6/24/2016 1 Dr. Paula Shrewsbury [email protected]Department of Entomology University of Maryland, College Park, MD Encouraging beneficials to enhance biological control in nurseries Biological Control in Nurseries Conference University 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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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…)
• 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
• 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 ([email protected])
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Bare Zone Tree Row Study Forage radish, Raphanus sativus (Brassica)
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