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Dr. Paula Shrewsburypshrewsbury@umd.edu

Department of EntomologyUniversity of Maryland, College Park, MD

Encouraging beneficials to enhance biological control in nurseries

Biological Control in Nurseries ConferenceUniversity of Connecticut, Storrs, CT

June 21, 2016

Today’s topics

• Life history characteristics of natural enemies

• Needs of natural enemies

• Importance of diversity– Plant species– Structural complexity

• Practices to attract and retain beneficials

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Specialist• an organism that feeds on only one type of prey or host

Generalist• an organism that feeds on more than one type of prey or host

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Omnivore• an organism that feeds on both animal (insect prey) and plants (nectar and pollen, seeds)

Many natural enemies are omnivores and need alternative food sources such as nectar and pollen

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Many natural enemies are pollinators

Many pollinators are natural enemies

R. Waterworth, UMDM. J. Raupp, UMD

P.M. Shrewsbury, UMD

Practices to conserve natural enemies and pollinators should be similar

Natural Enemies

RefugesMicroclimates

Alternate food sources(prey, nectar, pollen)

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Conservation Biological Control

The deliberate attempt to maintain beneficial organisms in the nursery or landscape habitat

1. Enhancement of the habitat to attract and retain natural enemies and promote natural enemy survival and reproduction

2. Avoidance of activities that are harmful to or disrupt natural enemies

Plant Diversity can be estimated different ways

•Species richness - number of plant species

•Structural complexity – vegetation found in a three dimensional space

Landscape biodiversity is important!

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Raupp et al. 2001

ground cover or turfherbaceous plants

shrubs

understory

overstory

Structural complexity

Shrewsbury and Raupp 2000, Environmental Entomology

Structural complexity = 70

Structural complexity = 225

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Azalea Lace BugStephantis pyrioides

ground cover or turfherbaceous plants

shrubs

understory

overstory

Structural complexity

Shrewsbury and Raupp 2000, Environmental Entomology

Structural complexity = 70

Structural complexity = 225

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Simple Complex0

100

200

300

400

500

600

700

800

900

Nu

mb

er o

f L

ace

Bu

gs

Abundance in simple and complex landscapes

Shrewsbury and Raupp 2005

Predator group or taxa Simple Complex PGeneralist predators 13.1 ± 2.6 21.8 ± 2.6 0.0273

Spiders 24.7 ± 5.2 40.6 ± 5.4 0.0467

Anyphaenidae 4.93 ± 1.1 25.0 ± 2.5 0.0001

Thomisidae 1.58 ± 1.1 8.31 ± 2.9 0.0029

Theridiidae 9.28 ± 3.7 2.63 ± 0.7 0.0799

Oxyopidae 3.64 ± 2.2 0.68 ± 0.2 0.1111

Salticidae 3.97 ± 1.2 2.31 ± 1.0 0.2976

Phalangidae 0.38 ± 0.2 1.32 ± 0.4 0.0612

Gryllinae 1.36 ± 0.7 6.63 ± 1.8 0.0010

Oecanthinae 0.27 ± 0.2 1.73 ± 0.6 0.0139

Forficulidae 1.14 ± 0.5 1.24 ± 0.3 0.8720

Formicidae 4.72 ± 1.5 6.44 ± 1.4 0.4185

Miridae 0.27 ± 0.1 0.02 ± 0.0 0.0140

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Habitat_____________

Predator taxa Simple Complex____________________________________________________

Anyphaenidae (Anyphaena celer) 149.0 757.0Thomisidae (crab spider) 0 0Miridae (Rhinocapsis vanduzeei) 14.2 38.7Miridae (Stethoconus japonicus)** 59.7 2.9Anthocoridae (Orius tristicolor) 7.8 0Oecanthinae (Oecanthus fultoni) 4.1 27.0Gryllinae (Gryllus spp.) 0 0Forficulidae (Forficula auricularia) 26.3 28.9__________________________ _____ _____TOTAL 261.0 854.4

Predator Pressure Index = Abundance *Feeding rate

Shrewsbury and Raupp 2005

0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25

Predation Pressure Index (log10

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Nu

mb

er o

f S

. p

yrio

ides

(lo

g10

) Simple Complex

By having more voracious predators in a landscape fewer lace bugs survive

P<0.01, r2 = 0.58

Shrewsbury and Raupp 2005

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Structural complexity

Plant species richness

RefugesMicroclimates

Alternate food sources(prey, nectar, pollen)

Add flowers

to landscapes

Shrewsbury et al. 2004, IJEES

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Conservation strips in Golf Courses

Tee

Green

Fairway Rough

Frank and Shrewsbury 2004, Enviromental Entomololgy

Flowering plants provide habitat and

alternate food resources for

natural enemies

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Size and arrangement of landscape beds

• How big do the conservation beds have to be?

