165

Impact evaluation of Galerucella ssp. as a biocontrol agent ofpurple loosetrife () in Goodyear Swamp Sanctuary

Scott Fickbohm1

ABSTRACT

This report constitutes the continued monitoring ofthe effort to biologically control purple loosetrife (Lythrum salicaria) with Gaierucella spp. that was started in 1996. The study followed the prescribed protocols set forth by Dr. Bernard Blossey ofCornell University. Data recorded in accordance with these protocols, as well as anecdotal observations made during the spring through fall months of the year 2000, was used in a quantitative and qualitative comparison from prior years. The results ofthis comparison were used in assessing Gaierucella 's ability to establish a viable population as well as their impact on the proliferation, mortality and reproductive success of purple loosetrife and their consequent value as a biocontrol agent. This information will also be part of a growing data base designed to validate additional use ofthe Gaierucella spp. in combating the further spread ofloosetrife infestations associated with Lake Otsego and other wetlands nationwide.

INTRODUCTION

Biological control is a technique commonly used among wildlife managers to control a pest species when more conventional means prove ineffective, too costly, or when there are environmental or human health risks. This practice involves the introduction of a natural enemy to a population of pest species with the aim ofcontaining its proliferation (Skinner, 1996).

Purple loosetrife (Lythrum saiicaria), a perennial wetland plant, is such a pest species. Introduced from Europe in the 1800s, it has quickly spread and infested many ofNorth America's wetlands (Stuckey, 1980). Originally transported from its native environment in the ballasts of ships coming to America and Canada from Europe, purple loosetrife was later intentionally transported further inland by settlers who valued its ornamental beauty and supposed medicinal properties (Thompson et ai., 1987).

In its native environment purple loosetrife populations are controlled by a diverse community (Blossey, 1995). These natural predators were not transported with the purple loosetrife at the time ofintroduction. Free from predation, the plants natural capacity to out compete native flora, coupled with a ability to produce over two million seeds per adult per year (Welling et ai., 1990), has resulted in large monotypic stands at the expense of the native flora. This reduction in indigenous primary producers also resulted in a corresponding drop in those populations - whether arthropod, mammal, or avian - that use that vegetation for food, shelter, or breeding/nesting sites (Thompson et ai., 1987).

1 Cooperstown Lake and Valley Garden Club intern, summer 2000. Present affiliation: SUNY Binghamton EEB Graduate Program. 166

More traditional methods of exotic vegetation control such as physical removal, prescribed bums, water level management, and herbicides have proven largely ineffective against large stands ofpurple loosetrife (Malecki, 1979). This is largely a result ofthe large annual seed production of each adult and the ability of those seeds to remain viable for many years, as well as an increased gennination rate in areas that have experienced a physical disruption (Rachich, 1999). Such methods often need to be applied annually - compounding costs, and frequently result in the destruction ofnon-target species.

The use of several species to control purple loosetrife populations has been in effect for over eight years (Blossey, 1997). In order to guarantee a safe and effective means of biological control, these species were studied intensely for years to insure that they fulfilled requirements of host-specificity and had the ability to cause significant damage to purple loosetrife populations (Skinner, 1996). The species identified were Hybolius transverssovittatus, a root-mining weevil; and G. pusilla, two leaf-eating ; and Nanophyes marmoratus and N brevis, two flower eating weevils (Malecki et al., 1993).

Through the assistance ofDr. Bernd Blossey (Director ofbiological control ofnon­ indigenous plant species at Cornell University) it was decided in 1996 to combat the purple loosetrife infestation at Goodyear Swamp Sanctuary through the use ofboth Galerucella calmariensis and G. pusilla (Jorczak, 1996). In accordance with the protocols prescribed by Dr. Blossey (1997) one hundred Galerucella spp. were released in the anticipation that the damage inflicted to the meristematic regions and leaves of the loosetrife would result in defoliation, impaired growth, decreased seed production, and increased mortality, effectively stopping the spread of the population (Blossey et al., 1994).

METHODS

All data collected and recorded during the spring-fall months of2000 followed the established protocols. This method provides year to year continuity from in the assessment of Galentcella spp impact.

