Assessing insect responses to climate change: What are we testing for? Where should we be heading?

Abstract

To understand how researchers are tackling globally important issues, it is crucial to identify whether current research is comprehensive enough to make substantive predictions about general responses. We examined how research on climate change affecting insects is being assessed, what factors are being tested and the localities of studies, from 1703 papers published between 1985 and August 2012. Most published research (64%) is generated from Europe and North America and being dedicated to core data analysis, with 29% of the studies analysed dedicated to Lepidoptera and 22% Diptera: which are well above their contribution to the currently identified insect species richness (estimated at 13% and 17% respectively). Research publications on Coleoptera fall well short of their proportional contribution (19% of publications but 39% of insect species identified), and to a lesser extent so do Hemiptera, and Hymenoptera. Species specific responses to changes in temperature by assessing distribution/range shifts or changes in abundance were the most commonly used methods of assessing the impact of climate change on insects. Research on insects and climate change to date is dominated by manuscripts assessing butterflies in Europe, insects of economic and/or environmental concern in forestry, agriculture, and model organisms. The research on understanding how insects will respond to a rapidly changing climate is still in its infancy, but the current trends of publications give a good basis for how we are attempting to assess insect responses. In particular, there is a crucial need for broader studies of ecological, behavioural, physiological and life history responses to be addressed across a greater range of geographic locations, particularly Asia, Africa and Australasia, and in areas of high human population growth and habitat modification. It is still too early in our understanding of taxa responses to climate change to know if charismatic taxa, such as butterflies, or disease vectors, including Diptera, can be used as keystone taxa to generalise other insect responses to climate change. This is critical as the basic biology of most species is still poorly known, and dominant, well studied taxa may show variable responses to climate change across their distribution due to regional biotic and abiotic influences. Indeed identifying if insect responses to climate change can be generalised using phylogeny, functional traits, or functional groups, or will populations and species exhibit idiosyncratic responses, should be a key priority for future research.

Mosquitoes and Culicoides biting midges: vector range and the influence of climate change

“…Only 13 years ago, it was concluded that there was no strong evidence to show that climate change was exerting a demonstrable impact on vector-borne diseases, such as malaria, dengue, leishmaniosis and tick-borne diseases (50). In spite of the large amounts of data being gathered, we are still a long way from knowing whether insects and other organisms are responding and adapting to climate change and if such changes apply widely across taxa, space and time (51). The principal difficulty is the absence of long-term (>50 years) data sets, which means that we lack a strong baseline against which to compare and assess species responses to climate change (5).…”

Diamondback Moth, Plutella xylostella (L.) in Southern Africa: Research Trends, Challenges and Insights on Sustainable Management Options

“…Field population peaks, determined by both pheromone trap catches and crop infestation scouting, were observed in the warmer austral summer [19,22,49]. Regardless of the population source, high temperatures were shown to hasten development and thus shorten life cycles in P. xylostella [36,37]. However, temperature may differentially affect organisms, such that different insect pests (hosts) and their associated natural enemies may develop at different rates and thus affect host-prey/parasitoids synchronisation [26,33,50,51].…”

“…In SA, temperature is projected to increase by 1-3 • C by 2050 [45][46][47] and its effects are likely to be more pronounced in the drier tropics than the humid subtropics [8,9]. In laboratory experiments, DBM showed activity over a broad temperature range, measured as LLTs and ULTs [36,38]. This may mean that, under the currently projected climate change in SA, DBM pest status is likely to increase, exacerbating already failing management practices [18,25,48].…”

Additive and synergistic effects of land cover, land use and climate on insect biodiversity

“…Within the insects, we target the ants (Family: Formicidae), a ubiquitous and diverse insect group that has received relatively little climate change research (Andrew et al 2013a;Gibb et al 2015), and we do so through an investigation of communities rather than single species. Ant communities have a long history of use as indictors of disturbance (Andersen and Majer 2004;Solar et al 2016) and play crucial roles in ecosystem functioning on all continents except Antarctica; as invertebrate and seed predators, seed dispersers, detritivores, herbivore ''farmers'', in bioturbation and mutualisms, and as a food source for other invertebrates and vertebrates (Lach et al 2010).…”

“…Insect focused climate change research is however scant, especially so in Asia, Africa and Australasia, and in particular where habitats are modified and landscapes are fragmented. Available research has concentrated on changes in abundance and/or distribution shifts of single species due to climate change, most commonly butterflies in Europe (Wilson et al 2007;Felton et al 2009), or insects of concern to primary producers (Andrew et al 2013a).…”