• How close do the conservation beds have to be?

– Habitat patches that are bigger and closer to other patches tend to be better than smaller, isolated patches

– However, every plant counts – Clumps of plants of the same species, within patches

tends to be better than single plants

Plant Selection: Bloom period

From: Xerces Society – Pollinator-Friendly Plants – Mid-Atlantic Region at: http://www.xerces.org/pollinator-conservation/plant-lists/

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Sweet Alyssum

Coreopsis

Switchgrass

Plant Selection: Floral and Plant Architecture

Gaillardia

Liatris Yarrow

Plant Selection – Native or Exotic• Function of the plant

– Will it survive / thrive in the habitat?

– Quality and availability of the pollen and nectar

– What does it attract and support?

• Maintenance requirements

• Avoid invasive or aggressive species

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Plant Selection: type and species

• Plant / flower species– Research-based information

• Trees, shrubs, vines, wildflowers, herbs, perennials, annuals– Annuals tend to not be good sources of nectar and pollen, but there are exceptions (see: Protecting and enhancing pollinators in urban landscapes…)

• Diversify!

Frank, Shrewsbury, & Esiekpe, 2008 Environmental Entomology (37:2)

MD Native plant species tested to determine their attractiveness to natural enemies

Common name Scientific name Family

Common milkweed Asclepias syriaca Asclepiadaceae

Butterfly weed Asclepias turberosa Asclepiadaceae

Threadleaf coreopsis Coreopsis verticillata Asteraceae *

Hyssopleaf thoroughwort Eupatorium hyssopifolium Asteraceae *

Spotted horsemint Monarda punctata Lamiaceae *

Narrowleaf mountain mint Pycnanthemum tenuifolium Lamiaceae *

Skullcap Scutelaria integrifolia Lamiaceae

Switchgrass Panicum virgatum Poaceae

Indiangrass Sorghastrum nutans Poaceae

Little bluestem Schizachyrium scoparium Poaceae

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www.croatianworld.net

Coreopsis verticillata

Eupatorium hyssopifolium

www.ct-botanical-society.org

Monarda punctata

groups.ncf.edu

Pycnanthemum tenuifolium

www.ct-botanical-society.org

“Winners” -MD Native Insectary

Plants

Frank, Shrewsbury, & Esiekpe, 2008 Environmental Entomology (37:2)

Eupatorium perfoliatum L.

Monarda punctata L.

Silphium perfoliatum L.

Potentilla fruticosa auct. non L.

Coreopsis lanceolata L.

Spiraea alba Duroi

Agastache nepetoides (L.) Kuntze

Anemone canadensis L.

Angelica atropurpurea L.

MI Native Beneficial Insectary Plants

Cup plantSilphium

perfoliatum L.

http://nativeplants.msu.edu

Canada anemoneAnemone

canadensis L.

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Shrubby cinquefoil Potentilla fruticosa auct. non L.

MeadowsweetSpiraea alba Du Roi

Yellow giant hyssop Agastache nepetoides (L.) Kuntze

AngelicaAngelica atropurpurea L.

MI Native Beneficial Insectary Plants

http://nativeplants.msu.edu/pdf/E2973.pdf

-Native plants

-Pollinators and natural enemies

-Table of plants, bloom times, and rating of attractiveness to natural enemies and pollinators

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From: MSU – Attracting Beneficial Insects with Native Flowering Plants at: http://nativeplants.msu.edu/pdf/E2973.pdf

Plant Selection: Plants to conserve beneficials

POLLINATOR PLANTS Mid-Atlantic Region

• http://www.xerces.org/pollinator-conservation/plant-lists/

• Recommended native plants that are: • highly attractive to pollinators

such as native bees, honey bees, butterflies, moths, and hummingbirds

• well-suited for small-scale plantings in gardens, on business and school campuses, in urban greenspaces, and in farm field borders

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http://www.xerces.org/books/

“Protecting and enhancing pollinators in urban landscapes for the US North Central Region”