Figure 1 is a map of Goodyear Swamp Sanctuary and shows the five sample plots. Quadrats 1 and 2 were sites of the original release. Quadrats 3, 4, and 5 were established to estimate the Galerucella spp. spatial distribution over time. "Fonn 1" (Appendix 1) provides general infonnation concerning site location, legal landowner and contact, road map to the site, a site and vegetation map, and insect release history. "Fonn 2" is split between the two times at which recorded observations are made: spring and fall. The Spring Quadrat Sampling Fonn (Appendix 2) includes population density within the established sites of the Galerucella beetles at different stages in their life cycle, population density ofthe purple loosetrife, percent cover and percent damage estimates, heights of the five tallest plants within the plot, and population estimates of other species within the plot - both plant and insect. The Fall Quadrat Sampling section (Appendix 3) of "Fonn Two" updates similar infonnation concerning the characteristics ofthe purple loosetrife population, as well as an analysis of each of the five tallest plants 167 4

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Figure 1. Map of Goodyear Swamp Sanctuary showing sampling sites. Sites 1 and 2 are where Galerucella spp. were stocked in 1997; sites 3-5 were used as controls and to evaluate the spread of Galerucella spp. inflorescences, and any peripheral species present. "Form 3" (Appendix 4) is simply a list of all other plant species within each plot (BlosseyI997). For a complete representation of Blossey's protocol refer to Austin (1998).

All data were collected from the five 1m2 plots established in '97-'98 and recorded on the above-mentioned forms.

RESULTS

All figures use abundance and frequency categories found in Table 1. It should be noted that a change from one category to the next can be the result of a substantial increase (or decrease) in frequency or abundance.

Spring Quadrat Sampling: The following comparisons were all made from data collected in 2000 to those in1999. Note that abundance category 1 represents an absence of eggs, larva, or adults. Egg abundance showed an increase in quadrats 1, 2, and 4 and remained constant in quadrats 3 and 5 (Figure 1). Larval abundance showed a decrease in quadrats 1 and 2 and remained constant in 3, 4, and 5 (Figure 2). Adult abundance increased in quadrat 5, and remained constant in 1,2,3, and 4 (Figure 3). The percent damage done to the purple loosetrife leaves by the Galerucella remained constant in all quadrats (Figure 4). The percent cover of purple loosetrife inside quadrats 1 and 2 increased, decreased in 3 and 4, and remained constant in quadrat 5 (Figure 5). The number of purple loosetrife stems per quadrat increased in 1,2, and 3 and decreased in 4 and 5 (Figure 6). 168

I Abundance Frequency Categories Categories 0 1 0 A- mid-point Opercent 1-9 2 1-5percent B- mid-point 2.5percent 10-49 3 5-25percent C- mid-point 15percent 50-99 4 25-50percent D- mid-point 37.5percent 100-499 5 50-75percent E- mid-point 62.5percent 500-1000 6 75-100percent F- mid-point 87.5percent >1000 7

Table 1. Categories prescribed in Blossey's (1997) protocol for abundance and frequency.

~ o I E~'------I ~ 4 +------~-__r_-r__------____I I Q) 3 I gell 21 +-~------,==-~----j -g 0 t=.:c=:J...m••IL:::::;==L_ if.. ;, .D c( 1998 1999 2000 I I Year ~ I ;0 quadrat 1 • quadrat 2 • quadrat 3 [BJ quadrat 4 quadrat 5 ! L Figure 1. Comparison of Galerncella spp. egg abundance from yearly spring sampling observations, abundance categories taken from Table 1.

~ o E3,------I ~ Q) 2 +------,....­ g 1 +-,---_ ca -g 0 +-...1..-_ ;, .D c( 1998 1999 2000 I Year

!0 quadrat 1 • quadrat 2 • quadrat 3 [!J quadrat 4 ~ quadrat 5 ! -l I Figure 2. Comparison of Galerncella spp. larval abundance from yearly spring sampling observations, abundance categories taken from Table 1. 169

~ o CIS ! 4 1------­ - (J 3 1------..--­ ~ 2 1-----­ 'gO+­:; 1 -I--=r=:J••• :l «.c 1998 1999 2000 Year

I0 quadrat 1 • quadrat 2 • quadrat 3 1m quadrat 4 ~ quadrat 51

Figure 3. Comparison of Galerncella spp. adult abundance from yearly spring sampling observations, abundance categories taken from Table 1.

