Biological and Microbial Control Options for Managing Lygus Bug in Strawberries Surendra Dara Strawberry and Vegetable Crops Advisor and Affiliated IPM Advisor University of California Cooperative Extension Santa Barbara and San Luis Obispo Counties skdara@ucdavis.edu strawberriesvegetables @calstrawberries @calveggies Lygus Bug IPM Seminar, UCCE, Watsonville, 18 April, 2013
Lygus bug Lygus bug Lygus bug first instar next to aphid, 4 th and 5 th instars, and adult
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 Insecticide 2006 2007 2008 2009 2010 Acres 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 Report Data 2010, CDPR
Pesticide use in California strawberries 2009 Chemical name Chemical class Trade name Gross pounds Acres treated Bifenazate Unclassified Acramite, Floramite 17,353 35,480 Bifenthrin Pyrethroid Brigade 4,485 41,235 Chlorpyrifos Organophosphorus Lorsban 11,323 11,384 Fenpropathrin Pyrethroid Danitol 9,243 27,783 Malathion Organophosphorus Malathion 144,417 76,208 Methomyl N methyl carbamate Lannate 6,104 7,641 Naled Organophosphorus Dibrom 48,723 51,689 Spiromesifen Keto enol Oberon 5,338 22,477 Total 246,986 273,897 Pesticide Action Network North America http://www.pesticideinfo.org/ds.jsp?sk=1016
Biocontrol agents and basics www.state.nj.us Egg parasitoid, Anaphes iole Nymphal parasitoid, Peristenus stygicus Lygus adult killed by Beauveria bassiana 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
Seasonal occurrence of lygus bug Conventional strawberry field 50 40 30 20 10 0 Nymphs Adults Treatment threshold 1 nymph No. of Lygus per 20 strawberry plants Danitol Dibrom & Rimon Dibrom Danitol Dibrom & Rimon Brigade & Rimon Malathion & Rimon Malathion Dibrom
Seasonal occurrence of lygus bug Organic strawberry field No. of Lygus per 20 strawberry plants 50 40 30 20 10 0 Nymphs Adults Treatment threshold
Generalist Predator Gut Content Analyses Lygus bug predation rates of field collected predators (via PCR)* J. Hagler, D. Nieto, S. Swezey, S. Machtley and J. Bryer 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
Fig. 1. Seasonal trends in Lygus densities and proportion parasitized by P. relictus. Wild vegetation release sites, Castro1 and Harkins Slough. Averaged over July, August, and September. Parasitism of lygus bug nymphs by the introduced parasitoid Peristenus relictus C. Pickett, S. Swezey, D. Nieto and J. Bryer MEAN NYMPHS PER SWEEP AND SEM 1.2 1.0 0.8 0.6 0.4 0.2 0.0 first release a Castro1 density nymphs parasitism 2002 2004 2006 2008 2010 2012 1.0 0.8 0.6 0.4 0.2 0.0 PARASITISM AND SEM a missing data for parasitism in 2004 Photo by Charles Pickett MEAN NYMPS PER SWEEP AND SEM 5 4 3 2 1 0 first release Harkins Slough density nymphs parasitism 2003 2004 2005 2006 2007 2008 2009 2010 2011 1.0 0.8 0.6 0.4 0.2 0.0 PARASITISM AND SEM YEAR OF SAMPLING
Alfalfa Trap Crops and Yield (2012)* D. Nieto, S. Swezey and J. Bryer 8 7 6 mean % damage 5 4 3 2 mean # undamaged berries/plant 1 0 4.6 4.5 4.4 4.3 4.2 4.1 4 3.9 3.8 3.7 3.6 berries with TC berries with TC berries without TC berries without TC *preliminary data 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
Potential of entomopathogens Entomopathogens like Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea are pathogenic to most of the strawberry pests Lygus Spider mites Thrips Whitefly http://www.plant health.co.za/eco bb.html http://archimede.bibl.ulaval.ca/archimede/ fichiers/22512/ch01.html
