The influence of diurnal temperature variation on degree-day accumulation and insect life history.

Shi Chen,Shelby J Fleischer,Michael C Saunders,Matthew B Thomas,J Joe Hull

doi:10.1371/journal.pone.0120772

Abstract

Ectotherms, such as insects, experience non-constant temperatures in nature. Daily mean temperatures can be derived from the daily maximum and minimum temperatures. However, the converse is not true and environments with the same mean temperature can exhibit very different diurnal temperate ranges. Here we apply a degree-day model for development of the grape berry moth (Paralobesia viteana, a significant vineyard pest in the northeastern USA) to investigate how different diurnal temperature range conditions can influence degree-day accumulation and, hence, insect life history. We first consider changes in diurnal temperature range independent of changes in mean temperatures. We then investigate grape berry moth life history under potential climate change conditions, increasing mean temperature via variable patterns of change to diurnal temperature range. We predict that diurnal temperature range change can substantially alter insect life history. Altering diurnal temperature range independent of the mean temperature can affect development rate and voltinism, with the magnitude of the effects dependent on whether changes occur to the daily minimum temperature (Tmin), daily maximum temperature (Tmax), or both. Allowing for an increase in mean temperature produces more marked effects on life history but, again, the patterns and magnitude depend on the nature of the change to diurnal temperature range together with the starting conditions in the local environment. The study highlights the importance of characterizing the influence of diurnal temperature range in addition to mean temperature alone.

Highlights

Climate warming is expected to influence the dynamics and distribution of terrestrial ectotherms, such as insects, because their physiology and ecology are strongly dependent on ambient temperature [1,2,3,4,5,6,7,8]
These studies have highlighted the importance of considering diurnal temperature range (DTR thereafter) along with mean daily temperature in order to fully understand the consequences of climate change
It had been estimated that the annual mean surface temperature will increase by 2–6°C by the end of the 21st century [20,22]. We comprehensively assigned both k1 and k2 to change from −0.4 to 0.4 to bracket this maximum potential increase

Summary

Introduction

Climate warming is expected to influence the dynamics and distribution of terrestrial ectotherms, such as insects, because their physiology and ecology are strongly dependent on ambient temperature [1,2,3,4,5,6,7,8]. Diurnal Temperature Variation Insect Life History temperature at relatively coarse temporal scales (e.g. seasonal or yearly mean temperature) [6], recent studies have demonstrated that temperature variation at much finer scales can influence insect life history [9,10,11,12,13,14] These studies have highlighted the importance of considering diurnal temperature range (DTR thereafter) along with mean daily temperature in order to fully understand the consequences of climate change. There is evidence to support greater increases in Tmin relative to Tmax, resulting in smaller DTRs [19,20,21,22] Given these contrasting scenarios, there is a need to comprehensively and systematically investigate how changes in DTR could impact insect life history

Methods

Results

Conclusion