~ I f 20 go ~ 15 +-----­ I .:: 0 ... CI 10 +- _ oJ!! ... III '5 () 5 -1-----­ c. 'E-6 0 -!--C:'.. 1998 1999 2000

10 Quadrat 1 • Quadrat 2 • Quadrat 3 IE Quadrat 4 ~ Quadrat 5 I Figure 4. Comparison ofpercent damage estimations to purple loosetrife leaves from yearly spring sampling observations, frequency mid-points taken from Table 1.

g 80..-- ---.

Ql :l 60 go ~ +------­ .:: 0 '0 CI 40 +------;:==--~==_------_== ... J!! l:: III '0 (J 20 +-__ c. 'E-6 0 +-..1...-­ 1998 1999 2000

i0 Quadrat 1 • Quadrat 2 IIQuadrat 3 [!i Quadrat 4 Ill! Quadrat 5 I

Figure 5. Comparison ofpercent coverage estimations ofpurple loosetrife plants from yearly spring sampling observations, frequency mid-points taken from Table 1. 170

100 -~ 80 60 ~ 40 .c I E 20 ::::l I C 0 -j---'--_ I 1998 1999 2000 I

I ~adrat 1 " • Quadrat 2 " (I Quadrat 3 " C3 Quadrat 4" ~ Quadrat 5-'J I ~- ______J Figure 6. Comparison of the number of purple loosetrife stems from yearly spring sampling observations.

Fall Quadrat Sampling: Percent cover of purple loosetrife decreased in all quadrats except for 3 and 4 (Figure 7) and number of stems (Figure 8) increased in all quadrats from spring 2000 to fall 2000. No inflorescences were observed in quadrats 1 and 2, those found in quadrat 3 were considerably less abundant, smaller, and had less buds per 5cm of stem than those found in quadrats 4 and 5 (Appendix 2). Other peripheral data such as heights ofthe five tallest plants in each quadrat, native flora and fauna present can be found in Appendices 1 and 2. (note: fall sampling was not recorded in 1999)

I \ I ~ 100 I

I 5 :~ I I.... en :=====------­ I , ~ ~ 40 +-----;== - I i '0 t.l I I i 2~ -\----1-__ ,

I spring' 00 fall' 00 ,I I I "0 Quadrat 1 • Quadrat 2 • Quadrat 3 I]Quadrat 4 ~ Quadrat 5 ! I ~----_---:======--======' ~ Figure 7. Comparison ofpercent coverage ofpurple loosetrife plants from spring and fall sampling 2000, frequency mid-points taken from Table 1. 171

120 ~ +--~~~~~~--~-~~~~~~----r---,--. -I 100 ~ 80 -r----~--~~~--~~--~~--~~~_ '0 60 +------<"-­ ~ 40 ~ 20 ~ 0 -r------'-­ spring '00 fall' 00

~ 1 0 Quadrat 1 III Quadrat 2 II Quadrat 3 em Quadrat 4 Quadrat 5 Figure 8. Comparison of stem number ofpurple loosetrife plants from spring and fall sampling 2000.

DISCUSSION

Data recorded for spring sampling 1999 were collected 5/1/99, and those recorded for Spring Sampling 2000 were collected 6/12/00. The effect of this six week difference is unclear in regarding the particular stage in the life cycle that different generations of Galerocella were in at either time, and their impact on the purple loosetrife, is unclear. It was very apparent that the increase in egg abundance resulted in a large increase of adults later in the summer. Observations, particularly in the area of quadrat 1 and 2 (original release sites), revealed large numbers of mating adults; at times it was difficult to find an adult that was not paired. As many as 20-30 pairs were observed on the upper portions of a single plant at this time. Such vigorous reproduction was obviously a factor in the Galerocella 's subsequent population increase as well as surpassing some critical mass per area where the fecundity of the female increases with population density as shown by Blossey (1999).

