Food-plant-associated predation risk and its impact on larval development and adult morphology in a specialist butterfly

Predation influences herbivore behavior, physiology, and reproductive success through both direct consumption and non-lethal effects arising from predation risk alone. Plant traits, including defensive traits and architecture, can also influence herbivores both directly and indirectly, either by affecting feeding efficiency or by affecting herbivores' risk of predation. Yet, it remains unclear how predators and plant traits interact to shape the developmental outcomes of larval herbivores, particularly under field conditions. To understand larval performance within a tritrophic framework, we investigated how predation risk and food-plant identity influence caterpillar development and subsequent adult morphology using the monarch butterfly (Danaus plexippus) as a focal species. We compared responses to predation risk in monarch caterpillars feeding on two common species of western milkweed, Asclepias speciosa and Asclepias fascicularis, which differ in various traits, including defe..., We conducted a 2x2 factorial common garden experiment over two consecutive years (2018, N = 322; 2019, N = 171) in Reno, NV, to assess the effects of predation risk and host-plant identity (Asclepias speciosa and A. fascicularis) on monarch butterfly (Danaus plexippus) larval development and adult morphology. Predation risk was manipulated using predator-exclusion cages and open-sided \"mock-cages\" (referred to as \"roof\" in the dataset). Gardens were planted each year with first-year milkweed plants grown from seeds collected from multiple wild populations to account for intraspecific variation in plant chemistry and phenotype. Monarch larvae (F2 generation from local wild-caught females) were placed individually on plants and tracked daily from the second instar until adulthood or death. We recorded larval survival, developmental stage progression, and the timing of reaching the fifth instar. Adults were measured for dry weight and wing morphology (length, width, area, an..., , # Food-plant-associated predation risk and its impact on larval development and adult morphology in the monarch butterfly (*Danaus plexippus*)

Dataset DOI: [10.5061/dryad.51c59zwgx](https://doi.org/10.5061/dryad.51c59zwgx)

## Description of the data and file structure

These data were collected from two years (2018–2019) of common-garden experiments assessing the effects of larval host-plant species and predator exposure on monarch butterfly (*Danaus plexippus*) development and adult morphology. Monarch larvae were tracked daily from second instar until adulthood or death on either predator-exclusion or control plants, with one larva per plant. Larval survival, developmental timing, and pre-pupal weight gain were recorded. Adults that emerged were checked for OE infection, weighed, and measured for wing morphometrics, including length, width, area, loading, and roundness. Plant architecture was also recorded prior to larval introduction.

### Files and variables

#### File: 2019_VR_Pr..., ,