![Page 1: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/1.jpg)
Conserving natural enemy population in glasshouse crops
National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014
Gerben Messelink, Wageningen UR Greenhouse Horticulture
![Page 2: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/2.jpg)
Change
Drivers for change in crop protection:
Pesticide resistance of pests
ChangeChange
![Page 3: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/3.jpg)
Is biological control with natural enemies always working well?
![Page 4: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/4.jpg)
Nr 1 vegetables: aphids, Myzus persicae, Aulacortum solani
Problems: Natural enemies not effective enough and too expensive Problems with establishment of natural enemies (eg
predatory midges)
Nr 1 vegetables: aphids, Myzus persicae,
![Page 5: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/5.jpg)
Nr 2 vegetables: spider mites, Tetranychus urticae
Problems: Side-effects pesticides (e.g. neonicotinoids against
Feltiella) Poor quality Phytoseilius persimilis? Interaction with other predatory mites?
![Page 6: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/6.jpg)
Nr 3 vegetables: caterpillars, Chrysodeixis chalcites, Lacanobia oleracea etc.
Problems: Larval parasitoids not commercially available (too
expensive) Trichogramma not effective
![Page 7: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/7.jpg)
Nr 4 vegetables: true bugs, Lygus rugulipennis, Liocoris tripustulatus, Lygocoris pabulinus Problems: natural enemies against adults not available
![Page 8: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/8.jpg)
Nr 5 vegetables: Tomato russet mite, Aculops lycopersici
Problems: Predatory mites get entrapped by the type VI glandular
trichomes on tomato stems
![Page 9: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/9.jpg)
Nr 1 ornamentals: western flower thrips, Frankliniella occidentalis
Problems: Low thresholds for thrips densities Poor establishment of effective predators: predatory
mites and predatory bugs (lack of food, unsuitable habitat, side-effects pesticides)
Strong side-effects pesticides (e.g. meltatox in roses)
![Page 10: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/10.jpg)
Nr 2 ornamentals: mealybugs, Planococcus citri (and others..)
Problems: Parasitoids and Cryptolaemus montrouzieri often not
effective and too expensive
![Page 11: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/11.jpg)
Nr 3 ornamentals: armoured scales, Aulacaspis rosae, Diaspis boiduvalli
Problems: Natural enemies not available or not always effective. Side-effects other pesticides
![Page 12: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/12.jpg)
Nr 4 ornamentals: whiteflies, Trialeurodes vaporariorum, Bemisia tabaci
Problems: Natural enemies not effective at lower temperatures
(gerbera) Poor establishment of natural enemies (lack of food,
side-effects pesticides) Zero-tolerance policy (Poinsettia)
![Page 13: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/13.jpg)
Nr 5 ornamentals: Echinothrips americanus
Problems: Predatory mites not very effective Poor establishment of Orius bugs Effective mirid predators cause damage to flowers
(gerbera) Predatory thrips of lacewing larvae are too expensive
and not effective enough
![Page 14: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/14.jpg)
Summarizing: reasons limited use of biocontrol
Not only because of social aspects (attitude industry and government) or regulations but also because: Natural enemies are not effective enough Natural enemies do not establish well Natural enemies are too expensive Natural enemies are not available
![Page 15: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/15.jpg)
Enhancing efficacy of natural enemies
Enhancing quality of natural enemies: ● Better rearing methods ● Selective breeding (pesticide resistance, climate,
symbionts) ● olfactory conditioning
Enhancing establishment ● alternative food, prey, hosts ● oviposition sites or shelters ● Adapting the greenhouse climate/microclimate ● avoiding pesticide side-effects ● The right combinations of natural enemies
![Page 16: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/16.jpg)
crop and climate adapted natural
enemiesalternative food
habitat enrichment lure & retain
standing army
![Page 17: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/17.jpg)
Methods for conserving natural enemy populations: some examples
The right combinations of natural enemies Banker plants Insectary plants Food sprays Mulch layers
![Page 18: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/18.jpg)
A food web with 4 pest species and their natural enemies
![Page 19: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/19.jpg)
Aphidoletes aphidimyza larvae + eggs
Macrolophus pygmaeus nymph
Parasitoid mummies
Episyrphus balteatus egg
Aphidoletes aphidimyzaMacrolophus pygmaeus nymph
Are all these complexities realistic?
