Cristiana Cerrato

Larval ecology of Colias palaeno in the N-W Italian Alps

Turin University - Life Sciences and Systems Biology Department

Future of Butterflies in Europe III – 29-31 March 2012

• 189 extant populations

• 7 became extinct

(time frame ‘before 1950’, 4 ‘unknown’ vs 3 habitat)

• oligotrophic

• acidic soil

• low temperature

• between 1700 – 2300 m

• flight period July-August

Balletto et al. 2007 Peat bogs

Alpine - heaths

Colias palaeno in Italy

Describe the role of biotic and abiotic parameters at a spatial and temporal scale relevant for the caterpillars

Micro-habitat

Micro-climate

Larval host plant condition

Objectives

Survival

Knowledge of the larval needs by target species may be crucial to desing adequate management practice Habitat quality is often defined on the basis of the requirements of the immature stages, because they are more specific than those of the adults This is due to the low or absent mobility as well as the longer life time of the immature stages e.g. Thomas JA (1991) Rare species conservation: case studies of European butterflies. In: Spellerberg IF, Goldsmith FB, Morris MG (eds) The scientific management of temperate communities for conservation. Blackwell Scientific, Oxford, pp 149–197

Micro-climate Micro-climatic cooling linked to nitrogen deposition and global warming by advancing plant growth Optimal temperature and humidity level Wallisdevries and van Swaay (2006) Global waming and excess nitrogen may induce butterfly decline by microclimatic cooling – Global Change Biology 12: 1620-1626

Physical characteristics of the larval host plant Bigger leaves and/or bigger plants Linkage to micro-climate Zalucki, Clarke and Malcom (2002) Ecology and behaviour of first instar larvae - Annual Revue of Entomology 47: 361-393

Influencial factors

Throop and Lerdau (2004) – Effects of nitrogen deposition on insect herbivory: Implications for community and ecosystem processes – Ecosystems 7: 109-133 Fisher and Fiedler, (2000): Response of the copper butterfly Lycaena tityrus to increased leaf nitrogen in natural food plants: evidence against the nitrogen limitation Hypothesis – Oecologia 124: 235-241 Stiling and Cornelissen (2007) – How does elevated carbon-dioxide (CO2) affect plant-herbivore interactions? – Global Change Biology 13: 1823-1842

Chemical characteristics of the larval host plant Nitrogen Carbon-based secondary metabolites

Phenological asynchrony Different responses of different trophic levels Insect phenology must ensure the temporal match of larvae and larval resources Monovoltine species have a narrow window of opportunity to exploit resources Singer and Parmesan (2010) Phenological asynchrony between herbivorous insects and their hosts: signal of climate change or pre-existing adaptive strategy? – Phil Trans Royal Society

Influencial factors

• 18 study areas in 2 valleys

Val Formazza and Val Bognanco

• Altitudinal gradient

1600-2300 m a.s.l.

• Dry vs Wet sites

• Sistematically searched for eggs/instars

3 times during the season / 2 hours for visit

Characterized in term of LHP

Random squares 1x1 m (15% minimum coverage by Vaccinium

uliginosum) -Vegetation structure - Height of herbaceous and

shrubs layer - LHP description (height, spring growth, number of

leaves, lenght and widht of the apical leaf)

Where is Colias palaeno in the Alps - Sampling design

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

Density (n / 100 m2)

104 caterpillars in 14 study areas

1. Most sites were occupied (14 vs 4)

2. Low densities

Low altitude and high canopy closure

Where is Colias palaeno the Alps?

dry humid

occupied 4 10

not occupied 3 1

Name: Balma Habitat: Peat bog Altitude: 2000 m Dimension: 1.6 ha Number of pre-immaginal stages: 100

Name: Erioforo Habitat: Humid area Altitude: 2000 m Dimension: 1.2 ha Number of pre-immaginal stages: 90

Larval survival - Study areas

Name: Curzalma Habitat: Alpine heathland Altitude: 2300 m Dimension: 0.3 ha Number of pre-immaginal stages: 80

Name: Arpa Habitat: Alpine heathland Altitude: 1900 m Dimension: 0.5 ha Number of pre-immaginal stages: 170

Larval survival - Study areas

Micro-climate Data-logger Micro-habitat structure

Life-history traits Every 5-7 days Survival classes

Growth rate (length) Feeding rate

Larval Host Plant Spatial and temporal sampling Mid August

Mid September 10 sampling points per site in Italy

N s

pe

cim

ens

Egg

Larval survival - Sampling methods

Mean

±SE

±SD

Outl iersarpa balma curzalma erioforo

Study area

7

8

9

10

11

12

13

14

Poly

phenol conte

nt

Polyphenol: KW-H(3,40) = 11.716, p = 0.008

Lower survival rate:

- Higher level of polyphenols and tannins

- Higher level of secondary metabolites/nitrogen ratio

- No differences in primary metabolisms among sites

Larval survival - Main results

Habitat Altitude Egg - I I - II II - III Total

Heathland 1900 m 58.6 63.9 54.4 20.4

Humid area 2000 m 44.9 63.2 48.6 13.8

Peat Bog 2000 m 55.0 60.0 39.5 13.0

Heathland 2300 m 48.0 45.5 32.0 7.0

Larval survival - Main results

To avoid temporal autocorrelation, we used a

subsample of sampling period (2/8 - 5/10): every 3 days

mesurements (r <0.5)

