We explored the joint effects of native and invasive insect herbivory on plant population growth using a set of closely interacting species: two species of native cacti (Opuntia) in Florida and two cactus moth species (the native Melitara prodenialis and the invasive South American Cactoblastis cactorum).

1. The$popula*on,level$
consequences$of$na*ve$and$
invasive$herbivores$for$na*ve$
cac*$in$Florida$
Kristen(E.(Sauby,(Mary(C.(Christman(and(
Robert(D.(Holt(
Department(of(Biology,((
University(of(Florida(
Ecological(Society(of(America(
Fort(Lauderdale,(Florida(
August(8,(2016(

2. IntroducKon(
• What(is(the(impact(of(an(invasive(insect(to(its(
naKve(host(plants?(
– Host(plant(vital(rates(
– negaKve(effects(on(vital(rates(do(not(necessarily(
translate(into(a(negaKve(effect(on(populaKon(size(
or(trends(
– thus(it(is(difficult(to(infer(the(consequences(of(
species(interacKons(to(plant(populaKon(dynamics(

3. IntroducKon(
• What(is(the(impact(of(an(invasive(insect(to(its(
naKve(host(plants?(
– Host(plant(vital(rates(
– negaKve(effects(on(vital(rates(do(not(necessarily(
translate(into(a(negaKve(effect(on(populaKon(size(
or(trends(
– thus(it(is(difficult(to(infer(the(consequences(of(
species(interacKons(to(plant(populaKon(dynamics(

4. QuesKons(
• What(is(the(impact(of(an(invasive(insect(to(
naKve(host(plant(vital(rates?(
• What(is(the(impact(of(an(invasive(insect(to(
naKve(host(plant(populaKon(dynamics((i.e.,(
asymptoKc(populaKon(growth(rate)?(

5. Florida$Opun%a'and$Their$Specialist$Insect$Herbivores'

6. Florida$Opun%a'and$Their$Specialist$Insect$Herbivores'

7. The$invasive$cactus$moth,$
Cactoblas%s'cactorum,'
“blas*ng”$its$host$species,$
Opun%a'stricta,'in$Florida'

8. The$Path$to$the$North$American$
Introduc*on$of$C.'cactorum$
1925(

9. Successful$Biological$Control$in$Australia$
Before…$ AFer.$
Photos(from(Osmond(et&al.&2008&(Journal(of(Experimental(Botany)(

10. 1957(
Early(
1930s(
1925(
The$Path$to$the$North$American$
Introduc*on$of$C.'cactorum$

11. Source:(USDA(APHIS,(
h_p://www.aphis.usda.gov/plant_health/plant_pest_info/cactoblasKs/spread.shtml,((((((((
accessed(21(March(2009(
Most(recent(
detecKons:(Jefferson,(
Lafourche,(and(
Terrebonne(Parishes,(
Louisiana((2009)(
Distribu*on$of$the$Invasive$Cactus$Moth$in$the$
Southeastern$United$States$
South$Carolina,$2004$
Louisiana,$2009$
First$detec*on,$
Florida$Keys,$1989$
2000$2003$ 2002$

12. Sampling(at(the(Guana(Tolomato(Matanzas(NaKonal(
Estuarine(Research(Reserve((GTMNERR)(
Big Lagoon SP
No
Henders
MARINELAND
SAINT AUGUSTINE
00 5 10 15 202.5
Kilometers
ST. JOHNS
COUNTY
FLAGLER
COUNTY
0 0.50.25
(a)

13. Plot(Surveys(Across(7(Habitat(Patches(
(• 447(1fmeter2(plots(
• Each(plot(was(surveyed(twice(a(year(from(May(2013(–(August(2015(
• Measured(plant(size(and(reproducKve(output(Spring/Summer(
• Recorded(insect/presence(absence,(recruitment(in(Spring/Summer(and(Fall/Winter(
• Number(of(individuals(surveyed(at(start(:(886((Spring/Summer(2013)(
• Number(of(individuals(surveyed(in(total:(1369((483(recruits)(
400 0 400200 Meters
660 0 660330 Meters 0.6 0 0.60.3 Kilometers
0 0.3 0.6 0.9 1.20.15
Kilometers
0 0.5 10.25 Kilometers
0 350 700175 Meters
(a)
(b)

14. Hypotheses(
• The(invasive(moth(will(negaKvely(affect(vital(
rates(and(the(asymptoKc(populaKon(growth(
rate,(λ,(of(Opun-a&stricta(
• The(naKve(moth(will(have(no(effect(on(vital(
rates(and(λ(

15. Objec*ves$
• Examine(relaKonship(between(moth(presence(
and(vital(rates(
– Growth(
– Sexual(ReproducKon(
– Survival(
• Construct(and(analyze(matrix(populaKon(
model(to(determine(effect(of(moth(presence(
on(asymptoKc(populaKon(growth(rate,(λ(
– ElasKcity(analysis(

