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PeerJ. 2019 Feb 28;7:e6530. doi: 10.7717/peerj.6530. eCollection 2019.

Winter temperature predicts prolonged diapause in pine processionary moth species across their geographic range.

Author information

1
DAFNAE, University of Padova, Legnaro Padova, Italia.
2
PAU, Università Mediterranea, Reggio Calabria, Italia.
3
Faculté des Sciences, Université Cadi Ayyad, Marrakech, Morocco.
4
Department of Ecology, Universidad de Granada, Granada, Spain.
5
Unité de Recherche de Zoologie Forestière, INRA, Orleans, France.
6
School of Biological Sciences, The University of Queensland, Brisbane, Australia.
7
Arboretum Bajnem, Institut National Recherche Forestiere, Alger, Algeria.

Abstract

Prolonged diapause occurs in a number of insects and is interpreted as a way to evade adverse conditions. The winter pine processionary moths (Thaumetopoea pityocampa and Th. wilkinsoni) are important pests of pines and cedars in the Mediterranean region. They are typically univoltine, with larvae feeding across the winter, pupating in spring in the soil and emerging as adults in summer. Pupae may, however, enter a prolonged diapause with adults emerging one or more years later. We tested the effect of variation in winter temperature on the incidence of prolonged diapause, using a total of 64 individual datasets related to insect cohorts over the period 1964-2015 for 36 sites in seven countries, covering most of the geographic range of both species. We found high variation in prolonged diapause incidence over their ranges. At both lower and upper ends of the thermal range in winter, prolonged diapause tended to be higher than at intermediate temperatures. Prolonged diapause may represent a risk-spreading strategy to mitigate climate uncertainty, although it may increase individual mortality because of a longer exposure to mortality factors such as predation, parasitism, diseases or energy depletion. Climate change, and in particular the increase of winter temperature, may reduce the incidence of prolonged diapause in colder regions whereas it may increase it in warmer ones, with consequences for population dynamics.

KEYWORDS:

Mortality; Pest; Pinus; Pupa; Soil; Temperature

Conflict of interest statement

The authors declare there are no competing interests.

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