Invading pine processionary moth benefits from escape from natural - - PowerPoint PPT Presentation
Invading pine processionary moth benefits from escape from natural enemies. Charles-Edouard IMBERT Alain ROQUES Forest Zoology INRA Orlans, France Climate change EEA Report No 4/2008 Global warming : Approximately + 0.6 C during the
Charles-Edouard IMBERT Alain ROQUES
Forest Zoology – INRA Orléans, France
EEA Report No 4/2008
Effects on physiology Effects on phenology
Global warming : Approximately + 0.6° C during the l ast century and between +1.4 and +5.8 ° C during this century.
The Pine Processionary Moth, Thaumetopoea pityocampa (Denis & Schiffermüller, 1775) (Lepidoptera, Notodontidae). Moth’s larvae grow during the winter and depend directly on temperature :
C (depends on colony size)
(night air temperature above 0° C and temperature inside the nest above 9° C on the preceding day)
Range distribution in constant progression northward (27 km per decade between 1972 et 2004) and in altitude.
Artificially introduced populations above the front around Paris and in the east of France.
Robinet & al, 2007.
4 species of egg parasitoids reported in France
Ooencyrtus pityocampae (Encyrtidae) Anastatus bifasciatus (Eupelmidae) Baryscapus servadeii (Eulophidae) Trichogramma sp (Trichogrammatidae)
Differences in parasitism rate, specific richness, abundance, phenology along the expansion gradient ? Do all species will respond in the same way ? Same effect in latitudinal gradient than in altitudinal gradient ? With the range expansion of the PPM we don’t know how the natural enemies and in particular the egg parasitoids will respond.
Paris Basin transect Massif Central transect French Alps transect
Paris Basin
6 sampling locations 157 egg-batches sampled
Paris Basin transect Massif Central transect French Alps transect
French Alps
4 sampling locations 45 egg-batches sampled
Paris Basin transect Massif Central transect French Alps transect
Massif Central
8 sampling locations 102 egg-batches sampled
For each egg-batch, scales were removed after the hatch of parasitoids. Every egg without the characteristic hole of caterpillar hatching was open and parasitoid species was determined with the meconium after Tanzen and Schmidt (1995).
Meconium of Ooencyrtus pityocampae at early stage (1) and late stage (2) of parasitism Meconium of Baryscapus servadeii
Hatching hole of caterpillar Hatching hole of parasitoid
38356 eggs were analysed. Significant differences between front populations and core populations. Parasitism rate is higher in core population than in front populations. No parasitoids found in artificially introduced populations.
R²=0.04234
a a a b b b Mann-Whitney test (p-value < 0.05)
3 parasites species were found
area to front area. Generalists parasitoids seem to have more difficulties to follow the pine processionary moth
9143 eggs were analysed. Significantly higher parasitism in core populations than in front populations
R²: 0.1513
a b ab b Mann-Whitney test (p-value < 0.05)
4 parasitoid species found
Two main parasitoids species : B. servadeii and O. pityocampae found in each sample locations. The rate of specialist parasitoid increase near the front populations.
24218 eggs analysed Significant differences between front populations and core populations. Parasitism rate is higher in core population than in front populations.
R²: 0.0381
a ab bc bc bc c Mann-Whitney test (p-value < 0.05)
3 parasitoid species found
Two main parasitoids species : B. servadeii and O. pityocampae found in each sample locations as in French Alps transect. The rate of specialist parasitoid decrease near the front populations
In the 3 transects, latitudinal as altitudinal, we observed a reduction of parasitism near the range boundaries of pine processionary moth. Parasitism rate and species richness are different between the transects, we can’t explain that now. But it is only one year sampling so we can’t observe interanual variations. An
With less mortality because of egg-parasitism in the front area, the pine processionnary moth might have greater colonies that could provide a better survival during the winter and they could colonize more easily colder places.