![Page 20: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/20.jpg)
Bad establishment caused by hyperpredation
![Page 21: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/21.jpg)
- Predatory mites + predatory mites
![Page 22: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/22.jpg)
Densities of aphids, midge eggs and midge larvae after 7 days
0
100
200
300
400
500
600
700
800
aphids gall midge eggs gall midge larvae
Den
sity
(num
ber/p
lant
)
without A. swirskiiwith A. swirskii
p = 0.007
p < 0.001
p < 0.001
Messelink et al., Biological Control 2011
![Page 23: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/23.jpg)
Banker plant: Castor bean Ricinus communis
Iphiseius degenerans
Amblyseius swirskii
Euseius ovalis
![Page 24: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/24.jpg)
Castor bean plant Ricinus communis
![Page 25: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/25.jpg)
Banker plants for Aphid parasitoids
Most popular: combination of winter wheat & Sitobion avenae for production of Aphelinus abdominalis or Aphidius ervi
● Advantages: cheap rearing of parasitoids, “fresh” parasitoids
● Disadvantages: smaller wasps than on host from mass production, increased risk on hyperparasitism
Huang et al., Critical Reviews in Plant Sciences 2011
![Page 26: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/26.jpg)
Dominant hyperparasitoid: Dendrocerus aphidum
Related to another common species: Dendrocerus carpenteri Parasitizes parasitized aphids 4-10 days after parasitism by the
primary parasitoids Generalist species: most aphid-parasitoid combinations are
vulnerable
![Page 27: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/27.jpg)
Conservation of Aphidoletes aphidimyza
The banker plant method, similar to the parasitoids: combination of winter wheat & Sitobion avenae
Intercropping with kohlrabi (with cabbage aphids)
![Page 28: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/28.jpg)
Banker planmts for Orius
![Page 29: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/29.jpg)
Possible candidates for Orius laevigatus in ornamentals
Amaranthus cruentes (red amaranthus) Ornamental pepper: Capsicum ‘Black Pearl’ Corn flower, Centaurea cyanus Strawberry + strawberry whitefly, Aleyrodes lonicerae
(not for roses)
![Page 30: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/30.jpg)
Insectary plants for nectar fuelling:
conservation of Episyrphus balteatus
Alyssum lobularia
![Page 31: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/31.jpg)
Insectary plants for nectar fuelling:
conservation of Episyrphus balteatus
Buckwheat, Fagopyrum esculentum
![Page 32: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/32.jpg)
Conservation of Episyrphus balteatus
Nectar fuelling with insectary plants
balteatus
Crambe hispanica
![Page 33: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/33.jpg)
Alternative food sources for the mirid predator Macrolophus pygmaeus
0
50
100
150
200
250
untreated(no food)
greenhousewhitefly
Ephestiaeggs
maize pollen Predfeed® Artemiacysts
Pro
du
ced
off
spri
ng
per
10
co
up
les
pygmaeus
![Page 34: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/34.jpg)
Applying alternative food in practice
![Page 35: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/35.jpg)
Applying alternative food in practice
0
20
40
60
80
100
120
Petit Sweet PommoDolce
Petit Sweet PommoDolce
Petit Sweet PommoDolce
Ephestia eggs Artemia cysts untreated (no food)
Den
sity
of
M. p
ygm
aeus
/pla
nt week 5
week 8
week 11
week 14
Weekly application: Ephestia eggs: 35 g/ha (€800/kg) Artemia: 135 g/ha (€20/kg)
![Page 36: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/36.jpg)
Food and shelter for predatory mites
![Page 37: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/37.jpg)
Alternative food for predatory mites
0
0.5
1
1.5
2
2.5
cattail pollen corn pollen Ephestia eggs Artmia cysts