-Provides information for landscapers and gardeners who want to attract pollinators and protect them when implementing pest management tactics-Plant lists-Timing of pesticide trts

http://msue.anr.msu.edu/resources/how_to_protect_and_increase_pollinators_in_your_landscape

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Production Nurseries

• Nursery manipulations to increase structural complexity and plant species diversity, and favorable management practices

– Cover crops

– Grass alleys with flowers

– Hardwood mulch groundcover over weed cloth

– Pot-in-pot planting method

– Conservation strips / flowering plants

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• Nursery manipulations to increase structural complexity and plant species diversity, and favorable management practices

– Cover crops

– Grass alleys with flowers

– Hardwood mulch groundcover over weed cloth

– Pot-in-pot planting method

– Conservation strips / flowering plants

Benefits of cover crops•Attract and retain natural enemies (plant species richness, structural complexity)

•Reduce insect / mite pest damage

•Suppress plant parasitic nematodes

•Weed suppression

•Increase organic matter for soil improvement

•Root penetration to alleviate soil compaction

•Improve water movement

•Reduce soil erosion

•Addition of nitrogen (N) by N-fixing legume cover crops

•Alters nitrogen cycling by taking up N in the fall (likely reducing N leaching) and releases it in the spring when trees and shrubs need N

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Nursery Cover Crop Project

Experimental design• Cover crops were evaluated in 4 types of areas

common to most field nurseries 1) tree row bare zones 2) tree row fallow areas 3) grass alleyways4) open field areas

• Treatments– Cover crop species,combinations, and planting time

Tree

Row

Grass Alley

Grass Alley

Grass Alley

Bare Zone

Fallow AreaT

ree R

owT

ree R

ow Fallow Area

Nursery Cover Crop ProjectForage radish, Raphanus sativus (Brassica)

• Evaluate for bare zone tree row, fallow tree row, and open field studies

• winter or spring annual• ~18” height• root penetration to alleviate soil compaction• weed suppression (fall, spring)• organic matter for soil improvement• alters N cycling by taking up N in the fall

(likely reducing N leaching) and releases it in the spring when trees and shrubs need N

• not been evaluated for its benefits to pest insect suppression

• no evidence of attracting deer, rabbit, or other rodents

• Seed source: Steve Groff, Cedar Meadow Farm, Holtwood, PA (steve@cedarmeadowfarm.com)

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Bare Zone Tree Row Study Forage radish, Raphanus sativus (Brassica)

Fall

Nursery Cover Crop ProjectCrimson clover, Trifolium incarnatum (Legume)

• Evaluate for bare zone tree row and fallow tree row studies

• winter annual legume• ‘Dixie’ ~ 18” height• source of slow-release N when it

dies in summer• makes soil P available• rapid growth in cool weather• weed suppression (fall, spring)• attractive to natural enemies ,

pollinators• shade tolerant• positive reseeding potential making

it effective as a living cover in nurseries

Dave Clark, USDA ARS

/www.tarleton.edu/

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Bare Zone Tree Row Study Crimson clover, Trifolium incarnatum (Legume)

Fall

Nursery Cover Crop ProjectAlyssum, Lobularia maritima (Brassicaceae)

• Evaluate for bare zone tree row studies

• Annual, small white flowers in summer

• Low growing, ~4-8” height

• Known to attract to natural enemies

www.crd.bc.ca

www.livingexpression.com

farm4.static.flickr.com

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Bare Zone Tree Row StudyAlyssum, Lobularia maritima (Brassicaceae)

Summer

Nursery Cover Crop ProjectBuckwheat, Fagopyrum esculentum (Polygonaceae)

• Evaluate for bare zone tree row studies

• Warm season annual, 2-4’ height, broad leaf

• Fast growing• Long bloom time• High nectar production• Known to attract to natural

enemies, pollinators• Weed suppression• No significant soil benefits• Low water requirement

nativeplants.msu.edu

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Bare Zone Tree Row StudyBuckwheat, Fagopyrum esculentum (Polygonaceae)

Summer

Benefits of cover crops•Attract and retain natural enemies (plant species richness, structural complexity)

•Reduce insect / mite pest damage

•Suppress plant parasitic nematodes

•Weed suppression

•Increase organic matter for soil improvement

•Root penetration to alleviate soil compaction

•Improve water movement

•Reduce soil erosion

•Addition of nitrogen (N) by N-fixing legume cover crops

•Alters nitrogen cycling by taking up N in the fall (likely reducing N leaching) and releases it in the spring when trees and shrubs need N

