Manipulating Plant Diversity as a Warm Season Turf Pest Management Strategy

Transcription

1 Manipulating Plant Diversity as a Warm Season Turf Pest Management Strategy Adam G. Dale 1, Jason K. Kruse 2, Basil Iannone 3 1 Entomology & Nematology, 2 Environmental Horticulture, 3 School of Forestry & Resource Conservation UF/IFAS - Gainesville, FL

2 Urban plants provide benefits Benefit people Reduce temperatures Air filtration Recreational space Aesthetic enhancement Benefit the environment Carbon sequestration Air & water filtration Wildlife habitat

3 Unfortunately Herbivorous insects are more abundant & damaging on trees & shrubs urban landscapes The evidence Azalea lace bug, Stephanitis pyrioides Oak lecanium scale, Parthenolecanium quercifex Gloomy scale, Melanaspis tenebricosa Others Raupp et al. 2010

4 Unfortunately Insect pests of turf are common & almost exclusively an urban landscape problem The evidence Southern chinch bug, Blissus insularis Tropical sod webworm, Herpetogramma phaeopteralis Hunting billbug, Sphenophorus venatus vestitus Others Florida has the largest turf industry in the U.S.

5 Why do insect pests matter? People don t want damaged turf Marketability Pest-damaged plants provide reduced services Air & water filtration Cooling Recreation Wildlife habitat Aesthetic enhancement Impervious surfaces are rapidly replacing vegetation

6 Current management Relies on insecticides particularly in warmer climates Calendar-based applications Cover-spray applications Management & remediation of damaged turf may offset the benefit turf provides Additional irrigation & fertilization Replacement

7 Current Climate Non-target effects of the most commonly used insecticides present challenges & uncertainty Neonicotinoids Pyrethroids Continued urbanization & population growth is putting pressure on resource conservation Water Natural resource protection

8 Pest Management Priorities Resource conservation & plant health are increasingly important We need new IPM tactics that reduce management inputs and pest damage

9 The Role of Plant Diversity Plant diversity & complexity affect insects Herbivores Natural enemies Resource concentration hypothesis More difficult for pests to locate hosts & move from plant to plant in diverse stands Associational resistance Enemies hypothesis Diverse plantings may attract & harbor more abundant & diverse natural enemies Tahvanainen & Root 1972 Barbosa et al. 2008

10 Plants in Urban Landscapes Highly manipulated plant communities Often dominated by a few species Urban forests 1-5 species make up over 50% of forest composition Urban Forest Gainesville, FL Species % of forest Pinus taeda 17% Pinus elliottii 12% Quercus laurifolia 8% Quercus nigra 7% Acer rubrum 7% Urban Forest Raleigh, NC Species % of forest Lagerstroemia indica 20% Acer rubrum 17% Quercus phellos 12% Pinus taeda 6% Betula nigra 5% Andreu et. al. 2017

11 Plants in Urban Landscapes Highly manipulated plant communities Often dominated by a few species Urban forests 1-5 species make up over 50% of forest composition 4.4 million acres of turf in Florida 6-10 species 5 genera 10 genotypes of each Florida Turfgrass Production Type % No. species St. Augustinegrass 51% 1 Bahiagrass 33% 1 Bermudagrass 7.4% Multiple Zoysiagrass 5.1% 2-3 Centipedegrass 3% 1 Satterthwaite et al. 2007

12 St. Augustinegrass Stenotaphrum secundatum 51% of FL sod production >70% of residential turf in FL Currently 6 commercially produced & widely used cultivars Vegetatively produced, planted, & maintained as genotypic monocultures Kevin Kenworthy

13 St. Augustinegrass Cultivars Stenotaphrum secundatum >80% is Floratam Classic Palmetto Bitterblue Seville Captiva Floratam

14 St. Augustinegrass Diversity Homogenized to maintain desired traits: Aesthetic traits Cultural requirements Pest tolerance/resistance Resource concentration & Enemies hypotheses *Diverse plantings can also provide tolerance or resilience to pests

15 Mixing Warm Season Turf Inter-specific mixtures St. Augustine Bahia Zoysia Bermuda Intra-specific mixtures Mixing commercially produced cultivars Genotypic diversity can be an effective pest management strategy Tooker & Frank 2012

16 Insect Pests of St. Augustinegrass Southern chinch bug, Blissus insularis Sap-feeding pest Primarily feeds on St. Augustinegrass Pest managers make 6 wall-to-wall insecticide applications/year of pyrethroids and/or neonicotinoids

17 St. Augustinegrass Pest Management Objective 1. Determine the effect of genotypic mixtures on B. insularis fitness Hypothesis: Increasing genotypic diversity will reduce SCB fitness and damage Objective 2. Determine the effect of genotypic mixtures on St. Augustinegrass quality & performance Hypothesis: Diverse stands will be indistinguishable & provide greater services than monocultures