Ovi
po
siti
on
rat
e
day 2
day 3
a
abAA
c
b
B
A
![Page 38: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/38.jpg)
Effects of food on thrips
0
2
4
6
8
10
12
14
16
18
20
0 3 6 9 12 15
Ovi
po
siti
on
rat
e
Time (days)
no added food
cattail pollen
corn pollen
Ephestia eggs
Artemia cystsa
b
b
a
a
![Page 39: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/39.jpg)
Effects of food on thrips predation
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
day 2 day 3
Pre
dat
ion
rat
e
thrips
thrips + pollen
*
![Page 40: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/40.jpg)
Effects on biological control of thrips
![Page 41: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/41.jpg)
Effects on biological control of thrips
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 1 2 3 4 5 6 7 8 9
Pre
dat
or
den
siti
es
Time (weeks)
thrips
thrips + cattail pollen
thrips + corn pollen
thrips + Ephestia eggs
a
c
b
ab
![Page 42: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/42.jpg)
Effects on biological control of thrips
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 1 2 3 4 5 6 7 8 9
Thri
ps
den
siti
es
Time (weeks)
untreated
A. swirskiicattail pollen
corn pollen
Ephestia eggs
a
ab
c
bc
abc
![Page 43: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/43.jpg)
Mulch layers for enhancing pest control
![Page 44: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/44.jpg)
mulch-layer composition
Prey mite population increase
9 mulch-layers
2 prey-mites:
● Acarus siro
● Carpoglyphus lactis
![Page 45: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/45.jpg)
0 10,000 20,000
Soil
Bark
Yeast
Biotop®
Biotop® + yeast
Bran
Bran + yeast
Bran + oats
Wheat
Barely
Mite density (number / 100 ml substrate)
C. lactis
A. siro
0 10,000 20,000 30,000 40,000
Week 4Week 2
![Page 46: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/46.jpg)
mulch layers in Alstroemeria
![Page 47: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/47.jpg)
![Page 48: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/48.jpg)
Effect on thrips and predatory mites (N. cucumeris)
0
2
4
6
8
10
12
0%
20%
40%
60%
80%
100%
2 4 6 8
- Top-layerThrips
Predatory mites
0
2
4
6
8
10
12
0%
20%
40%
60%
80%
100%
2 4 6 8
Pred
ator
y m
ites
(# /
m s
tem
)
Thrip
s(%
infe
cted
ste
ms)
Weeks after introduction
+ Top-layer
![Page 49: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/49.jpg)
Conclusions
- Mulch layer: ● Predatory mites do not establish on crop
● Pest pressure increases gradually
+ mulch layer: ● Increase in pest-pressure is followed by strong increase in predatory
mite density on crop
● Pest pressure decreases
Better predatory mite establishment and thrips-control due to mulch layer application
![Page 50: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/50.jpg)
Open rearing units in
cut-roses
![Page 51: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/51.jpg)
Effect on predatory mites (A. swirskii)
0
2
4
6
8
0 2 4 6 8
Pred
ator
y m
ites (
num
ber/l
eaf)
Time (weeks after introduction)
- Top-layer
+ Top-layer
• Strong increase in predator density due to mulch layer application
• Increased predation rates in treatments with rearing units
![Page 52: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/52.jpg)
conclusions
Establishment of natural enemies can be enhanced with banker plants, insectary plants, food sprays and mulch layers
Be aware of food web complexities through presence of hyperparasitoids and hyperpredators
Be aware of short-term dynamics when the alternative food is also edible for the pest species
![Page 53: Conserving natural enemy population in glasshouse crops · glasshouse crops National Protected Crops Conference & Trade Show 2014 Teagasc, Ashtown, Dublin, October 21, 2014 Gerben](https://reader033.vdocuments.us/reader033/viewer/2022052022/6037d7e160123d245a7a55d0/html5/thumbnails/53.jpg)
Thanks for your attention!