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Predic'ng 
the 
Distribu'on 
of 
the 
Invasive 
Cactus 
Moth, 
Cactoblas)s 
cactorum, 
and 
its 
Major 
Host 
Plant, 
Opun...
Florida 
Opun)a 
and 
Their 
Specialist 
Insect 
Herbivores 
Invasive 
Cactus 
Moth, 
Cactoblas)s 
cactorum 
Na've 
Cactus...
The 
invasive 
cactus 
moth, 
Cactoblas)s 
cactorum, 
“blas'ng” 
its 
host 
species, 
Opun)a 
stricta, 
in 
Florida
Background 
• Opun%a 
are 
na&ve 
to 
the 
New 
World 
(North 
and 
South 
America) 
• Including 
the 
phylogeny 
and 
“pu...
The 
Path 
to 
the 
North 
American 
Introduc'on 
First 
introduced 
into 
Australia 
to 
control 
invasive 
cac& 
1957 
E...
Successful 
Biological 
Control 
in 
Australia 
Before… 
ARer. 
“In 
August 
1930, 
for 
150 
miles 
[240 
km] 
along 
the...
Distribu'on 
of 
the 
Invasive 
Cactus 
Moth 
in 
the 
Louisiana, 
2009 
Most 
recent 
detec&ons: 
Jefferson, 
Lafourche, ...
Ques'ons 
• How 
prevalent 
is 
the 
invasive 
cactus 
moth 
and 
moth 
damage? 
• How 
important 
are 
different 
factors...
The 
invasive 
moth 
is 
found 
primarily 
on 
O. 
humifusa 
var. 
ammophila 
and 
O. 
stricta 
(Sauby 
et 
al. 
2012)
Sampling 
at 
the 
Guana 
Tolomato 
Matanzas 
Na'onal 
Estuarine 
Research 
Reserve 
(GTMNERR) 
• Plot 
Surveys 
• Plant 
...
• Set 
Sampling 
Scheme 
– 
Plot 
Surveys 
up 
1-­‐meter2 
plots 
according 
to 
a 
stra&fied 
random 
adap&ve 
cluster 
s...
• Set 
Sampling 
Scheme 
– 
Plot 
Surveys 
up 
1-­‐meter2 
plots 
according 
to 
a 
stra&fied 
random 
adap&ve 
cluster 
s...
• Set 
Sampling 
Scheme 
– 
Plot 
Surveys 
up 
1-­‐meter2 
plots 
according 
to 
a 
stra&fied 
random 
adap&ve 
cluster 
s...
Sampling 
Scheme 
– 
Plant 
Surveys 
• Mapped 
and 
marked 
individual 
cactus 
plants 
in 
a 
random 
subset 
of 
plots 
...
Prevalence 
of 
Cac' 
in 
SRSWOR 
Plots 
• Propor&on 
of 
area 
occupied 
by 
each 
cactus 
species 
• O. 
humifusa 
var. ...
Sample 
Size 
of 
Plots 
with 
Cac' 
aRer 
Adap've 
Cluster 
Sampling 
• Increased 
the 
number 
of 
plots 
with 
cac& 
11...
400 
350 
300 
250 
200 
150 
100 
50 
Prevalence 
of 
the 
Invasive 
Cactus 
Moth 
Aggregated 
Plot 
Survey 
Data 
(May 
...
400 
350 
300 
250 
200 
150 
100 
50 
Prevalence 
of 
the 
Invasive 
Cactus 
Moth 
Moth 
Absent 
Moth 
Present 
Number of...
Prevalence 
of 
Damage 
from 
Past 
Moth 
Infesta'ons 
O. pusilla 
54/449 
= 
12% 
350 
300 
250 
200 
150 
100 
50 
Damag...
Hypothesized 
Dynamics 
of 
Cactus 
Moth 
Invasion 
N 
cac& 
t 
invasive 
cactus 
moth 
Current 
state 
of 
invasion
Generalized 
Linear 
Mixed 
Models 
to 
Explain 
Paherns 
of 
O. 
stricta 
Occurrence 
Analyzed 
in 
SAS 
v. 
9.4 
using 
...
Results 
-­‐ 
Generalized 
Linear 
Mixed 
Models 
to 
Explain 
Paherns 
of 
Cactus 
Occurrence 
Tests 
of 
Fixed 
Effects ...
