Ecology of stored grain beetles: How far have we come, what does it mean and what next? Greg Daglish Principal Research Scientist DAFF Queensland biosecurity built on science Cooperative Research Centre for National Plant Biosecurity
Insect ecology Recognised pre-requisite for pest and resistance management (P&RM). What about grain insects in Australia? 5 yr ago large gaps in knowledge, especially field ecology. biosecurity built on science
How far have we come? Two key pests Australian perspective Field ecology What PH3 does to insects biosecurity built on science
Two major pests  Lesser grain borer (LGB) - Rhyzopertha dominica
 Rust-red flour beetle (RFB) - Tribolium castaneum biosecurity built on science
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LGB and RFB are not restricted to the storage environment  Based on studies in multiple regions
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Brookton Depot vs Boyagin Rock Reserve LGB
Beetles trapped
350 300 250 Brookton
200 150
Boyagin
100 50 0
05 A
21 24 13 02 Feb 11 -Ap Sep Nov Ja n ugr-1 2 - 12 -12 -1 1 -1 1 11 Date set biosecurity built on science
Brookton Depot vs Boyagin Rock Reserve RFB
Beetles trapped
25 20 15
Brookton Boyagin
10 5 0
05 A
ug11
24 S
13 02 21 11 No Ap J F a e epv -1 n-1 b- 1 r-1 11 2 2 1 2 Date set biosecurity built on science
Patterns can differ between species
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RFB in central Qld Depot traps (mean Âą SE, n = 4)
1400
1400
1200
1200
Beetles per fortnight
Beetles per fortnight
Non-depot traps (mean Âą SE, n = 5)
1000 800 600 400 200 0 26/2/11
1000 800 600 400 200
17/4/11
6/6/11
26/7/11
14/9/11 Date set
3/11/11
23/12/11
11/2/12
0 26/2/11
17/4/11
6/6/11
26/7/11
14/9/11
3/11/11
23/12/11
11/2/12
Date set
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LGB in central Qld All traps (mean Âą SE, n = 9) 1000
Beetles per fortnight
900 800 700 600 500 400 300 200 100 0
16 / 2/1 1
7/4 /11
27 / 5/1 1
16 / 7/1 1
4/9 /11
24 / 10 / 1
1
13 / 12 / 1
1
1/2 /12
22 / 3/1 2
Date set
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Patterns can differ between regions
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LGB - Qld vs WA
Central Qld (mean Âą SE, n = 9)
Northern WA wheat belt (n = 3)
1000
Beetles per fortnight
Beetles per fortnight
900 800 700 600 500 400 300 200 100 0
16 / 2/1 1
7/4 /11
27 / 5/1 1
16 / 7/1 1
4/9 /11
Date set
24 / 10 / 1
1
13 / 12 / 1
1
1/2 /12
22 / 3/1 2
1000 900 800 700 600 500 400 300 200 100 0
Mingenew Three Springs Coorow
16 F
27 16 24 22 07 04 13 01 Ma Ju lMa Oct Sep Feb Apr Dec eby- 1 r- 12 -1 1 -1 1 11 - 12 -1 1 -1 1 11 1 Date set
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Gene flow
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Sth Qld trapping study
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Evidence of gene flow Neutral DNA markers - No population structure in LGB or RFB at district scale (up to 100 km)
PH3 resistance marker
- ≈ 11% of LGB carried rph2 allele - Silo traps = field traps
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Emigrants
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Emigrants mostly mated, long lived and fecund
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Grain spills as resources
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Grain spills as resources (in progress)  Field study on small spills - Few beetles attracted regardless of whether piled or spread, covered or uncovered.
 Lab study - Species-specific differences in preference for piled or spread wheat. biosecurity built on science
Some beetles have been fumigated
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Fumigation suppresses RFB reproduction R♀ x R♂
Mean number of RFB offspring
120
R♀ x H♂
100
R♀ x S♂ 80
60
40
20
0 Prefumigation
1
2
3
4
5
6
Oviposition week biosecurity built on science
Fumigated RFB females can produce susceptible phenotypes R♀ x S♂: all offspring ‘susceptible’ R♀ x Het♂: 50-60% ‘susceptible’ (same as in unfumigated ♀♀) biosecurity built on science
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What does it mean?  LGB and RFB flight and gene flow data - Flight important
– pests and genes
- Need area wide P&RM approach - Exploit regional and species differences? - e.g. timing of management options biosecurity built on science
What does it mean? PH3 effects on LGB and RFB ecology - Reduced fecundity in surviving ♀♀ - Resistant ♀♀ can pass on susceptible alleles - Re-think development and spread of resistance? biosecurity built on science
What next? Field ecology
– include other pests (e.g. Flat Grain Beetle, Rice Weevil)
Ecological applications suppression
– e.g. pheromones for pest
Potential fitness costs of PH3 resistance e.g. longevity, over-wintering, reproduction
-
Synthesis leading to P&RM strategies and tactics biosecurity built on science
Key Team Members CRC50149
- DAFF Qld – G Daglish, A Ridley, M Rafter, P Burrill, P Collins, D Schlipalius, A Tuck - UQ – G Walter, J Hereward, F Ahmad - DAFWA – R Emery, D Cousins - NSW DPI – J Holloway, J Clarke - CBH – E Kostas and staff - GrainCorp – R Reid and staff
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- DAFF Qld – G Daglish, A Ridley, V Ooi, P Burrill, P Collins, D Schlipalius, A Tuck - UQ – G Walter, F Ahmad - QUT – S Raghu, M Whitehouse - NSW DPI – M Stevens, G Warren biosecurity built on science
 For more information, please email greg.daglish@daff.qld.gov.au
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