DOI: 10.5061/dryad.sn02v6xjv
title: Larval development and diapause induction under climate change: an experimental test with the Wall Brown butterfly

description: Under climate change, organisms with complex life cycles like insects are
 confronted with environmental cues that may interfere with their life
 cycle regulation, including diapause induction. Maladaptive responses to
 novel conditions may contribute to local or regional population declines
 and extinctions. In NW-Europe, the Wall Brown butterfly (Lasiommata
 megera) is a multivoltine species whose regional decline has been
 hypothesised to be related to recent warming in late summer and autumn
 increasing the probability of producing a late third generation instead of
 going into larval diapause to hibernate. To test this lost generation
 hypothesis, we exposed young larvae of different population origins to
 outdoor conditions and in situ warming (i.e., increased temperature at the
 level of the host plant by 0.5 to 3°C depending on the month). The warming
 treatment resulted in shorter larval developmental times and reduced adult
 body size. However, the population origin and the temperature treatment
 did not affect the probability to produce a third generation of adult
 butterflies at the end of summer. Yet, families showed substantial
 variation for the probability to induce a third generation. Overall, we
 observed reduced larval survival in the warming treatment. We discuss the
 implications of these results for the conservation of the Wall Brown in
 NW-Europe and, in a broader manner, for life cycle regulation in insects
 under rapid climate change.
description: # Kaiser & Van Dyck, 2025. Larval development and diapause induction
 under climate change: an experimental test with the wall brown butterfly
 --- This dataset accompanies the study “Larval development and diapause
 induction under climate change: an experimental test with the wall brown
 butterfly”. The dataset is provided as a single Excel file containing two
 worksheets: “Development and survival” and “Body size and dev. time”. All
 data are raw (unprocessed) and correspond to individual-level measurements
 collected during the experiment. The “Development and survival” sheet
 contains data on larval development pathways (direct development vs.
 diapause) and larval survival outcomes. The “Body size and dev. time”
 sheet contains data on developmental time and adult body size (estimated
 from wing area). Developmental time and wing area are reported only for
 individuals that emerged by the end of the first autumn (i.e., adults that
 followed a direct development pathway). ## Descriptions ###
 "Development and survival" sheet * *Individual*: Unique
 identifier assigned to each larva in the study * *Family*: Identifier for
 the family to which each larva belongs * *Site_Of_Origin*: Identifier for
 the capture site associated with each family * *Origin*: Region of origin
 of the family * Coast = Belgian coast * Lowlands = Inland lowlands *
 Uplands = Inland uplands * *Treatment*: Thermal treatment applied to
 larvae (Control or Warming) * *Date_Of_Placement*: Date when the larva was
 transferred to the outdoor cage * *Direct_Development*: Indicates whether
 the larva developed directly, i.e., emerged as an adult in autumn (1 =
 Yes; 0 = No) * *Winter_Survival*: Indicates whether the larva emerged as
 an adult in spring (1 = Yes; 0 = No; empty cell = larva already emerged in
 autumn) * *Overall_Survival*: Indicates whether the larva successfully
 developed into an adult at any time during the experiment (1 = Yes; 0 =
 No) ### "Body size and dev. time" sheet * *Individual*: Unique
 identifier assigned to each larva in the study * *Family*: Identifier for
 the family to which each larva belongs * *Site_Of_Origin*: Identifier for
 the collection site associated with each family * *Treatment*: Thermal
 treatment applied to larvae (Control or Warming) * *Origin*: Region of
 origin of the family * Coast = Belgian coast * Lowlands = Inland lowlands
 * Uplands = Inland uplands * *Date_Of_Placement*: Date when the larva was
 transferred to the outdoor cage * *Date_Of_Emergence*: Date when the
 individual emerged as an adult butterfly (empty cell = unknown) *
 *Estimated_Developmental_Time*: Number of days between *Date_Of_Placement*
 and *Date_Of_Emergence*, used as a proxy for developmental time (empty
 cell = unknown) * *Sexe*: Sex of the individual (Female or Male) *
 *Wing_Area*: Area of the least damaged forewing, measured in mm²