The frequency, duration, and co-occurrence of several environmental stressors, like heat waves and droughts, are increasing globally. Such multiple stressors may have compounding or interactive effects on animals, resulting in either additive or non-additive costs, but animals may mitigate these costs through various strategies of resource conservation or shifts in resource allocation. Through a factorial experiment, we investigated the independent and interactive effects of a simulated heat wave and water limitation on life-history, physiological, and behavioral traits. We used the variable field cricket, Gryllus lineaticeps, which exhibits a wing dimorphism that mediates two distinct life-history strategies during early adulthood. Long-winged individuals invest in flight musculature and are typically flight capable, whereas short-winged individuals lack flight musculature and capacity. A comprehensive and integrative approach with G. lineaticeps allowed us to examine if life-history strategy influenced the costs and cost-limiting strategies due to multiple stressors. Concurrent heat wave and water limitation resulted in largely non-additive and single-stressor costs to important traits (e.g., survival and water balance), extensive shifts in resource allocation priorities (e.g., reduced prioritization of body mass), and a limited capacity to conserve resources (e.g., heat wave reduced energy use only when water was available). Life-history strategy influenced the emergency life-history stage because wing morphology and stressor(s) interacted to influence body mass, boldness behavior, and immunocompetence. Our results demonstrate that water availability and life-history strategy should be incorporated into future studies integrating important conceptual frameworks of stress across a suite of traits—from survival and life history to behavior and physiology.

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Water bodies can mitigate urban heat island effects and allow terrestrial animals to access water during periods of insufficient precipitation. Because precipitation is expected to become increasingly scarce in many global regions, urban riparian areas in drylands may yield important insight into the dynamic role of water in terrestrial animal communities. Here, we first investigated the role of spatiotemporal variability in water availability in insect biomass and biodiversity in an urban riparian area—particularly, whether seasonality modulates the spatial effects of water availability. High water availability was characterized spatially by proximity to a river, and temporally by high-precipitation seasons. Second, we investigated whether the relationship between biomass and biodiversity shifts due to variation in water availability. We determined the biomass and biodiversity of an insect community across a riparian zone in Stockton, CA, USA, an urban drylands area characterized by hot, dry summers and cool, wet winters. Time (seasonality exhibiting dramatic variation in precipitation) exerted strong effects on ecological indices and a biodiversity-biomass relationship. Space (proximity to a fixed water source) had more modest effects on the community, and there was some evidence that space and time modulated the effects of one another on the community. Urban animal community dynamics may be more sensitive to larger-scale climate patterns than to local, landscape-level factors, and covariation between biomass and biodiversity may be influenced by resource (water) availability. Studying insect communities in the riparian zones of urban drylands may be critical to understanding how animal communities respond to a warmer, drier climate.