M. Molefe - Phenology of thrips species - Damage assessment - Premature nut drop - Maturity of abscised nuts - Cultivar susceptibility - Predatory mites & natural enemies - Economic loss assessment - IPM programme development Thank you for your support! Any questions?

1. Towards Understanding the Economic Impact
of Thrips in South Africa: Preliminary Findings
Colleen Hepburn¹, Michael Stiller² & Martin Villet¹
¹Department of Zoology & Entomology, Rhodes University, Grahamstown, South Africa
²Agricultural Research Council - Plant Protection Research Institute, National Collection of
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Insects: Biosystematics, Roodeplaat, Pretoria, South Africa

2. Aims and objectives:
• Thrips complex - identify and
assign to guilds (damaging /
predatory / beneficial).
• Phenology of thrips causing
damage.
• Develop practical monitoring
and scouting strategies.
• Ascertain damage to flush,
blossoms, nut-set, small &
mature nuts.
• Determine % premature nut
drop and abscission
attributed to thrips.
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3. Aims and objectives:
• Does thrips damage affect pre- and
post-zygotic development of nut?
• Does cosmetic damage (bronzing)
affect photosynthesis and / or
kernel characteristics (size / weight
/ oil content)?
• Are some cultivars more
susceptible to thrips damage?
• Begin working on IPM programme
which is ecologically sound.
• Determine % economic loss of
yield.
• Thrips complex distribution in
macadamia-growing areas. Photos: Michael Stiller, ARC-PPRI (2012)
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4. Order: Thrips (Thysanoptera)
• 2 suborders – Terebrantia and Tubulifera
• 9 families
• 750 genera
• 8000 extant species (> 5500 described)
50% - feed on fungi
40% - feed on dicotyledonous plants
(i.e. grasses)
9% - predatory or feed on mosses,
gymnosperms or cycads
1% - identified as serious pests
(+ transmission of viruses)
4

5. Average Thrips Life Cycle
(2½ - 4 days)
(1 - 2 days)
(Longevity
30 - 45 days (2 - 4 days)
150 - 300 (Immature stages = max.
eggs)
15 days)
(1 - 2 days)
(1 - 3 days)
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6. Field work (over 33 weeks) - sampling
protocol
• 13 cultivar sites
• 5 data trees in each
cultivar site (n = 65)
• 20 racemes / growth
points on each tree
sampled weekly
(n = 1300)
In total n = 42900
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7. Study sites (13) and variety of cultivars
LOCALITY CULTIVAR AGE TREATED
ARC-ITSC Nelmak D Orchard Nelmak D 8 yrs No
ARC-ITSC Variety Orchard Beaumont 13 Yrs No
ARC-ITSC Variety Orchard Nelmak 2 13 Yrs No
ARC-ITSC Variety Orchard 788 13 Yrs No
ARC-ITSC Variety Orchard A4 13 Yrs No
ARC-ITSC Variety Orchard 816 13 Yrs No
ARC-ITSC Variety Orchard A16 13 Yrs No
ARC Friedenheim Farm Beaumont 6 yrs Yes
Commercial Farm 788 4 yrs Yes
Commercial Farm Nelmak D 6 yrs Yes
Commercial Farm 816 4 yrs Yes
Commercial Farm Beaumont 12 yrs Yes
Commercial Farm Nelmak D 12 yrs Yes
7

8. 20 growth points per tree (i.e. new
flush, blossoms, nut set, small
nuts, mature nuts) sampled weekly
8

9. Photos representing raceme developmental stages
and abscised nuts for each site were taken weekly
(phenology)
9

10. During the last 7 weeks of sampling, abscised nuts
with and without thrips damage + 20 random nut
sample from trees were tested for maturity (i.e.
dehusked, dried, cracked & floated)
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11. AVERAGE # OF THRIPS COLLECTED FROM DATA TREES AT
ALL 13 SITES OVER THE 33 WEEK PERIOD
900 30
850
800
750 25
AVERAGE # THRIPS FROM ALL SITES
WEEKLY AVERAGE TEMPERATURE °C
700
650 ARC NELMAK D 8YRS
600 ARC VARIETY ORCHARD BEAUMONT 13YRS 20
ARC VARIETY ORCHARD NELMAK 2 13YRS
550
ARC VARIETY ORCHARD 788 13YRS
500
ARC VARIETY ORCHARD A4 13YRS
450 ARC VARIETY ORCHARD 816 13YRS 15
400 ARC VARIETY ORCHARD A16 13YRS
ARC FRIEDENHEIM BEAUMONT 6YRS
350
COMMERCIAL FARM 788 4YRS
300 10
COMMERCIAL FARM NELMAK D 6YRS
250 COMMERCIAL FARM 816 4YRS
200 COMMERCIAL FARM BEAUMONT 12YRS
COMMERCIAL FARM NELMAK D 12YRS
150 5
AVERAGE TEMPERATURE (°C)
100
50
0 0
WEEKS 11

