Data on female oviposition behaviour of the Pararge aegeria butterfly in outdoor cages (2019–2020)
Data files
Mar 22, 2023 version files 430.85 KB
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femdata.csv
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ovimdata.csv
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README.md
Abstract
We studied oviposition behavior in a butterfly (Pararge aegeria) that used to be confined to forest, but recently colonized anthropogenic areas too. This provides an ideal study system when trying to understand the underlying processes of niche expansion and colonisation success. The dataset produced allows us to test to what extent ecotype origin (agricultural vs. forest landscape types) and larval developmental conditions (open field vs. canopy-covered forest floors) affect multiple features of oviposition behahaviour. We also performed multiple behavioural trials per individual and considered changes in oviposition site preference within and over trials.
The two provided files contain all behavioral or independent variables that were obtained during behavioural tracking of the oviposition behaviour of the Speckled Wood butterfly (Pararge aegeria) in an outdoor cage in 2019 and 2020.
In the 'femdata' file, each line contains all dependent (e.g., proportion of time spent active) and independent variables (e.g. ecotype) that apply for a single observation trial of 30 minutes of a single individual.In total, 211 observation trials were performed, by 110 different female individuals.
In the 'ovimdata' file, each line contains all variables for a single oviposition bout (i.e., if a butterfly curls its abdomen on a surface and lays eggs). Examples include number of eggs per bout, the height above ground where an egg was laid and temperature at the egg laying site. These data were for example used to track changes over consecutive bouts within a single trial. In total 275 oviposition bouts were observe, laid by 85 different female individuals.
Data of the ovimdata file were also implemented in the femdata file. For example, in the femdata file information can be obtained about the properties of the first oviposition bout an individual made during that trial (starting with 'b1').
Methods
We caught females of either forest or agricultural ecotype and allowed their larval offspring to experience early-habitat cues in either open field or woodland conditions. Two times a week, grass pots were watered and checked for pupae. Pupae were collected, placed individually in plastic cups, and kept under standardized lab conditions (day/night: 23/16 °C; light/dark: 15/9 h) until adult emergence. Two to three days after adult emergence, one F1-female and three F1-males were introduced together into a small cage (0.3 x 0.3 x 0.3 m) for 24 h to ensure mating. Males and females that were allowed to mate came from different broods, but were of the same maternal ecotype. After mating, females were kept in the dark at lower temperatures (temperature day/night: 16/14 °C) in a Sanyo incubator.
Adult females were tested in large outdoor cages. These cages (12 x 4.2 x 2.5 m) were located at forest edges, where host grass species of P. aegeria naturally occurred. From mid-September to mid-October 2019, and from the end of July to mid-September 2020, the behavior of 110 F1-offspring females was observed. Each female was individually and gently released from a plastic cup that was placed on a small platform in the central part of the outdoor cage. Next, the female’s behavior was tracked during an observation trial of 30 minutes. For each female, two observation trials were done, which were separated by 1 to 4 hours intervals on days that were suitable for adult butterfly activity (i.e., ambient temperature > 15°C and sunny to semi-clouded conditions). Before each observation, the following environmental variables were recorded: ambient temperature and relative humidity (at a central part of the cage, 18 cm above surface in the shade), degree of cloudiness (three-level scores: 0: open sky; 1: < 40% cloud coverage; 2: > 40% cloud coverage), and cage identity. Behavioral data (type of behavior, proportion of time spent for each type of behavior and proportion of time spent in each segment of the outdoor cage) were recorded using the open-source logging software BORIS. Types of behavior included flying (distinguishing three types: bumping against the cage netting, fluttering high or low, and flying in a directional fashion), resting, walking, and ovipositing. Once a butterfly took off after an oviposition event, a small marking stick was planted and the following data were registered after observation: number of eggs, grass species, height above ground, air temperature and relative humidity near the egg, distance of the oviposition location from woodland edge (0-15 m), presence and orientation of nearby vertical structure within a vicinity of 10 cm of the egg, and finally, the grade of shade on oviposition substrate within a vicinity of 2 cm of the egg (0: fully exposed, 1: more sunlit than shaded, 2: more shaded than sunlit, 3: fully shaded). After an observation, eggs were carefully removed. A single person (S.B.) made all observations from inside the cage. After the 30-minute observation trial, the butterfly was recaptured by gently placing the cup over the butterfly as soon as it stopped flying.
Pending their test in the cage and after their test, females were kept in a plastic cup in the dark in a cool box. Every two consecutive trials were done with a female of the forest and agricultural ecotype in random order. Each day, behavioral data were collected from 1 to 4 females. Consecutive trials of the same female remained in the same cage. Every two days, the observer switched cages.