Joint IUFRO 7.03.01, 7.03.06 and 7.03.14 Working Party Meeting. Antalya, Turkey, 9-14 April 2014

Climate niche of the summer pine processionary moth: potential distribution in Portugal and across the Mediterranean basin J.-P.

1 Rossi ,

H.

2 Santos ,

S.

3 Rocha ,

M.-R.

4 Paiva ,

C.

1 Kerdelhué

and M.

3 Branco

1INRA,

UMR CBGP, Montpellier, France [[email protected]] 2DCEA, Faculty of Sciences and Technology, Universidade Nova de Lisboa, Portugal 3CEF, Instituto Superior de Agronomia, Universidade de Lisboa, Portugal 4CENSE, Faculty of Sciences and Technology, Unversidade Nova de Lisboa, Portugal

Introduction The pine processionary moth, Thaumetopoea pityocampa, is a Mediterranean insect that typically reproduces in the summer while larvae develop in the winter. A phenologically atypical population, hereafter named "summer population" (SPPM), was detected in 1997 in the region of Leiria, Portugal. For this peculiar population, reproduction occurs in May and larval development in the summer. The objectives of the present study were: i) to predict the potential range of the SPPM across the Mediterranean basin using species distribution modelling and ii) to assess the patterns of dispersion since 1997 and simulate potential expansion in Portugal.

Species Distribution Modelling We modelled the SPPM potential distribution using the MaxEnt (maximum entropy) algorithm and the following climate descriptors: •  Annual Mean Temperature •  Max Temperature of Warmest Month •  Min Temperature of Coldest Month •  Mean Temperature of Warmest Quarter •  Mean Temperature of Coldest Quarter The model was fitted on the basis of the present SPPM distribution in Portugal. Projecting the model across the Mediterranean region yielded an estimate of climate suitability hence the SPPM potential geographical distribution.

SPPM potential distribution

The potential distribution of the SPPM is very limited due to its apparent peculiar climate requirements : mild winters and cool summers

Simulating SPPM expansion in Portugal We further implemented dispersal and landscape information into the former SPPM distribution model and simulated the population expansion since its first observation back in 1997. We used the MigClim model (Engler et al. Ecography 35, 872-878) with : þ broadleaved stands act as barriers to dispersal þ mixed and pure coniferous stands were equally suitable habitats þ open habitats were not taken as barriers because trees outside forests allow dispersal þ SPPM dispersal parameters equal to those of the typical PPM. 1997

Observed distribution in 2013

In Portugal the SPPM is expected to expand southwards and reach Lisbon Since 1997, the SPPM has expanded in the Leiria region where coniferous forest are abundant

today

In the future, broadleaved forests and the scarcity of pine plantations may slow down its expansion southwards Scattered host ornamental trees may compensate the absence of pine stands

2035

Conclusions •  The SPPM appears to be distributed in areas characterized by peculiar climatic conditions. Under the assumption of no ecological shift, it can be expected to remain localized within its present area of distribution and thus the risk of a largescale biological invasion is not high •  The expansion of the SPPM will, most probably, reach the Lisbon area within the next decades, invading highly inhabited and touristic areas, where the occurrence of urticating larvae in the summer would lead to serious public health problems