Complex responses of global insect pests to climate change

Abstract

<jats:title>Abstract</jats:title><jats:p>Insect pests strongly affect the productivity and profitability of agriculture and forestry. Despite the well-known sensitivity of insects to abiotic effects such as temperature, their potential responses to ongoing climate change remain unclear. Here we compile and review documented climate change responses of 31 of the globally most impactful phytophagous insect pests, focussing on species for which long-term, high-quality data are available. Most of the selected species show at least one response affecting their severity as pests, including changes in geographic range, population dynamics, life-history traits, and/or trophic interactions. Of the studied pests, 41% only show responses that are linked to increased pest severity, 4% only show responses of decreased severity, whereas importantly 55%, the majority of studied pests, show mixed responses including both increased and decreased severity under ongoing climate change. Variability in impact is further supported by a thermal sensitivity analysis showing little benefit of climate warming in relation to the optimal developmental temperatures for the majority of these pests under both current climate and future projections. Overall the results show that calculating the net effect of climate change on phytophagous insect pest impact is far from straightforward. The documented variation in responses, e.g. between agricultural and forest pests, indicates that efforts to mitigate undesirable climate change effects must target individual species, taking into account the complex ecological and evolutionary mechanisms underlying their responses.</jats:p>

The Effect of Oxygen Limitation on a Xylophagous Insect’s Heat Tolerance Is Influenced by Life-Stage Through Variation in Aerobic Scope and Respiratory Anatomy

“…Understanding insect responses to temperature is therefore crucial in estimating how global warming will affect terrestrial arthropods (Bale et al, 2002; Huey et al, 2012). This is particularly true for insect pests, whose distribution and population dynamics are likely to be modified with changing climate (Battisti and Larsson, 2015; Lehmann et al, 2019a). For these reasons, estimating thermal limits is critical, since they represent the environmental limits of key traits, such as activity, survival, development and reproduction of ectothermic organisms (Angilletta, 2009).…”

Additive genetic variance for traits least related to fitness increases with environmental stress in the desert locust,Schistocerca gregaria

“…Although additive genetic variation was not visible for most morphological traits involved in phase polyphenism under standard conditions, ecologically relevant cold stress released cryptic genetic variation for most of them, including the most discriminative of all morphometric phase ratios (i.e., ratio of the length of the hind femur to the maximum width of the head). Traits related to phenology have already been detected to respond to ongoing climate change in insect populations (Lehmann et al., 2020 ). Accordingly, development time was the single life history trait to unmask genetic variation in the desert locust, exposing it to stronger selection under environmental thermal stress, a potentially crucial driver of phase polyphenism evolution in nature.…”

“…In face of such a heat stress, the species had evolved an upper thermal limit for survival of 51℃ and multiple thermoregulatory behaviors to cool down (e.g., stilting on the hot ground, moving to the shade, and perching on shrubs; Maeno et al., 2021 ). Since ongoing global warming may increase the frequency, intensity, and/or duration of daily heat waves (IPCC, 2013 ), next evaluations of its influences in the desert locust should be conducted under opportunities for microenvironments and under fluctuating temperatures, which explore large daily temperature change (Lehmann et al., 2020 ).…”

The effect of resource depletion on the thermal response of mosquito population fitness

“…warming (e.g., due to increases in decomposition and microbial growth rates), its regulatory effect on population growth and abundance could be relaxed through increased juvenile development and adult recruitment rates. Indeed, increased resource availability with warming could contribute to the expansion of disease vectors and other invasive pest species into regions that were previously prohibitive by broadening rm's thermal niche width (Amarasekare & Simon 2020;Lehmann et al 2020). On the other hand, evidence from our high resource concentration treatments (e.g., a lower Topt at 0.733 than at 0.367 mg ml -1 ) may suggest that warming could have a negative impact on population growth by causing resources to be overabundant, which could lead to eutrophication and hypoxia in aquatic environments (Liikanen et al 2002).…”

“…As a result, the combined effects of climatic warming and decreased resource availability could contribute to the contraction of species range boundaries. This effect could simultaneously decrease the burden of vector-borne diseases and agricultural pests but increase the extinction risk of vulnerable species (Amarasekare 2019;Lehmann et al 2020). Conversely, concurrent increases in temperature and resource availability with climatic warming could have the opposite effect by optimising rm thus, promoting the invasion of tropical taxa into temperate habitats (Amarasekare & Simon 2020).…”