Results 
– 
Rela'onship 
Between 
Vegeta'on 
Class 
and 
O. 
stricta 
Occurrence 
Least 
Squares 
Means 
Vegeta'on 
Class ...
Generalized 
Linear 
Mixed 
Model 
to 
Explain 
Paherns 
of 
Invasive 
Cactus 
Moth 
Occurrence 
on 
O. 
stricta 
• Limite...
Results 
-­‐ 
Generalized 
Linear 
Mixed 
Model 
to 
Explain 
Paherns 
of 
Invasive 
Cactus 
Moth 
Occurrence 
on 
O. 
str...
Conclusions 
• Abio&c 
and 
bio&c 
factors 
can 
be 
used 
to 
explain 
pa`erns 
of 
cactus 
and 
cactus 
moth 
occurrence...
Conclusions 
Invasive 
cactus 
moth 
occurrence 
• Cumula&ve 
damage 
is 
much 
greater 
than 
present 
rates 
of 
infesta...
Invasive 
Species 
Management 
• Important 
to 
consider 
the 
rela&ve 
threat 
of 
the 
species 
• Important 
to 
account...
Future 
Work 
• Assess 
temporal 
and 
spa&al 
autocorrela&on 
in: 
– the 
dynamics 
of 
cactus 
and 
cactus 
moth 
occupa...
Acknowledgments 
University 
of 
Florida 
• Michael 
Barfield 
• James 
Nifong 
• Doria 
Gordon 
• Robert 
Fletcher 
• Jos...
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Predicting the Distribution of the Invasive Cactus Moth, Cactoblastis cactorum, and its Major Host Plant, Opuntia stricta, in Florida

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A presentation at the Ecological Society of America Annual Meeting on August 11, 2014 in Sacramento, California.

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Predicting the Distribution of the Invasive Cactus Moth, Cactoblastis cactorum, and its Major Host Plant, Opuntia stricta, in Florida

  1. 1. Predic'ng the Distribu'on of the Invasive Cactus Moth, Cactoblas)s cactorum, and its Major Host Plant, Opun)a stricta, in Florida Kristen E. Sauby, Mary C. Christman, and Robert D. Holt Department of Biology University of Florida Ecological Society of America Annual Mee'ng Sacramento, California August 11, 2014
  2. 2. Florida Opun)a and Their Specialist Insect Herbivores Invasive Cactus Moth, Cactoblas)s cactorum Na've Cactus Moth, Melitara prodenialis Na've Cactus Bug, Chelinidea vi7ger Na've Cactus Scale, Dactylopius sp. O. stricta O. pusilla O. humifusa var. ammophila
  3. 3. The invasive cactus moth, Cactoblas)s cactorum, “blas'ng” its host species, Opun)a stricta, in Florida
  4. 4. Background • Opun%a are na&ve to the New World (North and South America) • Including the phylogeny and “puta&ve dispersal pathways of Opun%a clades” (Majure et al., American Journal of Botany, 2012)
  5. 5. The Path to the North American Introduc'on First introduced into Australia to control invasive cac& 1957 Early 1930s 1925 of the Invasive Cactus Moth Approx. na&ve range of moth
  6. 6. Successful Biological Control in Australia Before… ARer. “In August 1930, for 150 miles [240 km] along the river the pest [O. stricta] was in its full vigour, its con&nuity almost unbroken by cleared land; the pastoral proper&es had been overrun and mainly deserted.” • Quotes from Dodd (1940) • Photos from Osmond et al. “…in August 1932, 90 percent of the [prickly] pear had collapsed. The change in exactly two years was extraordinary.” 2008 (Journal of Experimental Botany)
  7. 7. Distribu'on of the Invasive Cactus Moth in the Louisiana, 2009 Most recent detec&ons: Jefferson, Lafourche, and Terrebonne Parishes, Louisiana (2009) Southeastern United States South Carolina, 2004 First detec'on, Florida Keys, 1989 Source: USDA APHIS, h`p://www.aphis.usda.gov/plant_health/plant_pest_info/cactoblas&s/spread.shtml, accessed 21 March 2009 NE Florida, 2000
  8. 8. Ques'ons • How prevalent is the invasive cactus moth and moth damage? • How important are different factors in structuring varia&on in cactus and invasive cactus moth occurrence? – Abio&c factors (eleva&on) – Bio&c factors (plant density, canopy cover) – Spa&al factors