12. COMMERCIAL FARM SPRAY DATES: BEAUMONT
(12 yrs) & NELMAK D (12 yrs) SITES [N.B. Sprays based on
weekly scouting records]
300 30
250 25
WEEKLY AVERAGE TEMPERATURE °C
COMMERCIAL FARM BEAUMONT 12YRS
200 20
COMMERCIAL FARM NELMAK D 12YRS
AVERAGE TEMPERATURE (°C)
AVERAGE # THRIPS
150 15
Cypermethrin Cypermethrin
Acephate Cypermethrin Cypermethrin
100 10
50 5
0 0
WEEKS 12

13. Defining thrips damage:
Only green, shiny nuts on
tree and green abscised
nuts as at 11 November
2011
13

14. Two weeks later (26 November 2011), there
was a change in colour of some of the nuts
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15. Abscised nuts: different types of husk damage
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16. TOTAL # ABSCISED NUTS OVER 33 WEEK
SAMPLING PERIOD
4200 30
4000
3800
3600
25
3400
3200
WEEKLY AVERAGE TEMPERATURE
3000 ARC NEL D 8YRS
ARC VAR ORCH B'MONT 13YRS
2800 20
TOTAL # ABSCISED NUTS
ARC VAR ORCH NEL 2 13YRS
2600
ARC VAR ORCH 788 13YRS
2400
ARC VAR ORCH A4 13YRS
2200
ARC VAR ORCH 816 13YRS 15
2000 ARC VAR ORCH A16 13YRS
1800 ARC F'HEIM B'MONT 6YRS
1600 COMM FARM 788 4YRS
1400 COMM FARM NEL D 6YRS 10
1200 COMM FARM 816 4YRS
COMM FARM B'MONT 12YRS
1000
COMM FARM NEL D 12YRS
800
AVERAGE TEMPERATURE (°C) 5
600
400
200
0 0
WEEKS
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17. AVERAGE NUMBER OF ABSCISED NUTS SHOWN BY
STUDY SITE IN DESCENDING ORDER
AVERAGE #
RATING STUDY SITE ABSCISED
NUTS
1. Commercial Farm Beaumont 12 Yrs 391
2. Commercial Farm Nelmak D 12 Yrs 222
3. Commercial Farm 816 4 Yrs 170
4. ARC Variety Orchard Nelmak 2 13 Yrs 139
5. ARC Variety Orchard A16 13 Yrs 135
6. ARC Variety Orchard A4 13 Yrs 94
7. ARC Variety Orchard 816 13 Yrs 93
8. ARC Nelmak D Orchard 8 Yrs 62
9. ARC Variety Orchard 788 13 Yrs 61
10. Commercial Farm Nelmak D 6 Yrs 54
11. ARC Variety Orchard Beaumont 13 Yrs 53
12. Commercial Farm 788 4 Yrs 44
13. ARC Friedenheim Farm Beaumont 6 Yrs 25
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18. TOTAL # ABSCISED NUTS WITH THRIPS DAMAGE
OVER TIME.
1200 30
1000 25
TOTAL # NUTS WITH THRIPS DAMAGE
WEEKLY AVERAGE TEMPERATURE °C
ARC NEL D 6YRS
ARC VAR ORCH B'MONT 13YRS
800 20
ARC VAR ORCH NEL 2 13YRS
ARC VAR ORCH 788 13YRS
ARC VAR ORCH A4 13YRS
600 ARC VAR ORCH 816 13YRS 15
ARC VAR ORCH A16 13YRS
ARC F'HEIM B'MONT 6YRS
COMM FARM 788 4YRS
400 COMM FARM NEL D 6YRS
10
COMM FARM 816 4YRS
COMM FARM B'MONT 12YRS
COMM FARM NEL D 12YRS
200 5
WEEKLY AVERAGE TEMPERATURE (°C)
0 0
WEEKS 18

19. AVERAGE # ABSCISED NUTS WITH AND WITHOUT
THRIPS DAMAGE – ALL SITES
700 30
650
600
25
550
WEEKLY AVERAGE TEMPERATURE °C
AVE # ABSCISED NUTS
500
AVERAGE # ABSCISED NUTS
AVE # ABSCISED NUTS NO THRIPS DAMAGE
20
450 AVE # ABSCISED NUTS WITH THRIPS DAMAGE
400 AVERAGE TEMPERATURE (°C)
350 15
300
250
10
200
150
5
100
50
0 0
WEEKS 19