The habits ofthe beetle larva are not well known. The low numbers recorded during the spring sample 2000 may be a result of the observations being made at the wrong time of day or other unknown temporal or spatial aspects to their behavior.

It is also well worth noting that at the time ofthe observations of the spring sampling, areas surrounding the established quadrats did have significant adult Galerocella abundance. But due to the randomness of a somewhat patchy distribution, it did not fall within the quadrat. This may lead to a somewhat misleading estimation of the population based solely on the recorded data.

Although the Galerocella spp. population distribution is patchy if observed within a relatively small area (i.e. 5 meters sq.), it demonstrated clumped characteristics if viewed within the sanctuary as a whole. These areas of greater density were clumped around the original release sites I and 2. Throughout the summer the population grew outward from this focal point rather than having significant new colonization of patches established by migrating beetles. This pattern 172 of growth has been shown to be consistent with the migration patterns of Galerucella calmariensis, which were found to be strongly attracted to the presence of conspecifics when settling after dispersal (Grevstad, 1997).

Galerucella calmariensis has also been shown to have the ability to consistently locate purple loosetrife patches within 50 m, and be able to travel up to 850 m in search of a host patch (Grevstad, 1997). This would indicate that spring migrations from overwintering refuges will result in a wider dispersal creating a positive feedback cycle in which the Galerucella spp. populations will become dense during the summer feeding and mating season (increasing the number of individuals) followed by advancement into untouched loosetrife stands in the following spring and so on.

Direct quantitative comparison of the number of purple loosetrife stems can be misleading. The assumption that an increase in stem number is a reflection of a stand's robustness is often contrary to observation. This was the case in quadrats 1 and 2 where the number of stems increased from spring to fall 2000. The quadrats themselves had been almost completely defoliated by the fall sampling period. The plants response to such a reduction in photosynthetic ability was to produce additional shoots from their starch and carbohydrate reserves stored in their root systems. The result is an increased number of stems in a devastated quadrat. Plants in this state are unable to produce infloresences and may have a reduced chance of surviving continued herbivory after dormancy. It is worth noting that in the area of sites 1 and 2, swamp candles (Lysimachia terrestris), a native loosetrife, was evident for the first time in years. It had become practically extripated from the Sanctuary following the proliferation of purple loosetrife, but is currently rebounding. There was no sign of herbivory on that species.

An increase in percent cover ofpurple loosetrife may be the result ofroot resource allocation to compensate for moderate grazing. This was the case in quadrat 4 which underwent modest herbivory, sufficient to reduce the size, length, and number of infloresences and buds per inflorescence, but ultimately resulted with increased leaf production.

It is this type ofresponse by the purple loosetrife that is most insightful into the effectiveness of the Galerucella spp. as an effective biocontrol agent. While percent damage of purple loosetrife during the summer is an impressive visual sign of the Galerucella 's performance, it is the resilience ofthe purple loosetrife to the stress of herbivory that is a more reliable indicator of their effectiveness. Compared with anecdotal observations ofprevious years, where the stress created by grazing had been compensated for by the production of secondary growth leaves and infloresences by fall, current plant response to Galerucella herbivory has been insufficient to offset its impact. In fact, anecdotal annual observations place the summer of2000 as the first year when Galerucella has done substantial and lasting damage. This is an encouraging observation in regards to reducing the purple loosetrife population to a level where it is not a threat to native flora and its associated faunal communities.

For purposes of continuity, future observations (spring and fall) should be recorded at approximately the same of year to avoid any confounding effects that a temporal difference may have in the analysis of data. 173

REFERENCES

Austin, T. 1998. Biological control ofpurple loosetrife in Goodyear Swamp Sanctuary using Galerucella spp., summer 1997. 30th Ann. Rept. (1997), SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.