Mean temperature (°C) - 16 cm

Mean

±SE

±1.96*SE

Media

di t_

arp

a16

Media

di t_

balm

a16

Media

di t_

curz

16

Media

di t_

eri16

6

7

8

9

10

11

12

13

Hea

thla

nd

– 1

90

0 m

Peat

bo

g –

20

00

m

Hea

thla

nd

– 2

30

0 m

Hu

mid

are

a –

23

00

m

Friedman ANOVA test, N = 22, df = 3, χ2 = 53.073, p < 0.0001

Habitat Altitude Egg - I I - II II - III Total

Heathland 1900 m 58.6 63.9 54.4 20.4

Humid area 2000 m 44.9 63.2 48.6 13.8

Peat Bog 2000 m 55.0 60.0 39.5 13.0

Heathland 2300 m 48.0 45.5 32.0 7.0

- Higher survival rate: higher near-ground

temperatures

Mean

±SE

±1.96*SE

Outl iers

0 18

10

12

14

16

18

20

22

Litte

r covera

ge (

%)

Dead Survived

Egg - first instar: site and vegetation structure

Parameters Estimate Standard Wald p

Interc 0.516 0.557 0.859 0.354

litter coverage 0.034 0.013 6.598 0.010

shrubs -0.013 0.007 3.910 0.048

Area: heathland (1900 m) 0.636 0.193 10.799 0.001

N dead = 165 N survived = 187

Variable Dead Survived

Litter coverage (%) 11.3 (0.8) 14.2 (0.9)

Mean

±SE

±1.96*SE

Outl iers

0 11.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

Tre

ndP

ol

First - second instar: secondary metabolites

Mean

±SE

±1.96*SE

Outl iers

0 111.0

11.2

11.4

11.6

11.8

12.0

12.2

12.4

12.6

12.8

13.0

13.2

13.4

13.6

13.8

Poly

phenols

(%

) -

Septe

mber

Dead Survived

Dead Survived

Variable Z p-value

Tannins, seasonal trend 2.58 0.009

Polyphenol September 2.35 0.018

Polyphenol, seasonal trend 2.61 0.008

Estimate Standard Wald p

Interc 0.865 0.290 8.914 0.003

Polyphenols (%) - Seasonal trend -0.262 0.124 4.437 0.035

Variable Dead Survived

Tannins (%) - seasonal trend 1.1 (0.1) 0.8 (0.1)

Polyphenols (%) - september 12.5 (0.1) 12.0 (0.1)

Polyphenols (%) - seasonal trend 2.2 (0.1) 1.8 (0.1)

Second - third instar: temperature

Mean

±SE

±1.96*SE

Outl iers

0 18.8

9.0

9.2

9.4

9.6

9.8

10.0

10.2

10.4

10.6

10.8

Tem

epra

ture

(°C

)

Dead Survived

II - III instar Mean (SE)

Dead 9.6 (0.1)

Survived 10.1 (0.1)

Estimate Standard Wald p

Interc 3.997 1.561 6.552 0.010

Temperature 0.393 0.157 6.218 0.013

N dead = 77 N survived = 67

Colias palaeno - Comparison with german sites

Jachenau Italy Wilcoxon TestMean SE Mean SE Z p-value

Tannins (First) 11.61 0.24 8.01 0.16 7.455 0.000

Polyphenols (First) 15.55 0.29 10.29 0.20 7.589 0.000

Tannins (Second) 12.04 0.25 9.06 0.22 6.560 0.000

Polyphenols (Second) 15.75 0.29 12.51 0.28 6.242 0.000

Diff Tannins 0.43 0.14 1.05 0.15 -2.961 0.003

Diff Polyphenols 0.20 0.17 2.22 0.20 -6.107 0.000

M-W Test Italy Germany

Secondary metabolites:

higher in Germany

Seasonal trend: higher

in Italy

Mean

±SE

±1.96*SE

Outl iersgermania ital ia

Trend fenologico

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

Tannin

i

Mean

±SE

±1.96*SE

Outl iersgermania ital ia

Contenuto fogliare

6

7

8

9

10

11

12

13

14

Tannin

i

Germany Italy Germany Italy

Tan

nin

s (%

)

Tan

nin

s (%

)

First sampling Seasonal trend

1. Higher density and survival rate near the timberline

3. Possibility of phenological asynchrony

2. Different parameters (vegetation structure, secondary metabolites, temperature) are important for different immature

stages

Colias palaeno - Conclusion

Aknowledgements

Simona Bonelli

Giorgio Buffa

Matthias Dolek

Emilio Balletto

Jörg Heilmann

Guido Jürgenlimk

Peter Poschlod

In the laboratory

Hannah Bergmann

Sebastian Schwindl

And for the field work

Serena Magagnoli

Martina Zarri

Claudio Albertone

Federico Folini

Thanks for your attention!