How entomopathogenic fungi infect insects
Potential of entomopathogens Hosts Min: 38 70 o F Max: 64 83 o F Avg: 50 70 o F Entomopathogens Environment
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
Chemicals and B. bassiana against Lygus Objectives Improve the efficacy of B. bassiana Reduce the usage of chemicals Treatments 0.19 lb/ac or 1X10 7 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
Chemicals and B. bassiana against Lygus 100 Cumulative mortality (%) 80 60 40 20 0 1 2 3 4 5 Days after treatment Control Actara Aza Direct BotaniGard 22 WP Danitol Dibrom Actara+BotaniGard Aza Direct+BotaniGard Danitol+BotaniGard Dibrom+BotaniGard
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 plant from 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 Roots Petioles Emergence of colonized B. bassiana from treated plant tissue No B. bassiana detected in controls Leaves
Endophytic colonization B. bassiana Root Petiole Leaf lamina
Endophytic colonization M. anisopliae M. anisopliae treated plants 10 DAT: 44% plants damaged 14 DAT: 56% plants damaged 10 DAT: 59% plants damaged 14 DAT: 65% plants damaged Untreated control plants
Small plot field trial 2010 Treatments 1 st 8/20 2 nd 8/27 3 rd 9/2 4 th 9/9 Average number per plant 1 0.8 0.6 0.4 0.2 On flowering hosts 1 3 instar nymphs 4 5 instar nymphs Adults 0 8/16/2010 8/25/2010 8/27/2010 9/2/2010 9/8/2010 9/10/2010 9/16/2010 Days before or after treatment
Large field trial 2012 Treatments: 1. Untreated control 2. Assail 70 WP (acetamiprid) 3 oz/ac in 50 gal 3. BotaniGard WP (Beauveria bassiana) 2lb/ac in 50 gal 4. BotaniGard WP 2lb/ac + Molt X (azadirachtin) 8 fl oz/ac in 50 gal 5. BotaniGard WP 2lb/ac + Danitol (fenpropathrin) ½ label rate 5.3 fl oz/ac in 50 gal 6. BotaniGard WP 2lb/ac + Assail ½ label rate 1.5 oz/ac in 50 gal 7. AzaGuard (azadirachtin) 8 fl oz/ac in 50 gal 8. AzaGuard 16 fl oz/ac in 50 gal 9. 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 2012 15 Lygus populations following each spray application Pre treatment I Spray II Spray III Spray Number of lygus bugs/20 plants 10 5 0 Untreated Acetamiprid Novaluron + Bifenthrin B. bassiana Bb + Azadirachtin Bb + 1/2 Fenpropathrin Bb + 1/2 Acetamiprid Azadirachtin (8 fl oz) Azadirachtin (16 fl oz)
Large field trial 2012 Lygus populations before and after treatment Pre treatment Post treatment 15 Number of lygus bugs/20 plants 10 5 0 Untreated Acetamiprid Novaluron + Bifenthrin B. bassiana Bb + Azadirachtin Bb + 1/2 Fenpropathrin Bb + 1/2 Acetamiprid Azadirachtin (8 fl oz) Azadirachtin (16 fl oz)
Miticide trial 2012 Mobile predatory mites Number of predatory mites/leaflet 0 DAT 3 DAT 6 4 2 0 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 lygus control Consider combinations of reduced rates of chemicals and other options for good IPM
Compatibility of B. bassiana and fungicides Lab assay with mealworms (Tenebrio molitor), B. bassiana, and some common strawberry fungicides
Compatibility of B. bassiana and fungicides Dead Infected Mean percent mortality/infection 100 80 60 40 20 0 e d a a cd de ab ab cd cd a a bc bc de de cd c Average of 6 assays
Compatibility of B. bassiana and Pristine
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.
Acknowledgments Grower Dave Peck Technical assistance Jacob Conway Maria Murrietta Thomas Crottogini Sumanth Dara Pesticide Industry Curt Engle, United Phosphorus Eduardo Garcia, Chemtura Randy Martin, BioWorks Inc Pest infestations