Larval fitness of a generalist butterfly under experimental warming and spring drought depends on host species and timing

Climate change is expected to lead to faster development times in herbivorous insects, but precise predictions are challenging because excessive dry weather may offset benefits and host plants may respond in different ways. Conflicting evidence from many laboratory studies suggest that water stress may enhance or lower plant nutritional quality and palatability, but few studies expose both trophic levels to stressful conditions. We investigated the egg-laying preferences and larval performance of the green hairstreak butterfly (Callophrys rubi) at two elevations of a boreal forest in Western Norway during an unusually warm spring, and under artificially warmed conditions. At both sites, adults initially preferred to oviposit on the early flowering bilberry (Vaccinium myrtillus) and switched to lingonberry (V. vitis-idaea) when it began to flower later in the season. However, larvae performed poorly on the early season host bilberry, particularly under the most stressful conditions at th..., , # Host choice and larval fitness of a generalist butterfly under drought stress depends on host species and timing

Dataset DOI: [10.5061/dryad.dncjsxm9k](10.5061/dryad.dncjsxm9k)

## Description of the data and file structure

The data in the file Hairstreak_data.csv were collected during an experiment on the green hairstreak butterfly at two sites at a boreal forest in Western Norway. Small field cages were erected in the field offering adult butterflies a choice of bilberry or lingonberry. Eggs laid were removed and returned to the lab until hatching. When larvae were 5-7 days old they were transported back to the field and randomly assigned to a block, treatment (Warming or Ambient) and host species (bilberry or lingonberry). Healthy host plant ramets between 12 and 25 cm in height were then selected as close to the edge of the plots as possible in order to prevent perturbation of plots being used for other studies. Larvae were placed on their selected host and prevented from escapi..., ,