Chemical communication is common across all organisms. Insects in particular use predominantly chemical stimuli in assessing their environment and recognizing their social counterparts. One of the chemical stimuli used for recognition in social insects, such as ants, are long-chain hydrocarbons. Next to providing waterproofing, these surface hydrocarbons serve as a signature mixture, which ants can perceive, and use to distinguish between strangers and colony mates, and to determine caste, sex, or reproductive status of another individual. They can be both environmentally and endogenously acquired. The surface chemistry of adult workers has been studied extensively in ants, yet the pupal stage has rarely been considered. Here we characterized the surface chemistry of Formica exsecta pupae, and examine differences among sexes, castes (reproductive vs. worker), and types of sample (developing individual vs. cocoon envelope). We found quantitative and qualitative differences among both castes and types of sample, but male and female reproductives did not differ in their surface chemistry. We also found that the pupal surface chemistry was more complex than that of adult workers in this species. These results improve our understanding of the information on which ants base recognition, and highlights the diversity of surface chemistry in social insects across developmental stages.

Date of data collection: 1.6-31.7 2012

Geographic location of data collection: SW Finland, Tvärminne zoological station

1. Methods used for collection/generation of data:

• Field collection of ant pupae from 35 colonies, 3-5 individuals per colony
• Standard GCMS-analysis on adult workers, pupal cases and corresponding developing individuals inside the pupae. All castes, workers, new queens, and males included

2. Methods for processing the data:

• Surface chemicals were extracted by washing each individual (cocoon, and developing individual separately) in HPLC grade pentane, and analysed with an Agilent 7890A GC coupled with an Agilent 5975c MS (described in Pulliainen et al. see above)
• Both raw, proportional, and transformed (Aitchison) data are included

3. Instrument- or software-specific information needed to interpret the data:

• Excel or other spreadsheet

6. Quality-assurance procedures performed on the data:

Chemical analyses were performed by an experienced technician with a Master in Chemistry; the GC-MS was tuned every day and a cleaning procedure applied every morning. The samples did not contain any contaminations.

7. People involved with sample collection, processing, analysis and/or submission:

Unni Pulliainen, Nick Bos, Patrizia d’Ettorre, Liselotte Sundström

DATA & FILE OVERVIEW

1. File List:

• F exsecta CHC raw data and transformations (excel)
• F exsecta CHC raw data and transformations (txt)

2. Are there multiple versions of the dataset? no

DATA-SPECIFIC INFORMATION FOR: F exsecta chc raw data and transformations (3 sheets)

RAW reads

• 36 variables
• the first 4 variables describe categories (Colony code, Caste, sample type, and replicate)
• the following describe the compounds in the order of retention times (# carbon atoms)

PERCENTAGE of RAW READ

• 36 variables, the same is in RAW reads, but with original zero values (see below)
• shows the percentage each compound comprises the total profile of each individual

AITCHISON transformation

• RAW reads transformed such that for each compound X = [log (x₁/g_(x))...log x_D/g_(x)], where g = the geometric mean of the raw reads for each compound
• to allow this transformation, zero values in the raw read sheet has been replaced with the value 1

Each sheet comprises two rows the first of which states the type of data (raw reads, percentage of raw reads, or Aitchison transformation), and the second the category headers (first four columns), followed by the chemical formula of the compound.

Categories are: Colony ID, Caste (worker, sexual female, male), sample (adult, cocoon, i.e. the envelope of a developing pupa, and developing individual, i.e. the individual inside the cocoon), replicate (3-5 individuals of each caste were analysed; Note: both males and females were not available in all colonies)

Rows 3-597 contain the chemical information for each individual, in total 595 data rows.

MISSING DATA

• None