Interspecific differences in thermal tolerance landscape explain aphid community abundance under climate change

A single critical thermal limit is often used to explain and infer the
impact of climate change on geographic range and population
abundance. However, it has limited application in describing the temporal
dynamic and cumulative impacts of extreme temperatures. Here, we
used a thermal tolerance landscape approach to address the
impacts of extreme thermal events on the survival of co-existing
aphid species (Metopolophium dirhodum, Sitobion avenae and
Rhopalosiphum padi). Specifically, we built the thermal death time (TDT)
models based on detailed survival datasets of three aphid species
with three ages across a broad range of stressful high (34–40 ÅãC) and
low (−3∼-11 ÅãC) temperatures to compare the interspecific and
developmental stage variations in thermal tolerance. Using these
TDT parameters, we performed a thermal risk assessment by calculating the
potential daily thermal injury accumulation associated with the
regional temperature variations in three wheat-growing sites along a
latitude gradient. Results showed that M. dirhodum was the most
vulnerable to heat but more tolerant to low temperatures than R.
padi and S. avenae. R. padi survived better at high temperatures than
Sitobion avenae and M. dirhodum but was sensitive to cold. R.
padi was estimated to accumulate higher cold injury than the other
two species during winter, while M. dirhodum accrued more heat
injury during summer. The warmer site had higher risks of heat
injury and the cooler site had higher risks of cold injury along a
latitude gradient. These results support recent field
observations that the proportion of R. padi increases with the increased
frequency of heat waves. We also found that young nymphs
generally had a lower thermal tolerance than old nymphs or adults. Our
results provide a useful dataset and method for modelling and
predicting the consequence of climate change on the
population dynamics and community structure of small insects.