20. ARC NELMAK D: MATURITY COMPARISON OF
ABSCISED NUTS WITH AND WITHOUT THRIPS
DAMAGE
200 200
# NUTS ABSCISED # NUTS ABSCISED
180 # NUTS (Thrips dam) 180 # NUTS (No thrips dam)
# MATURE (Thrips dam) # MATURE (No thrips dam)
160 160
140 140
120 120
100 100
80 80
60 60
40 40
20 20
0 0
WEEKS WEEKS
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21. ARC VARIETY ORCHARD 816: MATURITY COMPARISON OF
ABSCISED NUTS WITH AND WITHOUT THRIPS DAMAGE
90 90
# NUTS ABSCISED # NUTS ABSCISED
80 # NUTS (Thrips dam) 80 # NUTS (No thrips dam)
# MATURE (Thrips dam) # MATURE (No thrips dam)
70 70
60 60
# NUTS
50 50
# NUTS
40 40
30 30
20 20
10 10
0 0
WEEKS WEEKS
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22. ARC VARIETY ORCHARD A16: MATURITY COMPARISON OF
ABSCISED NUTS WITH AND WITHOUT THRIPS DAMAGE
320 320
300 # NUTS ABSCISED 300 # NUTS ABSCISED
280 # NUTS (Thrips dam) 280 # NUTS (No thrips dam)
# MATURE (Thrips dam) 260 # MATURE (No thrips dam)
260
240 240
220 220
200 200
# NUTS
# NUTS
180 180
160 160
140 140
120 120
100 100
80 80
60 60
40 40
20 20
0 0
WEEKS WEEKS 22

23. ARC NELMAK D: Photos of damage to nuts with thrips
damage, without thrips damage and 20 nut sample
tested for oil content and maturity (N.B. Stinkbug damage)
a b c
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24. Identification
During the 2011-2012 season a
total of 44 062 specimens
collected and counted
A number of morphological
characters are used to identify to
species (i.e. setae, surface
sculpture, detail on antennae,
wing venation and setation)
Adults 1.0 – 1.6 mm long
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25. Some of the thrips species being identified by
Michael Stiller, ARC-PPRI National Collection of Insects:
Biosystematics, Pretoria, South Africa
So far no S. aurantii (citrus) or
Heliothrips haemorrhoidalis
(greenhouse)
Thrips gowdeyi (Bagnall)
Thrips tenellus Trybom
Thrips pusillus Bagnall
Taeniothrips sp.
Scirtothrips ?combreti Fauré
Megalurothrips sjostedti
Trybom
Hercinothrips sp.
Helionothrips sp.
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26. Identification/Photos: Michael Stiller, ARC-PPRI Biosystematics, Pretoria, SA
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27. Species of mites identified by
Eddie Ueckermann, ARC-PPRI National
Collection of Insects: Biosystematics,
Pretoria, South Africa
Hexibdella sp. (Bdellidae)
ALL PREDATORY MITES Snout Mite
Photo: Tom Murray
Phytoseiidae Amblyseius herbicolus
Typhlodromus (Anthoseius) vescus
Typhlodromus (Anthoseius) celastrus
Neoseiulus barkeri
Bdellidae Hexibdella sp. near singula Anystis baccarum (Anystidae)
Whirligig mite
Photo: BugGuide.net
Anystidae Anystis baccarum
Stigmaeidae Agistemus africanus
Tetranychidae Eutetranychus sp.
Mononychellus nr, heteromniae
Agistemus africanus (Stigmaeidae)
So far no broad mite or citrus mites Red Velvet Mite
Photo: Edublogs.org
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28. Aims & Objectives: 2012-2013 Season
13 July 2012: Set up study sites and
began scouting and monitoring.
Continuing with identification of thrips
species and sorting into guilds,
incorporated temperature and rainfall in
data, working out phenology of
macadamia cultivars from photo data.
Aug: Soil application of Metarhizium
(entomopathogenic fungi) at some of
the sites.
Field collections: thrips complex
distribution of thrips in macadamia Photo Source: Wikipedia.org
growing areas of South Africa. Metarhizium on cockroach
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29. Acknowledgements:
SAMAC (Research Project Funding 2011-2012, 2012-2013)
Rhodes University, Grahamstown, South Africa
(Scholarship 2011)
National Research Foundation, Pretoria, South Africa
(Scholarship 2012-2014)
Ernst & Ethel Eriksen Trust, Bryanston, South Africa
(Scholarship 2011 & 2012)
Mr Johannes Ngomane, Dr Schalk Schoeman, Prof Randall
Hepburn, Dr Eddie Ueckermann, Messrs Gerhard Nortjé,
Andrew Sheard, Alwyn du Preez and Len Hobson
Subtrop, Tzaneen, and ARC-ITSC, Nelspruit, South Africa
ERNST AND ETHEL ERIKSEN TRUST
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