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Mile-a-Minute Update
Judy Hough-Goldstein
Dept. Entomology & Wildlife Ecology University of Delaware
Mile-a-minute weed: Persicaria perfoliata (AKA Polygonum perfoliatum)
Annual vine
Impacts: – Inhibits reforestation – Interferes with recreation – Reduces wildlife habitat – Outcompetes native flora
White Clay Creek State Park, Delaware July 23, 2003
• Six year seed bank
• Dispersed by birds,
deer, water
Seedlings in May
Cluster of achenes (single-seeded fruits)
Origin Native to: China Japan Korea India Bangladesh Nepal Bhutan Burma (Myanmar) Thailand Vietnam the Malay Peninsula Taiwan the Philippines Also found in: Turkey eastern Russia
Establishment in U.S. • Nursery in York Co.,
PA, 1930s
• Before 1980: five counties in PA & parts of MD
C. Bargeron, EDDMaps
Introduced,1930s
Fall 2011: New Hampshire – present 2 yrs. (Doug Cygan, Inv. Sp. Coordinator)
• Fall 2012 : “one small vine, approximately 3-feet long … likely that this site can and will be eradicated over time”
• “Early Detection – Rapid Response” – Somewhat early detection - Persistent response
Biological Control Program – US Forest Service, 1996
MAM in China (Ding Jianqing, Wuhan Botanical Garden) MAM in United States (Les Mehrhoff, Conn., IPANE)
Rhinoncomimus latipes Korotyaev,1997
• Host specificity • China: 49 plant species • Delaware (1999-2003):
28 species, mostly Polygonaceae
• Permit for field release: 2004 Adult weevil ~2 mm long
E. Lake
Eggs
E. Lake E. Lake A. Diercks
Larvae
D. Palmer
D. Palmer & A. Diercks
Pupae
D. Palmer & A. Diercks
Adults
K. Paras A. Diercks
Field signs
E. Lake
Note: no damage to P. sagittata (arrow-leaf tearthumb)
“Damaged nodes”
Potential for exponential population growth
– ~3-4 generations – Continual egg-laying, May through
mid-August – Each weevil can lay ~150 eggs – Release of 200 weevils in May:
• 100 ♀ → 15,000 weevils in June • 7,500 ♀ → 1,125,000 weevils in July • 562,500 ♀ →84,375,000 weevils in August
Weevils reared since 2004: NJ Dept. Ag Phillip Alampi Beneficial
Insect Lab
Oviposition container Larval development containers
Top state 2004 600 DE 2005 13,902 NJ 2006 28,665 NJ 2007 38,425 NJ 2008 54,311 NJ 2009 67,358 NJ 2010 75,824 PA 2011 77,150 PA 2012 76,680 NY
Total
432,915
2011 + 2012
Weevil releases, 2004- 2010
Introduced, 1930s Mile-a-minute weed
EDDMapS
EDDMapS
PA 37,400 NY 31,750 NJ 18,380 WV 11,800 MA 10,500 VA 10,500 CT 10,400 NC 7,200 DE 6,100 MD 6,000 RI 3,800
Evidence of impact: NJ releases, 2004-2005
2007
2006
Mark Mayer,, NJDA
July 2005 May 2006
Abbott’s Meadow, NJ - ~7,000 weevils, 2005
October 2006 October 2007
Mark Mayer
White Clay Creek, DE, Release Site 2: early Sept. 2005
Note bush to right of deer blind, covered by MAM (2005)
Mid-August, 2008 – MAM, Rubus spp., Japanese stilt grass
Release of apical dominance and response to larval feeding:
shorter vines
MAM less able to compete with resident plant community
Competition with Rubus triphyllus
Conditions that affect “success”
• Plant community present with MAM – Competition (space, nutrients, light, water)
• Weather (spring, summer)
– Temperature – Moisture
Plants without competition
Stem circumferences at base averaged 2.6 - 4.2 cm
Control Cage #5 Outside the cage
Base of plants, Oct. 2, 2006
Restoration planting to enhance plant competition: Euthamia graminifolia
(flat-top goldentop) and elms
• Ellen Lake, Ph.D. 2011 • 4 treatments: control, low & high
density Euthamia, low-density + elms
• All with weevils • With and without a single pre-
emergent herbicide application • Impact on MAM and plant community
• Three sites: – Laurels – Waterloo Mills – Crosslands
• MAM seedlings, % cover monthly
• Resident community (% cover by species), Fall 2010 (2 yr) and 2012 (4 yr) – and continuing
Planted Fall 2008
Euthamia plus elms
How long does it take? Clewly et al. 2012: 7 years
Species richness
• 2010: total 127 plant species from 48 families, ~75% native – No difference by treatment – % cover a better measure
Results differed by site
- more Euthamia in Control than in planted plots - herbicide + weevils restored native vegetation - planting treatments had no effect
• MAM suppressed at all three sites
• Native plant cover at Laurels, 2010:
Waterloo Mills & Crosslands: Native plant % cover (2010)
Trt P=0.0025 Herbicide P<0.0001 Trt*Herbicide P=0.2601
Japanese stiltgrass % cover (2010)
Trt P=0.0012 Herbicide P<0.0001 Trt*Herbicide P=0.1816
Restoration Ecology (submitted)
Laurels elm plot, Sept. 2012
Kiri Cutting, MS 2011 • Native seed mix, with and without weevils (excluded using systemic insecticide) • Planted spring 2009
• 25% Canada Wild Rye
• 20% Big Bluestem
• 15% Switchgrass • 20% Ox Eye Sunflower
• 20% Black Eyed Susan
Native Seed Mix:
Mile-a-minute percent cover over three years
K Cutting
Greatest effect on MAM: • 2009: Weevils + Seed • 2010: Weevils • 2011: Seed (main effect
significant, P=0.0084)
Restoration Ecology in press
Weevil behavior Sun versus shade
Hough-Goldstein & LaCoss (Arthropod-Plant Interactions, 2012) • More weevils and feeding damage in sun than in shade Smith & Hough-Goldstein (J. Insect Behavior, 2012) • In greenhouse, response to sun can be >response to host plant
2011 and 2012 experiments in dispersal and host plant colonization
HG, Lake, D’Amico, & Berg (Environ. Entomol. 2012) • Weevils more likely to
colonize plants placed along forest edge than those out in open field
• Is R. latipes adapted to seek its host plant at the forest edge?
Lab-reared versus wild versus Chinese weevils
• Lab colony started in fall 2004 with ~20 weevils • Same genetic stock through present • Comparison in field cages (Amanda Stout)
F1 adults produced from lab & field eggs
0
5
10
15
20
25
30
35
40
45
50
Field Lab Field Lab
Sun Sun Shade Shade
Colony: P=0.4413 Sun vs. Shade: P=0.0015*
Current/future studies
• Interaction of mile-a-minute and weevils with moisture levels (Scott Berg) – Are drought-stressed plants more susceptible
to suppression by the weevil?
• Effectiveness in different geographical areas – Massachusetts to North Carolina
Acknowledgements
Scott Berg Kaity Handley Jeff Smith Amanda Stout Kiri Cutting Sam Nestory
Dick Reardon
Lab Group 2012