16. Rela*ve$Growth$Rate$
RGR = 365×(!"#$!!! − !"#$!)/(!×!"#$!)
d(=(days(between(survey(at(Kme&t&and(Kme(t+1&

17. Growth$
Linear(mixed(model(in(SAS/STAT(version(13.2((
0
10
20
30
0 1 2 3 4 5
ln(Sizet)
AnnualRelativeGrowthRate
Invasive Moth Present During Study? Yes No
• Overall,(negaKve(relaKonship(between(size(and(RGR(
• Significant((small)(posiKve(effect(of(the(invasive(moth(

18. 0
10
20
30
0 1 2 3 4 5
ln(Sizet)
AnnualRelativeGrowthRate
Native Moth Present During Study? Yes No
Growth$
Linear(mixed(model(in(SAS/STAT(version(13.2((
• Significant((small)(posiKve(effect(of(the(naKve(moth(

19. 0
10
20
30
0 1 2 3 4 5
ln(Sizet)
AnnualRelativeGrowthRate
Native Moth Present During Study? Yes No
Growth$
Linear(mixed(model(in(SAS/STAT(version(13.2((
• Significant((small)(posiKve(effect(of(the(naKve(moth(

20. Sexual$Reproduc*on$
• No(effect(on(fruit(presence(
• PosiKvely(associated(with(
higher(fruit(count(
(
• Found(on(only(one(plant(
with(fruit(
0
1
2
3
4
No Yes
Invasive Moth Present
During Study?
ln(NumberofFlowersandFruit)
Invasive$Moth$
Na*ve$Moth$
Zerofinflated(Poisson(model((SAS/STAT(version(13.2)((

21. Survival$
Study(length(=(1000(days((2012f12f02(to(2015f08f29)(
Cox(proporKonal(hazards(regression((SAS/STAT(version(13.2)((
Follow Up Time (Days)
0 100 200 300 400 500 600 700 800 900 1000
SurvivalProbability
0.00.20.40.60.81.0
Invasive Moth Absent
Invasive
Moth
Present
Higher(for(plants(infested(by(the(invasive(moth(during(
the(study(

22. Posi*ve$Rela*onship$Between$Survival$and$
Invasive$Moth$Presence$During$the$Study$
Due(to(the(invasive(moth’s(a_racKon(to(larger(plants?(
0
1
2
3
4
5
No Yes
Invasive Moth Present
at Time t?
ln(Sizet)

23. Posi*ve$Rela*onship$Between$Survival$and$
Invasive$Moth$Presence$During$the$Study$
Due(to(the(invasive(moth’s(a_racKon(to(larger(plants?(
0
1
2
3
4
5
Island 1 Island 2 Island 3 Island 4 Island 5 Coastal
Grassland
Beach
Dunes
Habitat Patch
ln(Sizet)
Invasive Moth Present at Time t? No Yes
0
1
2
3
4
5
No Yes
Invasive Moth Present
at Time t?
ln(Sizet)

24. Follow Up Time (Days)
0 100 200 300 400 500 600 700 800 900 1000
SurvivalProbability
0.00.20.40.60.81.0
Native Moth Absent
Native
Moth
Present
Survival$
Study(length(=(1000(days((2012f12f02(to(2015f08f29)(
Cox(proporKonal(hazards(regression((SAS/STAT(version(13.2)((
No(effect(of(naKve(moth(presence(during(the(study(

25. What(are(the(consequences(of(invasive(
moth(infestaKon(for(the(asymptoKc(
populaKon(growth(rate,(λ?(
• Construct(Matrix(PopulaKon(Models(
• Determine(which(vital(rates(are(most(
important(to(the(populaKon(growth(rate(
– With(elasKcity(analyses(

26. Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Recruitment$
Seed(Seedling(
Stasis$
Note:(
• TransiKons(are(based(on(data(except(
• seed$recruitment$rate:(based(on(previous(studies(
• Number$of$seeds$produced$per$plant:((
• Average(#(of(seeds(per(fruit((observed(from(40(fruit)(x(
observed(number(of(fruit(
• Time(step(is(1(year(
• Data(represents(transiKons(from(2013(to(2014(

27. Seed(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Growth$
(1$year)$
Seedling(Juvenile(
(1(segment)(

28. Seedling( Seed(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Juvenile(
(1(segment)(
Stasis$

29. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Sexual$Reproduc*on$
Growth$
Growth$
1(
segment(
Stasis$

30. Stage(7(
(10+(
segments)(
Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Clonal$Reproduc*on$+$$
Retrogression$
Growth$
Stasis$
Growth$
2(
segments(

31. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Clonal$Reproduc*on$+$$
Retrogression$
Growth$
Growth$
Stasis$
Clonal$
Reproduc*on$+$$
Retrogression$
3(
segments(

32. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Stasis$
Growth$
Clonal$Reproduc*on$+$$
Retrogression$
Clonal$Reproduc*on$+$$
Retrogression$
Retrogression$
4(
segments(

33. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(
Retrogression$
Stasis$
Growth$
Clonal$Reproduc*on$+$$
Retrogression$
Retrogression$
5(
segments(

34. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(7(
(10+(
segments)(
Stasis$
Growth$
Clonal$Reproduc*on$+$$Retrogression$
Retrogression$
Sexual$Reproduc*on$
Stage(6(
(6f9(
segments)(

35. Seedling( Seed(
Juvenile(
(1(segment)(
Life$Cycle$Diagram$for$Opun%a'stricta'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
Stage(6(
(6f9(
segments)(
Stasis$
Clonal$Reproduc*on$
Clonal$Reproduc*on$
Retrogression$
Retrogression$
Sexual$
Reproduc*on$
Stage(7(
(10+(
segments)(

36. Seedling( Seed(
Juvenile(
(1(segment)(
Important$Transi*ons$According$to$Elas*city$Analysis'
1(
segment(
2(
segments(
4(
segments(
3(
segments(
5(
segments(
0.14$
Note:(
• All(2013f2014(transiKon(data(
• StarKng(values(
• 1000(seeds(
• 100(individuals(all(other(stages(
0.15$
0.06$
Stage(7(
(10+(
segments)(
Stage(6(
(6f9(
segments)(

37. Popula*on$Dynamics$Based$on$
2013,2014$Transi*on$Data$
Model$ λ$ Number$of$Unique$Individuals$
EnKre(Dataset( 0.988( 778(
Divide(dataset(based(on(invasive(moth(presence(
With(Invasive(Moth( 0.982( 664(
Without(Invasive(Moth( 1.45( 114(
Divide(dataset(based(on(invasive(moth(presence(
With(NaKve(Moth( 1.098( 397(
Without(NaKve(Moth( 1.001( 381(
• For(dataset(without(invasive(moth(
• no(seedling(recruitment(observed;(set(to(0.001(
• Seedling(to(juvenile(set(to(1(

38. Plots(with(cacK(
sampled(in(clusters(
Yellow:(CacK(absent$
Green:(CacK(present(

39. Popula*on$Dynamics$Based$on$
2013,2014$Transi*on$Data$
Model$ λ$ Number$of$Unique$Individuals$
EnKre(Dataset( 0.988( 778(
Divide(dataset(based(on(invasive(moth(presence(
With(Invasive(Moth( 0.982( 664(
Without(Invasive(Moth( 1.45( 114(
Divide(dataset(based(on(invasive(moth(presence(
With(NaKve(Moth( 1.098( 397(
Without(NaKve(Moth( 1.001( 381(
• For(dataset(without(invasive(moth(
• no(seedling(recruitment(observed;(set(to(0.001(
• Seedling(to(juvenile(set(to(1(

40. Popula*on$Dynamics$Based$on$
2013,2014$Transi*on$Data$
Model$ λ$ Number$of$Unique$Individuals$
EnKre(Dataset( 0.988( 778(
Divide(dataset(based(on(invasive(moth(presence(
With(Invasive(Moth( 0.982( 664(
Without(Invasive(Moth( 1.45( 114(
Divide(dataset(based(on(invasive(moth(presence(
With(NaKve(Moth( 1.098( 397(
Without(NaKve(Moth( 1.001( 381(
• For(dataset(without(invasive(moth(
• no(seedling(recruitment(observed;(set(to(0.001(
• Seedling(to(juvenile(set(to(1(

41. Conclusions$
• Impact(of(invasive(but(not(naKve(moth(to(
cactus(vital(rates(
• PopulaKon(models(suggest(that(the(invasive(
may(negaKvely(impact(the(populaKon(growth(
rate(
– Also(suggests(no(effect(of(naKve(moth(

42. Future(Work(
• Run(simulaKons(with(2013f2014(and(
2014f2015(transiKon(data(to(incorporate(
– Demographic(stochasKcity(
– SpaKal(variaKon((among(the(7(habitat(patches)(
• Sufficient(data(for(Life(Table(Response(
Experiments?(
• Increase(sample(size(of(large(plants?(

43. Acknowledgments$
• University$of$Florida$
• James(Nifong(
• Polly(Harding(
• GTMNERR$
• KaKe(Petrinec(
• Ma_(Welsh(
Funding$
• Carrie(Lynn(Yoder(Scholarship(for(Plant(Ecology(and(
ConservaKon(Research(in(Florida(
• Florida(NaKve(Plant(Society(
• Botanical(Society(of(America(
• QuanKtaKve(SpaKal(Ecology,(EvoluKon,(and(Environment(
(QSE3)(IGERT(
• Garden(Club(of(America(and(Center(for(Plant(ConservaKon(
• Cactus(and(Succulent(Society(of(America(
• Graduate(Student(Council,(University(of(Florida(
• Department(of(Biology,(University(of(Florida(