DOI: 10.5061/dryad.rr4xgxdcn
title: Data from: Not just the sum of its parts: Geographic variation and nonadditive effects of pyrazines in the chemical defence of an aposematic moth

description: Chemical defences often vary within and between populations both in
 quantity and quality, which is puzzling if prey survival is dependent on
 the strength of the defence. We investigated the within- and
 between-population variability in chemical defence of the wood tiger moth
 (Arctia plantaginis). The major components of its defences, SBMP
 (2-sec-butyl-3-methoxypyrazine) and IBMP (2-isobutyl-3-methoxypyrazine),
 are volatiles that deter bird attacks. We hypothesised that 1) variation
 in the chemical defences of male wood tiger moths reflects the local
 predation pressure; 2) observed differences in quantity and quality of
 defence among populations have a genetic basis; and 3) increasing
 concentrations of SBMP and IBMP will elicit greater aversive reactions in
 predators, with the two pyrazines having an additive effect on predators’
 avoidance. We found that 1) the chemical defence of wild moths partly
 reflects local predator selection: high predation pressure populations
 (Scotland and Georgia) had stronger chemical defences, but not lower
 variance, than the low-predation populations (Estonia and Finland). 2)
 Based on the common garden results, both genetic and environmental
 components seem to influence the strength of chemical defence in moth
 populations; and 3) IBMP alone did not provide protection against bird
 predators but worked against bird attacks only when combined with SBMP,
 and while SBMP was more effective at higher concentrations, IBMP was not.
 Altogether this suggests that, when it comes to pyrazine concentration,
 more is not always better, highlighting the importance of testing the
 efficacy of chemical defence and its components with relevant predators,
 as extrapolating from chemical data may be less than straightforward.
description: Methods are described in the related paper.
description: # Not just the sum of its parts: Geographic variation and
 non-additive effects of pyrazines in the chemical defence of an aposematic
 moth BirdGeoFinControl.txt and Pyrazines_Populations.txt are the raw data
 in a format that can be opened in Wordpad or Excel. The
 BirdGeoFinControl.txt file includes raw data for the predators'
 response to the thoracic fluid of Georgian and Finnish Wood Tiger Moth
 populations, while the Pyrazines_Populations.txt is the measure of
 pyrazines of different Wood Tiger Moth populations The headers of columns
 for the **BirdGeoFinControl.txt** are defined below: ID: ID of individual
 moth Volume: volume of the Wood Tiger Moth thoracic fluid (microL)
 population: population of each individual location: location (country)
 from where each individual is from origin: laboratory origin or wild
 origin of each individual BirdID: ID individual of each bird Date: date of
 the experiment Trial: trial (1,2,3,4). trial 1 and 4 were water and 2 and
 3 were with the thoracic fluid Hesitation: hesitation time measured as
 time in seconds from seeing the oat to pecking/eating the first oat
 Length: duration time of each trial (min) Proportion_eaten: Proportion of
 oat eaten in each trial Beak_cleaning: a disgust behaviour measured as the
 number of bouts where the bird wiped its beak against a surface such as
 the perch Drinking: the number of times the bird drank water, which is a
 behaviour that can increase in response to distasteful food The headers of
 columns for **Pyrazines_Populations.txt** are defined below: sample: ID of
 individuals population: population of each individual location: location
 (country) from where each individual is from origin: laboratory origin or
 wild origin of each individual year: year of the sampling SBMP: SBMP
 measurament from the GC-MS IBMP: IBMP measurament from the GC-MS 1ng_SBMP:
 standard amount of SBMP 1ng_IBMP: standard amount of IBMP SBMP_ng: SBMP
 amount in NG IBMP_ng: IBMP amount in ng ratio: ratio of IBMP to SBMP The
 headers of columns for **weight_LABmoths.txt** are defined below: sample:
 ID of individuals population: population of each individual location:
 location (country) from where each individual is from origin: laboratory
 origin or wild origin of each individual year: year of the sampling SBMP:
 SBMP measurament from the GC-MS IBMP: IBMP measurament from the GC-MS
 1ng_SBMP: standard amount of SBMP 1ng_IBMP: standard amount of IBMP
 SBMP_ng: SBMP amount in NG IBMP_ng: IBMP amount in ng ratio: ratio of IBMP
 to SBMP weight: weight in milligrams of the wood tiger moths lab
 populations