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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