Insect pathology -the early years
Population biology of Beauveria
Dave Chandler, Gill Davidson
University of Warwick
Anamorphic Ascomycete Entomopathogenic fungi
• Widespread in nature, especially soil.
• Range of species, different properties.
• Used as inundative biopesticides.
• Can be valuable components of IPM.
Chemical clones or bio-control agents?
• Inundative biopesticides: development = chemical model.
• Ignoring ecological attributes (Waage)– numerical response,
– trade offs,
– conservation control.
• Lack of knowledge: affects biocontrol efficacy & environmental risk evaluation.
Ascomycete entomopathogenic fungi
• Natural abundance? Diversity? Ecosystem function?
• Are they ecologically obligate pathogens?
• Determinants of population structure?
• Population dynamics?
• How does virulence evolve?
• Lack meaningful species definitions.
• Theoretical framework for predicting environmental (non target) impacts of biocontrol releases.
Work outline
• Studying natural popns. of fungi in soils, esp. Beauveria.
– Bidochka : biogeography of Beauveria & Metarhizium.
– Rehner: Beauveria phylogeny.
• Expt 1:– Examined Beauveria from culture collection: collected
from UK woodland & farm grassland.
• Expt 2:
– Sampling at a single farm site.
Galleria bait method
• Culture collection: Beauveria isolates from 9 woods & 11 grasslands.– Devon– Somerset– Gloucestershire– Herefordshire– Shropshire– Berkshire– Warwickshire– Leicestershire
Experiment 1: Beauveria biogeography?: national scale
• Culture collection: – Isolates from each location. – 117 total, 85 wood, 32 grass.
• Sequence data:– EF1a– 28s rDNA gp I intron– Beta tubulin, rDNA ITS– DNA lyase, Beta locus– Micro satellites.
Beauveria biogeography: national scale
EF1a woods & grassland(includes 1 sequence each from Rehner clades A – F)
B. scarabaeicola EFCC2533
D (B. caledonica) none
F (B. amorpha) none
E (Cordyceps sp.) none
A :28/56 from woods (exp 41/56)
100
100
100
63
98
88
100B: 20/20 from woods (exp 15/20)
C: 37 / 41 from woods (exp 30/41)
clustal W, distance (NJ)
Chi sq : habitat effect : p < 0.001 (pearson = 28, 2 df)
Stewardship12 ha
hed
ger
ow
Arable7 ha
Grassland 10 ha
Expt 2: Fungi from different habitats in close proximity: Warwick Dept. farm
Deep slade
Long close
Water meadows
Expt 2: Fungi from different habitats in close proximity
samples Beau Met P. fa P. fu Lec
arable 506 16 1 1 0 0
steward 240 28 0.5 0 0 0
grass 150 55 1 2 1 1
hedge 250 34 0 5 11 0
all 1146 28 0.6 2 3 0.3
Frequency of occurrence (%)
Chi square (pearson) 68.7, 9 df, p < 0.001
EF1a Warwick dept farm
Constructed tree (NJ, distance) with Beauveria isolates:Hedgerow 24Arable 26Stewardship 23Grassland 26
Total 99
EF1a Warwick dept. farm: hedge vs. fields(includes 1 sequence each from Rehner clades A – F)
B. scarabaeicola EFCC2533
D (B. caledonica) none
F (B. amorpha) none
E (Cordyceps sp.) none
A :7/77 from hedge (exp 19/77)
100
100
100
64
97
96
100B: 1/2 from hedge
C: 16 / 20 from hedge (exp 5/20)
clustal W, distance (NJ)
Chi sq : habitat effect : p < 0.001 (pearson = 47, 6 df)
Simplified conclusions
• Genetic groups in Beauveria have different habitat preferences. Why?
• Warwick farm study:– Habitat type affects frequency of occurrence
of fungi.– Diff genera have diff habitat preferences?
Why does this matter? • Bio-prospecting.
• Conservation control (habitat manipulation).
• Informs risk assessment.
• Generation & maintenance of diversity in an ‘asexual’ organism.
acknowledgements• USDA Steve Rehner
Thanks for your attention!