  9. 9. The invasive moth is found primarily on O. humifusa var. ammophila and O. stricta (Sauby et al. 2012)
  10. 10. Sampling at the Guana Tolomato Matanzas Na'onal Estuarine Research Reserve (GTMNERR) • Plot Surveys • Plant Surveys
  11. 11. • Set Sampling Scheme – Plot Surveys up 1-­‐meter2 plots according to a stra&fied random adap&ve cluster sampling scheme 1. Stra&fied Random Sampling (SRSWOR): plots randomly distributed across (a) 5 islands and (b) two habitat patches (524 plots) 2. Adap&ve Cluster Sampling: If a plot had cac&, adjacent plots were also surveyed (c) (829 plots) • Surveyed plots at least twice a year (May 2012 – present) • Then aggregated data for analysis
  12. 12. • Set Sampling Scheme – Plot Surveys up 1-­‐meter2 plots according to a stra&fied random adap&ve cluster sampling scheme 1. Stra&fied Random Sampling (SRSWOR): plots randomly distributed across (a) 5 islands and (b) two habitat patches (524 plots) 2. Adap&ve Cluster Sampling: If a plot had cac&, adjacent plots were also surveyed (c) (829 plots) • Surveyed plots at least twice a year (May 2012 – present) • Then aggregated data for analysis (c)
  13. 13. • Set Sampling Scheme – Plot Surveys up 1-­‐meter2 plots according to a stra&fied random adap&ve cluster sampling scheme 1. Stra&fied Random Sampling (SRSWOR): plots randomly distributed across (a) 5 islands and (b) two habitat patches (523 plots) 2. Adap&ve Cluster Sampling: If a plot had cac&, adjacent plots were also surveyed (c) (824 plots) • Surveyed plots at least twice a year (May 2012 – present) • Aggregated data for analysis (c)
  14. 14. Sampling Scheme – Plant Surveys • Mapped and marked individual cactus plants in a random subset of plots (287 plots; 1089 O. stricta and 1087 O. pusilla plants) • Surveyed all at least twice a year (Jan. 2013 – present) • Aggregated data for analysis
  15. 15. Prevalence of Cac' in SRSWOR Plots • Propor&on of area occupied by each cactus species • O. humifusa var. ammophila was rare (found in only 1 plot) 500 400 300 200 100 Absent Present Number of plots O. stricta 500 400 300 200 100 O. pusilla Absent Present 75/523 = 14.3% 45/523 = 8.6%
  16. 16. Sample Size of Plots with Cac' aRer Adap've Cluster Sampling • Increased the number of plots with cac& 1100 1000 900 800 700 600 500 400 300 200 100 Absent Present Number of plots O. stricta 1100 1000 900 800 700 600 500 400 300 200 100 O. pusilla Absent Present 447/1347 = 33.2% 324/1347 = 24.1%
  17. 17. 400 350 300 250 200 150 100 50 Prevalence of the Invasive Cactus Moth Aggregated Plot Survey Data (May 2012 – present) Moth Absent Moth Present Number of plots O. stricta 400 350 300 250 200 150 100 50 O. pusilla Moth Absent Moth Present 54/447 = 12.1% 1/324 = 0.31% Presence = moth larvae and/or eggs were found at least once Absence = moth larvae and/or eggs never observed
  18. 18. 400 350 300 250 200 150 100 50 Prevalence of the Invasive Cactus Moth Moth Absent Moth Present Number of plots O. stricta 400 350 300 250 200 150 100 50 O. pusilla Moth Absent Moth Present 1100 1000 900 800 700 600 500 400 300 200 100 Moth Absent Moth Present Number of plants O. stricta 35/1089 = 3.2% Aggregated Plot Survey Data (May 2012 – present) Aggregated Plant Survey Data (January 2013 – present) 54/447 = 12.1% 1/324 = 0.31% Presence = moth larvae and/or eggs were found at least once Absence = moth larvae and/or eggs never observed
  19. 19. Prevalence of Damage from Past Moth Infesta'ons O. pusilla 54/449 = 12% 350 300 250 200 150 100 50 Damage Absent Damage Present Number of plots O. stricta 350 300 250 200 150 100 50 Damage Absent 122/324 = 38% Damage Present 334/447 = 75% • An es&mate of cumula&ve prevalence of cactus moths • Many plants are infested at some point in their lives • Es&mates may be biased low because only live plants are surveyed • Caveat: damage may be from either the invasive and/or na&ve cactus moths