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Nursery Cover Crop ProjectGrass Alley Treatments

Tall FescuesFine Fescues No mow mix

Nursery Cover Crop ProjectGrass Alley Treatments

• Main treatment:

– Tall fescue mix

– Fine fescue mix (Chewings, Hard, Red)

– No Mow Lawn Mix (Prairie Nursery) (mix of hard and red fescues)

• Subplot treatment:

– New Zealand White Clover

– Birdsfoot Trefoil, Lotus corniculatus Empire – low growing, prostrate habit

Benefits: Reduced mowing; floral resources for natural enemies and pollinators, nitrogen fixation

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• Nursery manipulations to increase structural complexity and plant species diversity, and favorable management practices

– Cover crops

– Grass alleys with flowers

– Hardwood mulch groundcover over weed cloth

– Pot-in-pot planting method

– Conservation strips / flowering plants

Conventional:• Weed cloth

groundcover

Alternative:• Wood mulch over

weed cloth

Effects of ground cover type on arthropod dynamics

•Hypotheses: 1) Adding mulch as a ground cover will increase alternate prey and natural enemy abundance compared to weed cloth 2) Herbivore mortality will be greater in mulched plots compared to weed cloth

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Conventional:• Pots set above

ground

Alternative:• Pot-in-pot planting

system

Hypotheses: 1) Plants in the pot-in-pot system are more accessible to natural enemies 2) Herbivore mortality will be greater compared to above ground

Effects of pot position on arthropod dynamics

Arthropod sampling:

• Pitfall traps in ground (wood mulch and weed cloth)

• Pitfall traps in containers in soil (above and pot-in-pot)

Predation / Herbivore survival:

•Predation of prey on foliage and on ground within containers

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Most Common Alternative Prey

Collembola

Phoridae

Sciaridae

Flies

Most Common Natural Enemies

Staphylinidae

FormicidaeFormicidae

Carabidae

Spiders

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Conclusions

• Adding wood mulch appears to increase predator abundance which is likely associated with greater alternate prey abundance

• The pot-in-pot planting method appears to increase predator accessibility to prey

• Soil dwelling herbivores appear more susceptible to predation than foliar herbivores

• Nursery manipulations to increase structural complexity and plant species diversity, and favorable management practices

– Cover crops

– Grass alleys with flowers

– Hardwood mulch groundcover over weed cloth

– Pot-in-pot planting method

– Conservation strips / flowering plants

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Efforts towards the conservation of natural enemies and pollinators

• Obj. To evaluate the impact of beds of flowering plants (conservation strips) in production nurseries on:

• Pollinator abundance and diversity

• Natural enemy abundance and diversity

• Biological control services

R. Waterworth, UMD

Shrewsbury and Waterworth, current study

Raemelton Farm and Ruppert Nursery

Efforts towards the conservation of natural enemies and pollinators

• Based on research that demonstrated attraction of pollinators and/or natural enemies

• Seed mix of annual and perennial flowers– Approx. 18 spp.– Select percentage seed of each species

• Commercially available seeds

• Something blooming throughout the seasonShrewsbury and Waterworth, current study

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Conservation Biological Control

The deliberate attempt to maintain beneficial organisms in the nursery or landscape habitat

1. Enhancement of the habitat to attract and retain natural enemies and promote natural enemy survival and reproduction

2. Avoidance of activities that are harmful to or disrupt natural enemies

• Choose pesticides wisely!– Low toxicity, selective, short residual activity, IGR – EPA Reduced Risk or OMRI listed pesticides– Read and follow label directions carefully!

• Integrate alternative control measures (IPM)– Cultural, mechanical, or biological tactics

Avoid activities that are harmful to or disrupt natural enemies

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Recommendations:• Increase structural complexity

– More plants at different vegetational strata

• Increase plant biodiversity– More plant species, families– Include trees, shrubs, vines, perennial flowers and herbs

• Add flowers– vary architectural complexity– provide overlapping and season long bloom

• Plant selection should be based on proven attractiveness and the natural enemies and pollinators they attract

• Alter management practices – Flowering conservation strips, wood mulch,

pot-in-pot, cover crops

• Avoidance of activities harmful or disruptive to natural enemies

THANK YOU!

Paula Shrewsbury, Ph.D.

University of Maryland

pshrewsbury@umd.edu

Acknowledgements:Mike Raupp, Univ. of MarylandCliff Sadof, Purdue Univ.Dave Smitley, Michigan State Univ