Blossey, R, RD. Schroeder, and R.A. Malecki. 1994 Host specificity and enviromental impact oftwo leafbeetles (Galerucella calmariensis and G. pusilla) for biological control of purple loosetrife (Lythrum salicaria). Weed Science 42: 134-140.

Blossey, R 1995. A comparison of various approaches for evaluating potential biological control agents using on Lythrum salicaria. BioI. Control 5: 113-122.

Blossey, B. 1997. Purple loosetrife monitoring protocol 2nd draft. Unpublished document. Dept. of Natural Resources, Cornell University.

Blossey, B. 1999. Mass rearing methods for Galerucella calmariensis and G. Pusilla (Coleoptera: Chrysomelidae), biological control agents ofLythrum salicaria (Lythracea). Journal ofEconomic Entomology 92:325-334.

Grevstad, F.S. 1997. Quantifying the effect ofdistance and conspecifics on colonization: experiments and models using the loosetrife beetle, Galerucella calmariensis. Oecologia 110:60-68.

Jorczak, E. 1996. Biological control ofpurple loosetrife in Goodyear Swamp Sanctuary, Otsego County, New York. 29th Ann. Rept. (1996) SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.

Malecki R.L. and T.l Rawinski. 1979. New methods for controlling purple loosetrife. New York Fish and Game Journal. 32:9-19.

Malecki R.A., R Blossey, S.D. Hight, D. Schroeder, L.T. Kok, and lR. Coulson. 1993. Biological control of purple loosetrife. Bioscience 43:680-686.

Rachich J. and R.l Reader. 1999. An experimental study on invasibility by purple loosetrife (Lythrum salicaria). Canadian Journal ofBotany. 77:1499-1503.

Skinner, L. 1996. Biological control ofpurple loosetrife - a new control method for a tough wetland invader. Aquatic Nuisance Species Digest 1(4): 43-45.

Stuckey, R.L. 1980. Distributional history ofLythrum salicaria (purple loosetrife) in North America. Bartonia 47: 3-20.

Thompson D.Q., R.L. Stuckey and E.R Thompson. 1987. Spread, impact and control ofpurple 174

loosetrife in North American wetlands. U.S. Fish and Wildlife Service, Fish and Wildlife Research 2: 1-55.

Welling, C.H. and R.L. Becker. 1990. Seed bank dynamics ofLythrnm salicaria: implications for control of this species in North America. Aquat. Bot. 38:303-309. 175 FORM 1: SITE LOCATION: .' J, Site Name: GOQO"{!::~AP "~:ir\it:\11~ ,li[lNLTVr}l{yOate: >';/O() Town: 'SPRIN(lFI ~LD County: OT5[60 State: NV Longitude: Latitude: GPS Derived? Y N Elevation: '__ Range: __ Twnship: Sect: QtrSect: _

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SITE CHARACTERISTICS: Habitat Type: _River .:7Wetland _Lake _Meadow _Irrigation Ditch _Other

Road Map to Site

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INSECT RELEASE HISTORY'. Date Species Number and Stage Position of Release (mm1dd1vv) (el!I!!larvae/adul0 on MaD 0,2,3.4.. ,) Or;;/04' jq7 aA L'rR' Li(.E, l.,1;ti - SI"Tpc, 1 T'2 CALVit1 Rit h~\S \ ! "00 /?DUl-TS ~" ; (..,\ t '?'\·)~'i\L.\..J'\ , t FORM 2: SPRING QUADRAT SAMPLING: Site Name: ~o r -",;1P, .s \".\j'.MP 5ANCTV",",PY Observer Name(s): ScoT T F~~60HM Date ofObservations: (0 11 20:..') Time: 8=30 Ai"1. Weather: cr.QU()Y !j:"OG- - Temperature: ~7Q"