  20. 20. Hypothesized Dynamics of Cactus Moth Invasion N cac& t invasive cactus moth Current state of invasion
  21. 21. Generalized Linear Mixed Models to Explain Paherns of O. stricta Occurrence Analyzed in SAS v. 9.4 using GLIMMIX procedure Dependent Variables • O. stricta presence Fixed Effects • Eleva&on (meters) • Vegeta&on Class (five categories) • Vegeta&on Density (scale of 0 – 4) • Detritus Density (scale of 0 – 4) • Canopy (yes/no) Random Effects • Habitat Patch • Network (the adap&ve cluster to which a plot belongs)
  22. 22. Results -­‐ Generalized Linear Mixed Models to Explain Paherns of Cactus Occurrence Tests of Fixed Effects Effect Es'mate St. Error Pr > F Canopy 0.17 0.33 0.5970 Vegeta&on Class -­‐ -­‐ 0.0007 Vegeta&on Density 0.38 0.12 0.0010 Detritus Density 0.42 0.11 <.0001 Eleva&on (m) 0.037 0.10 0.7153
  23. 23. Results – Rela'onship Between Vegeta'on Class and O. stricta Occurrence Least Squares Means Vegeta'on Class Mean Prob(Y=1) Standard Error t Value Pr > |t| Marsh plants 0.0097 0.0081 -­‐5.50 <.0001 Mixed forbs 0.16 0.059 -­‐3.78 0.0002 Overhanging cedar/mixed forbs 0.14 0.057 -­‐3.83 0.0001 Palm/palme`o 0.00014 0.0022 -­‐0.57 0.57 Shrubs/vines 0.083 0.039 -­‐4.64 <.0001
  24. 24. Generalized Linear Mixed Model to Explain Paherns of Invasive Cactus Moth Occurrence on O. stricta • Limited analysis to plots containing O. stricta • Analyzed in SAS v. 9.4 using GLIMMIX procedure Dependent Variable • Invasive Cactus Moth presence Fixed Effects • O. stricta maximum height • O. stricta percent cover • Eleva&on (meters) • Vegeta&on Class (seven categories) • Vegeta&on Density (scale of 0 – 4) • Detritus Density (scale of 0 – 4) • Canopy (yes/no) Random Effects • Network (the adap&ve cluster to which a plot belongs) • Did NOT include Habitat Patch because it was not sta&s&cally significant in a model with only random effects
  25. 25. Results -­‐ Generalized Linear Mixed Model to Explain Paherns of Invasive Cactus Moth Occurrence on O. stricta Effect Es'mate St. Error Pr > F Canopy 0.21 0.7751 0.79 Vegeta'on Class -­‐ -­‐ 0.52 O. stricta Height 0.042 0.016 0.011 O. stricta Percent Cover 0.038 0.018 0.037 Eleva'on 0.23 0.094 0.013 Detritus 0.046 0.22 0.84
  26. 26. Conclusions • Abio&c and bio&c factors can be used to explain pa`erns of cactus and cactus moth occurrence O. stricta occurrence • Posi&ve rela&onship with detritus and vegeta&on density • Significant varia&on among vegeta&on classes
  27. 27. Conclusions Invasive cactus moth occurrence • Cumula&ve damage is much greater than present rates of infesta&on • Rare on O. pusilla • Posi&vely related to O. stricta height and percent cover as well as eleva&on Spa&al factors • Habitat patch and Network included in models of cactus occurrence as random effects
  28. 28. Invasive Species Management • Important to consider the rela&ve threat of the species • Important to account for spa&al varia&on in risk of invasion and costs of surveillance (Epanchin-­‐Niell et al., Ecol. Le;., 2012)
  29. 29. Future Work • Assess temporal and spa&al autocorrela&on in: – the dynamics of cactus and cactus moth occupancy • Assess threat of the invasive cactus moth to cac& using demographic models
  30. 30. Acknowledgments University of Florida • Michael Barfield • James Nifong • Doria Gordon • Robert Fletcher • Jose Miguel Poncianco • Jake Ferguson • Rosana Zenil-­‐Ferguson • Polly Harding (pictured) Feel free to contact me at ksauby@ufl.edu GTMNERR • Ka'e Petrinec • Mah Welsh

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