Orthosia simulation experiment data

Consequences of climate change-driven shifts in the relative timing of
spring activities of interacting species are insufficiently understood,
especially for insects. We use a controlled experiment which simulates a
trophic mismatch scenario in which lepidopteran larvae predominately feed
on older leaves due to foliage developing faster than larvae growth rates.
As a case study our experiment uses Orthosia cerasi, which is a widespread
but declining woodland moth whose UK declines appear to be driven by
warming temperatures. In the control experiment larvae are fed young oak
Quercus robur leaves (bud burst stages six and seven), whilst in the
treatment newly emerged larvae are fed young leaves but then gradually
transition to feed on older leaves (post bud burst stage seven). We assess
impacts on duration of the larval stage, pupal size and overwintering
duration and survival. Larvae in the phenological mismatch treatment had a
longer larval period, and smaller and lighter pupae. Larval diet did not
carry over to influence emergence dates as earlier pupation of control
larvae was balanced by an equivalent increase in the duration of the pupal
stage. Increased time spent as larvae could increase predation rates from
avian predators, whilst slowing the seasonal decline in food availability
for those bird species. Reduced pupal size and weight are indicators of
lower fecundity in emerging adults. Notably, we find that adults emerging
from the mismatch treatment exhibited greater rates of abnormal vestigial
wing development, which is likely to further reduce fitness. Trophic
mismatches in which caterpillars have reduced availability of young leaves
may thus contribute to the population declines observed in many woodland
moth species due to increased mortality at larval stages, and adverse
effects of early life conditions that reduce the reproductive success of
emerging adults.