TY - JOUR
T1 - Establishment and expansion of a Thaumetopoea pityocampa (Den. & Schiff.) (Lep. Notodontidae), population with a shifted life cycle in a production pine forest, Central-Coastal Portugal
AU - Pimentel, Carla Sofia
AU - Calvão, Teresa
AU - Santos, Márcia H.
AU - Ferreira, Cláudia Pio
AU - Neves, M
AU - Nilsson, Jan Åke
PY - 2006/1/1
Y1 - 2006/1/1
N2 - In 1997, a temporally shifted population of Thaumetopoea pityocampa (Den. & Schiff.), was recorded for the first time in a restricted area of the oldest National Pine Forest of Portugal-the National Pine Forest of Leiria. This new population larval development takes place during the summer (summer population-SP), while in the normal population it takes place during the winter (winter population-WP). Between 2000 and 2003, we assessed the distribution and expansion of the SP, and quantified the differences in population densities, mortality and major life history traits with the WP within the Leiria Forest. The SP occurred at higher population levels (5-35% attacked trees) in a large continuous area of young plantations with high tree density, the same area where it was initially discovered. These densities were higher than the ones recorded for the WP in any part of the forest (0-12%), although both populations coexist geographically. The temporally shifted population preferably attacked young plantations. It also expanded south, following the direction of the dominant winds during adult flight. SP had a lower fecundity than the WP, however it benefited from lower egg mortality due mostly to a low rate of parasitism. It also benefited from a lower mortality in the early larval instars leading to low levels of colony extinction. SP larvae take half the time compared to the WP larvae, to reach the same final mass, probably due to the fact that they develop under higher temperature and global radiation. Separated emergence timings of adults lead to an allochronic isolation of the two populations. However, if this might represent an allochronic speciation event has to await further ecological and evolutionary studies of the system.
AB - In 1997, a temporally shifted population of Thaumetopoea pityocampa (Den. & Schiff.), was recorded for the first time in a restricted area of the oldest National Pine Forest of Portugal-the National Pine Forest of Leiria. This new population larval development takes place during the summer (summer population-SP), while in the normal population it takes place during the winter (winter population-WP). Between 2000 and 2003, we assessed the distribution and expansion of the SP, and quantified the differences in population densities, mortality and major life history traits with the WP within the Leiria Forest. The SP occurred at higher population levels (5-35% attacked trees) in a large continuous area of young plantations with high tree density, the same area where it was initially discovered. These densities were higher than the ones recorded for the WP in any part of the forest (0-12%), although both populations coexist geographically. The temporally shifted population preferably attacked young plantations. It also expanded south, following the direction of the dominant winds during adult flight. SP had a lower fecundity than the WP, however it benefited from lower egg mortality due mostly to a low rate of parasitism. It also benefited from a lower mortality in the early larval instars leading to low levels of colony extinction. SP larvae take half the time compared to the WP larvae, to reach the same final mass, probably due to the fact that they develop under higher temperature and global radiation. Separated emergence timings of adults lead to an allochronic isolation of the two populations. However, if this might represent an allochronic speciation event has to await further ecological and evolutionary studies of the system.
KW - Mortality rates
KW - Thaumetopoeinae
KW - Allochronic isolation
KW - Developmental rate
KW - Life cycle shift
UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-33747401968&origin=inward&txGid=2f8c1f8274b2bd85a53b09e592fc06c2
U2 - 10.1016/j.foreco.2006.06.005
DO - 10.1016/j.foreco.2006.06.005
M3 - Article
SN - 0378-1127
VL - 233
SP - 108
EP - 115
JO - Forest Ecology And Management
JF - Forest Ecology And Management
IS - 1
ER -