Multiple mechanisms in which agricultural insects respond to environmental stressors: canalization, plasticity and evolution

Abstract

Insects are a paramount component of biodiversity in terms of taxonomic richness, ecological functions and ecosystem services. However, many human activities have negative consequences on such organisms, causing changes in their morphology, physiology, behaviour, and even causing mass deaths leading to the well-recognized insect decline phenomenon. Although the effects of some environmental stressors (e.g. global warming and pesticides) on insect biology are fairly well understood, there is a plethora of stressors that that have only recently been considered. Additionally, although the exposure to multiple stressors is a common scenario in natural conditions, our knowledge on insect responses in this regard is still incipient. Knowledge that is in much need to inform policy makers in the fight against global change. Here, a short review on prominent environmental stressors, and the known responses that insects may exhibit, which are summarized as canalization, plasticity and evolution is provided. Furthermore, an outlook and recommendation for future studies aiming to elucidate the effects of environmental stressors (both lone and mixed) on insect biology is given. This manuscript advocates for controlled (lab or semi-field) manipulative experiments that implement realistic environmental conditions and that ideally combine several stressors.

Life‐stage‐related desiccation and starvation resistance in the biological control agent Neolema abbreviata

“…In nature, plants and insects often experience multiple environmental stressors during their lifetime which may have detrimental effects on their physiological sensitivity, survival, and development (Côté et al, 2016; Gutierrez, 2020; Karthik et al, 2021). These stressors are primarily driven by rapid and extreme changes in environmental factors such as solar radiation, temperatures, carbon dioxide levels, and seasonal shifts in precipitation patterns (Karthik et al, 2021).…”

“…Like desiccation resistance, starvation resistance has also been reported to vary across age (Chidawanyika et al, 2017), sex (Scharf et al, 2016), and species (Zhang et al, 2019). Depending on their frequency, magnitude, duration, and intensity, environmental stressors may activate various behavioural, morphological, and physiological responses in insects (Gutierrez et al, 2020). Behaviourally, insects can seek cooler microhabitats, restrict activity periods or migrate to favourable habitats (Kleckova & Klecka, 2016).…”

“…Behaviourally, insects can seek cooler microhabitats, restrict activity periods or migrate to favourable habitats (Kleckova & Klecka, 2016). Physiologically, some insects can employ canalization, a form of plasticity where they maintain consistent phenotypes regardless of environmental stressors experienced (Gutierrez et al, 2020). In addition, some use genetic adaptation which involves changes in allele frequency across generations (Karl et al, 2014) and within-generational phenotypic plasticity where a single genotype can morphologically, biochemically, and physiologically remodel an organism's phenotype under heterogeneous environments (Whitman & Ananthakrishnan, 2009;Sgrò et al, 2016).…”

Cross‐protection interactions in insect pests: Implications for pest management in a changing climate

“…As such, single stressor studies continue to be foundational to our understanding of generalized responses to a wide range of stressors 109–112 . Yet, despite its usefulness, single stress frameworks may not be as relevant to the study of insect pests that are regularly exposed to a combination of physical, biotic and chemical stressors that can interact in ways that enhance stress tolerance 113–115 . Such interactions can result in additive and non‐additive effects on insect performance and survival 24,25,52 .…”

The kairomone p-anisaldehyde increases the effectiveness of sticky traps for capturing Neohydatothrips signifer (Insecta: Thysanoptera) in yellow passion fruit (Passiflora edulis) crops

“…However, the cryptic behavior of thrips hampers the action of insecticides (i.e., they are harder to reach) (Kirk et al, 2021). Furthermore, it is well known that misuse of synthetic pesticides in agricultural environments may disrupt needed ecological interactions (i.e., biological control by natural enemies) and induce insecticide-resistance evolution (Desneux et al, 2007;Gutiérrez, 2020;Mahmood et al, 2016;Mouden et al, 2017). Additionally, the utilization of broadspectrum insecticides is not advisable in yellow passion fruit crops as P. edulis is strictly self-incompatible and relies heavily on bee pollination (Jaramillo et al, 2009;Junqueira et al, 2013).…”