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Biological and Microbial Control Options for Managing Lygus Bug in Strawberries
Surendra DaraStrawberry and Vegetable Crops Advisor and Affiliated IPM Advisor
University of California Cooperative ExtensionSanta Barbara and San Luis Obispo Counties
[email protected] @calstrawberries @calveggies
Lygus Bug IPM Seminar, UCCE, Watsonville, 18 April, 2013
Current pest management practices• Chemical pesticides and to a limited extent insecticidal soaps,
oils, pyrethrin, spinosad, and Bt• Release of predatory mites• No major emphasis on biological control of lygus bug
Acres treated with insecticides in strawberries
Pesticide Use Report Data 2010, CDPR
Insecticide 2006 2007 2008 2009 2010Acres treated with different insecticides
Oil 690 7,408 20,204 36,957 53,860
Novaluron (Rimon) 24,497 41,149
Fenpyroximate (Akari) 41,149
Sulfur 129,069 139,486 134,076 146,790 157,125
Naled (Dibrom) 18,681 23,819 33,916 51,937 44,587
Spiromesifen (Oberon) 10,375 16,225 18,439 22,485 29,404
Fenpropathrin (Danitol) 20,217 21,272 25,688 27,885 21,229
Abamectin (Agri‐Mek) 13,024 16,962 26,103 29,751 35,876
Total 191,366 217,764 238,222 278,848 288,221
Acreage in California 29,187 29,937 31,169 35,915 34,426
Total amount of pesticides in pounds (fungicides, insecticides, and herbicides used)
9,394,745 9,669,764 9,918,143 10,041,462 10,972,995
Pesticide use in California strawberries‐2009
Pesticide Action Network North Americahttp://www.pesticideinfo.org/DS.jsp?sk=1016
Chemical name Chemical class Trade name Gross pounds Acres treatedBifenazate Unclassified Acramite, Floramite 17,353 35,480Bifenthrin Pyrethroid Brigade 4,485 41,235Chlorpyrifos Organophosphorus Lorsban 11,323 11,384Fenpropathrin Pyrethroid Danitol 9,243 27,783Malathion Organophosphorus Malathion 144,417 76,208Methomyl N‐methyl carbamate Lannate 6,104 7,641Naled Organophosphorus Dibrom 48,723 51,689Spiromesifen Keto‐enol Oberon 5,338 22,477Total 246,986 273,897
Biocontrol agents and basics
• Multiple natural enemies for different life stages of pest• Conserving natural enemies• Providing refuge for natural enemies• Using chemicals that are less disruptive to natural enemies
Lygus adult killed by Beauveria bassianaNymphal parasitoid, Peristenus stygicus
www.state.nj.us
Egg parasitoid, Anaphes iole
0
10
20
30
40
50
Nymphs Adults
Seasonal occurrence of lygus bugConventional strawberry field
Treatment threshold 1 nymph
Danitol
Dibrom
& Rim
on
Danitol Brigade & Rim
on
Malathion
Dibrom
Dibrom
Dibrom
& Rim
on
Malathion
& Rim
on
No. of Lygus per 20 strawbe
rry plan
ts
0
10
20
30
40
50
Nymphs Adults
Seasonal occurrence of lygus bugOrganic strawberry field
No. of Lygus per 20 strawbe
rry plan
ts
Treatment threshold
Generalist Predator Gut Content Analyses Lygus bug predation rates of field‐collected predators (via PCR)*
Big‐eyed bug (N = 84)% preyed upon lygus bugs: 13%
Minute pirate bug (N = 286)% preyed upon lygus bugs: 14%
Damsel bug (N = 108)% preyed upon lygus bugs: 20%
Crab spider (N = 89)% preyed upon lygus bugs: 26%
*preliminary data
J. Hagler, D. Nieto, S. Swezey, S. Machtley and J. Bryer
a missing data for parasitism in 2004
Fig. 1. Seasonal trends in Lygus densities and proportion parasitized by P. relictus. Wild vegetation release sites, Castro1 and Harkins Slough. Averagedover July, August, and September.