18 Experimental Design 6 St. Augustinegrass cultivars Floratam Palmetto Bitterblue Classic Seville Captiva Treatments: Monoculture (M1) Mixture of 2 cultivars (M2) Mixture of 4 cultivars (M4) 15 replicates of each treatment 15 unique mixtures of 2 and of 4 cultivars

19 Randomized Complete Block Design 86 ft M1 M3 M2 M1 M2 M3 M3 M2 M1 M3 M2 M3 M1 M2 M3 M2 M1 M3 M1 M2 M1 A 86 B ft C. D D A C B B A D. C A B C. D D A C B M1 A C M2 B D A M3 D B M1 M2 M3 M1 B D. C A D M2 M3 M2 M2 M3 M1 M3 D C A B D C B A M3 M1 M1 M3 M1 M2 M2 C A B D A B C. D M3 M2 M1 B A D. C D C B C A A B D B C D C B B A B A D. C D C B A B A C A A B C. D D C D C C A B B A B 10 A C. X 10 D D. Plots C A of D plugged St. Augustinegrass

20 Southern Chinch Bug Management Objective 1. Determine the effect of genotypic mixtures on B. insularis fitness & abundance Field surveys for B. insularis and natural enemy abundance Greenhouse & lab trials to compare life history and fitness when developing on resistant, susceptible, or genotypic mixtures

21 The Plant Side of Things Objective 2. Determine the effect of genotypic mixtures on St. Augustinegrass quality & performance Aesthetic traits Cultural practices Ecosystem services Can people tell a difference?

22 Future Directions UF Environmental Horticulture/Entomology M.S. student Brianna Whitman How do cultivar mixtures affect B. insularis management & St. Augustinegrass performance?

23 Insect Pests of St. Augustinegrass Caterpillar pests Fall armyworm, Spodoptera frugiperda Tropical sod webworm, Herpetogramma phaeopteralis Polyphagous on warm season turf Increasingly damaging

24 Caterpillar Management Objective 1. Determine the effect of genotypic mixtures on caterpillar fitness Hypothesis: Increasing St. Aug. diversity will reduce caterpillar fitness Objective 2. Determine the effect of genotypic mixtures on biological control of H. phaeopteralis Hypothesis: Increasing St. Aug. diversity will increase predation & parasitism of caterpillar pests

25 Experimental Design 6 St. Augustinegrass cultivars Floratam Palmetto Bitterblue Classic Seville Captiva Treatments: Monoculture (M1) Mixture of 2 cultivars (M2) Mixture of 4 cultivars (M4) 15 replicates of each treatment 15 unique mixtures of 2 and mixtures of 4 cultivars

26 Caterpillar Fitness Effect of genotypic mixture diets on TSW fitness Rear caterpillars on a diet of each St. Aug. treatment: M1, M2, M4 27 o C, 70% RH, 14:10 Light:dark cycle Track development rate, body weight, days to pupation, pupal weight, sex ratio

27 Preliminary Results Fall armyworm, S. frugiperda preliminary results F 2,24 =4.83, P= Floratam

28 Percent Survival % Survival to Pupation Preliminary Results Tropical sod webworm, H. phaeopteralis development A AB P<0.05 M1 M2 M B Mono M M St. Augustinegrass Time (days) Diet

29 Future Directions Objective 1. Determine the effect of genotypic mixtures on H. phaeopteralis & S. frugiperda fitness Development on mixed diets Host choice assays M.S. student, Ethan Doherty Development on mixed plantings UF Entomology & Nematology Objective 2. Determine the effect of genotypic mixtures on biological control of H. phaeopteralis in the field

30 Summary Genotypic mixtures of St. Augustinegrass are a plausible IPM tactic Industry professionals cannot differentiate mixtures from monocultures Fall armyworm body size is reduced when fed mixtures compared to most common monoculture As St. Augustinegrass genotypic diversity increases, tropical sod webworm survival decreases

31 Implications St. Augustinegrass genotypic mixtures may help make urban landscape management more sustainable Reduce insecticide applications Increase services provided by turf Increase turfgrass resilience May also have implications for disease, weed, and drought stress management

32 Thank you Students contributing to this work Masters students: Ethan Doherty, Brianna Whitman Undergraduate student: Rebecca Perry Collaborators Jason Kruse, Basil Iannone, Tatiana Sanchez Support Kevin Kenworthy R.B. Farms LLC UF/IFAS Entomology & Nematology Department Florida Nursery, Growers & Landscape Association UF/IFAS Early Career Research Grant Lab website: dalelab.org