2.1 - Quadral GaJerucella Hyl Nano Purple Loosestrife Typha spp_ Chart A. Abundance Chan B. Frequency (use Chan A) rn;;:.t~~~i~~.i ~~.~~v"er # rh~,::e A) rh~~eA\ damage ~\e"~" :~~::. ~~:~ Catagories Catagories E L A A A %damage %cover #stems %cover #stems 0 I 0 A 1 :5 I 3 h D 02 A 0 1-9 2 1-5% B fC· 2 .~ I :3 c> 0 6B A 0 10-49 3 5-25% C 3 :j I 2 5: c 63 R I~ 50-99 4 25-50% D 4 L-/ I / ?J 0 7';;­ f3 3 100-499 5 50-75% E 5 1 I Z 13 0 .')~ A 0 500-1000 6 75-100% F 6 >1000 7 7 8 9 10 II

2.2. Purple Loosestrife Typha spp. Height (em) of the 5 tallest plants Height (em) of the 5 tallest olants . Quadrat I 2 3 4 5­ 1 2 3 4 5 I er.s '730.0 77,f.l, 73.0 72 7 - -' ,­ ~ 2 Cj?' l../ 92.3 ;)9.5 7P,,0 7J.C; - - .­ - - 3 /20.0 110.3 I !55 Ie 7.» 1027 /22",'2, IIZS 98.0 c;7,?? 9-71.3 4 CJ9. 'f 9'D.5 ~R.:-3 f0.8 'f-..z.tO f(2,tIJ '38. '"/ 32.S - - 5 '3~. :q ?l,7.S ~.:).3 q.(o 7.5.0 - - - - - 6 7 8 9 10 ...... 2.3. Abundance (check one box) 2.4. Other Observations: -....l Insect species Present ­ r Abundant IVery Abundant 0'1 I,~.\ "H \ PIEPJ" \1'::: '. t'flJ.- \wo(4T<.l~ V

Appendix 2. Form 2 ofBlossey's Galerucella spp. monitoring protocol covering spring sampling data. ~ Site Name: ;oc>\'

2.S. Intlorescmce Quad Purple Loosestri fe Typha spp. Typha spp. Purple Loosestrife # rale % cover (~fart A) rate % cover (Chart Height (em) of the 5 tallest plants Height (em) of the 5 tallest plants ,.nom' n"mfe'r "Ie'm' A \ on.i ,., ,,,n'

2.6. #inflorescences for 5 tallest plants length of tenninal inflor. for 5 tallest plants #flower buds for 5cm of inflorescence total #inflorescences Quadrat I 2 3 4 5 1 2 3 4 5 1 2 3 4 5 per quadrat I - - - ,.-­ - - - - ~ -­ ~ ." " ,~~. ~.- ~- ~ ...... _. _. 2 -­ -­ - .­ - - -­ - 3 i-i P, .1. ?"l 7 41 .30.5 2cr- 30 -75.:;) 2.-7 20 '-f5' 2\ .2.'1 qq ~"::.t 4 /,j­ /0 C; 8 (0 t-Io·O 27 '12,-5 2J1~'" ,32 2.'1 -') ...! 30 7..1-{ 27 ZI'1 5 LI 8 ~~ - - B /0.5 - - /9 /S S .­ ~ /0 6 7 8 9 10

2.7. Quadrats (estimate % cover using chart) 2.8. r Abundance (check one box) 2.9. Other Observations: Present Abun- Very Plant species I 2 3 4 5 6 7 8 9 10 Insect species dapl Abun­ dant J-!evvr::'Y" ~n:: V P.oMF\L.E .RE e: -/ -TA0ANE~E KI.''tn.-.£ .J L A1'1'Y K~)(;-" -/

.....:l .....:l Appendix 3. Fonn 2 ofBlossey's Galerucella spp. monitoring protocol covering fall sampling data. P> _ - ~('> ~ ~t:l z ~ o...., aP> ,.;;;..~ 5f~w ~ C\) •• ~8t'"' §;-(r:J:J=. 0 ­ ~$~ '0 ~ .o..~~0 ~ C)_l> ()vz ~J~~r~,~ f\~ r:J:J ~ "'tl Ktz~rzr

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Appendix 4. Form 3 ofBlossey's Galerucella spp. monitoring protocol covering native flora present in established plots. (Note: this data includes % coverage estimations that -..l were to be included in the fall sampling observations on Form 2, but due to the species 00 diversity it was necessary to list the % coverage on Form 3.)