily fecundity
of individual aphids was not affected by spore dose. It was concluded that the isolate of L.
attenuatum is able to affect populations of cotton aphid by reducing life span and total fecundity as well as by killing the aphids
directly. |
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Keywords: | Aphis gossypii cotton aphid development entomopathogenic fungi fecundity Lecanicillium attenuatum Verticillium lecanii |
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