2002 2004 2006 2008 2010 2012
ME
AN N
YMP
HS
PE
R S
WE
EP
AN
D S
EM
0.0
0.2
0.4
0.6
0.8
1.0
1.2
PAR
ASIT
ISM
AN
D S
EM
0.0
0.2
0.4
0.6
0.8
1.0
density nymphs parasitism
a
Castro1
first re
lease
YEAR OF SAMPLING2003 2004 2005 2006 2007 2008 2009 2010 2011
MEA
N NY
MPS
PER
SW
EEP
AND
SEM
0
1
2
3
4
5
PARA
SITI
SM A
ND S
EM
0.0
0.2
0.4
0.6
0.8
1.0density nymphs parasitism
Harkins Slough
first r
eleas
e
Photo by Charles Pickett
Parasitism of lygus bug nymphs by the introduced parasitoid Peristenus relictus
C. Pickett, S. Swezey, D. Nieto and J. Bryer
Alfalfa Trap Crops and Yield (2012)*
0
1
2
3
4
5
6
7
8
berries with TC berries without TC
mean % dam
age
3.63.73.83.94
4.14.24.34.44.54.6
berries with TC berries without TC
mean # un
damaged
berrie
s/plant
Field data from 2012 organic strawberries in rows 1‐4, 7‐10, 13‐16 and 19‐22 adjacent to an alfalfa trap crop (TC) and control row of strawberries
D. Nieto, S. Swezey and J. Bryer
*preliminary data
Potential of entomopathogens• Entomopathogens like Beauveria bassiana, Metarhizium
anisopliae, and Isaria fumosorosea are pathogenic to most of the strawberry pests
http://archimede.bibl.ulaval.ca/archimede/fichiers/22512/ch01.htmlhttp://www.plant‐health.co.za/eco‐bb.html
Lygus
Spider mites
Thrips
Whitefly
Potential of entomopathogens
Entomopathogens Environment
Hosts
Min: 38‐70 oFMax: 64‐83oFAvg: 50‐70oF
Possible microbial control strategy• Incorporating microbial control into IPM• Foliar application – alone and along with chemical pesticides
• Endophytic colonization of the strawberry plants
Impact on strawberry IPM• Reduces the chemical pesticide use• Reduces the risk of pesticide resistance• Extends the life of effective chemicals• Improves the pest management• Enhances the efficacy of IPM
•Objectives•Improve the efficacy of B. bassiana•Reduce the usage of chemicals
•Treatments•0.19 lb/ac or 1X107 conidia/ml of BotaniGard 22 WP (label rate 1/2‐2 lb/acre)•1/5 the label rate of Actara (1 pt/ac), Aza‐Direct (2 qrt/ac), Danitol (11 oz/ac) and Dibrom (1 pt/ac)
Chemicals and B. bassiana against Lygus
Chemicals and B. bassiana against Lygus
0
20
40
60
80
100
1 2 3 4 5
ControlActaraAza‐DirectBotaniGard 22 WPDanitolDibromActara+BotaniGardAza‐Direct+BotaniGardDanitol+BotaniGardDibrom+BotaniGard
Days after treatment
Cumulative mortality (%
)
Endophytic colonization
•Objectives•What is an ideal method of inoculation?•Does the fungus colonize strawberry plants?•If it does, how long does it persist in the plant?•Does the colonized fungus protect the plantfrom herbivore damage?
Endophytic colonization‐B. bassiana•Rinsed, surface‐sterilized and rinsed the plant material•Plated plant tissue on selective medium•Plated rinsate on medium to verify contamination
Endophytic colonization‐B. bassiana
Emergence of colonized B. bassiana from treated plant tissue
No B. bassiana detected in controls
Roots Petioles Leaves
Endophytic colonization‐M. anisopliaeM. anisopliae‐treated plants
Untreated control plants
10 DAT: 59% plants damaged14 DAT: 65% plants damaged
10 DAT: 44% plants damaged14 DAT: 56% plants damaged
Small plot field trial‐2010
0
0.2
0.4
0.6
0.8
1
8/16/2010 8/25/2010 8/27/2010 9/2/2010 9/8/2010 9/10/2010 9/16/2010
Average nu
mbe
r per plant
Days before or after treatment
1‐3 instar nymphs 4‐5 instar nymphs Adults
On flowering hostsTreatments1st – 8/202nd – 8/273rd – 9/24th – 9/9
Large field trial‐2012
Treatments:1. Untreated control2. Assail 70 WP (acetamiprid) 3 oz/ac in 50 gal3. BotaniGard WP (Beauveria bassiana) 2lb/ac in 50 gal4. BotaniGard WP 2lb/ac + Molt‐X (azadirachtin) 8 fl oz/ac in 50 gal5. BotaniGard WP 2lb/ac + Danitol (fenpropathrin) ½ label rate 5.3 fl oz/ac in 50 gal6. BotaniGard WP 2lb/ac + Assail ½ label rate 1.5 oz/ac in 50 gal7. AzaGuard (azadirachtin) 8 fl oz/ac in 50 gal8. AzaGuard 16 fl oz/ac in 50 gal9. Rimon 0.83 EC (novaluran) 12 fl oz/ac + Brigade (bifenthrin) 16 oz/ac in 50 gal
Experimental period: July‐August, 2012
Large field trial‐2012Lygus populations following each spray application
Num
ber o
f lygus bugs/20
plants
0
5
10
15
Untreated Acetamiprid Novaluron +Bifenthrin
B. bassiana Bb +Azadirachtin
Bb + 1/2Fenpropathrin
Bb + 1/2Acetamiprid
Azadirachtin(8 fl oz)
Azadirachtin(16 fl oz)
Pre‐treatment I Spray II Spray III Spray
Large field trial‐2012Lygus populations before and after treatment
Num
ber o
f lygus bugs/20
plants
0
5
10
15
Untreated Acetamiprid Novaluron +Bifenthrin
B. bassiana Bb +Azadirachtin
Bb + 1/2Fenpropathrin
Bb + 1/2Acetamiprid
Azadirachtin(8 fl oz)
Azadirachtin(16 fl oz)
Pre‐treatment Post‐treatment
Miticide trial 2012 – Mobile predatory mites
0
2
4
60 DAT 3 DAT
Num
ber o
f preda
tory m
ites/leaflet
Nymphs and Adults‐Neoseiulus spp.
Conclusions•Conserve biocontrol agents to exploit their potential•Microbial and botanical solutions have a good potential in strawberry IPM•B. bassiana+ ½ acetamiprid, B. bassiana+azadirachtin, and azadirachtin did fairly well compared to chemicals for lyguscontrol•Consider combinations of reduced rates of chemicals and other options for good IPM
Compatibility of B. bassiana and fungicidesLab assay with mealworms (Tenebrio molitor), B. bassiana, and some common strawberry fungicides
Compatibility of B. bassiana and fungicides
Average of 6 assays
0
20
40
60
80
100
Dead Infected
bc
a
cd
e
ab
cd
a
de
cd
Mean pe
rcen
t mortality/infection
bc
a
ded
ab
cd
a
de
c
Conclusions
• Elevate and Quintec are compatible with B. bassiana• B. bassiana was not affected by Pristine when applied after one day.
• Other fungicides may be compatible with appropriate time intervals.