Heat wave effects on the behavior and life-history traits of sedentary antlions

Abstract

Research on the behavioral responses of animals to extreme weather events, such as heat wave, is lacking even though their frequency and intensity in nature are increasing. Here, we investigated the behavioral response to a simulated heat wave in two species of antlions (Neuroptera: Myrmeleontidae). These insects spend the majority of their lives as larvae and live in sandy areas suitable for a trap-building hunting strategy. We used larvae of Myrmeleon bore and Euroleon nostras, which are characterized by different microhabitat preferences—sunlit in the case of M. bore and shaded in the case of E. nostras. Larvae were exposed to fluctuating temperatures (40 °C for 10 h daily and 25 °C for the remaining time) or a constant temperature (25 °C) for an entire week. We found increased mortality of larvae under heat. We detected a reduction in the hunting activity of larvae under heat, which corresponded to changes in the body mass of individuals. Furthermore, we found long-term consequences of the simulated heat wave, as it prolonged the time larvae needed to molt. These effects were pronounced in the case of E. nostras but did not occur or were less pronounced in the case of M. bore, suggesting that microhabitat-specific selective pressures dictate how well antlions handle heat waves. We, thus, present results demonstrating the connection between behavior and the subsequent changes to fitness-relevant traits in the context of a simulated heat wave. These results illustrate how even closely related species may react differently to the same event.

Past thermal conditions affect hunting behaviour in larval antlions

“…Consequently, we consider that the effects of differential acclimatization capacity were not responsible for the observed differences in trap building among our treatments. We stress that considering the long developmental time in antlions and wormlions, their experiences and acclimatization abilities need further research [ 30 ].…”

“…In species that prefer shaded and sheltered locations, including E. nostras used in the present study, the temperature effects on performance are well known [ 31 , 32 , 55 ], even if they are less dramatic than those in other species inhabiting open, sun-exposed locations (see [ 56 , 57 ]). It is very likely that in other more thermally tolerant species, such as the very thermophilic Myrmeleon bore [ 30 , 33 ], the effects of previous thermal exposure would be less pronounced. The extent to which our results are relevant to other sit-and-wait predators thus needs more comparative research attention.…”

“…Here, we performed a laboratory experiment that aimed to temporarily challenge larvae of Euroleon nostras antlions to either mild or harsh thermal stress and evaluated how the two types of experience affected subsequent trap construction under thermally non-challenging conditions. There is evidence suggesting that antlions originating from shaded areas in nature, such as our study species, might be more vulnerable to thermal challenges than antlions from open areas, such as Myrmeleon bore [ 30 ]. Nevertheless, antlions generally display extraordinary heat tolerance, and their foraging performance increases linearly with temperature [ 15 , 31 – 33 ].…”

Thermal and Oxygen Flight Sensitivity in Ageing Drosophila melanogaster Flies: Links to Rapamycin-Induced Cell Size Changes

“…Thermal and oxygen conditions also vary on a geological time scale and a geographic scale (e.g., latitudinal and elevational gradients), so our results help to better understand the selective pressures imposed on flying insects by spatiotemporal environmental gradients. Thus, our study enters the discussion of the biological consequences of anthropogenic environmental changes, which involve not only the effects of rising global mean temperatures but also the effects of the increased frequency of locally appearing heat waves or heat islands established by urban activities [ 136 , 137 , 138 , 139 , 140 ]. To date, mainstream research addressing human impacts on ectotherms has focused on connections between environmental changes and species’ geographic distributions, survival and body sizes (e.g., [ 135 , 141 , 142 , 143 , 144 , 145 , 146 ]), but our study suggests that this perspective should also include the connections between cell-size life strategies and organismal performance in the changing world.…”

Integrating animal behaviour into research on multiple environmental stressors: a conceptual framework

“…Life stages vary in their vulnerability to different combinations of stressors, and this varies across taxa (Stoks 2001;Rohr et al 2011;Przeslawski et al 2015;Watson et al 2018;Tran et al 2020). Yet, for many taxa, when juveniles divert energy to dealing with multiple stressors rather than development, this results in particularly strong negative effects, involving both increased sublethal effects and higher mortality (Byrne & Przeslawski 2013;Przeslawski et al 2015;Lange et al 2018;Miler et al 2020). For example, echinoderm larvae can show elevated mortality, impaired development and signs of metabolic depression following exposure to heightened temperature and p CO 2 (Byrne & Przeslawski 2013;Przeslawski et al 2015).…”