Understanding how environmental conditions influence organismal performance requires linking physiological limits with the microclimates actually experienced by individuals. In mound-building termites, nest architecture can modify thermal exposure, yet its consequences for physiological and functional variation remain poorly understood. We combined experimental measurements of critical thermal maximum (CTmax), field measurements of mound microclimate, mechanistic estimates of operative body temperature, and analyses of morphological, enzymatic, and gut bacterial traits to examine responses of Cornitermes cumulans across a climatic gradient. At the Campinas site, mound interiors showed markedly lower thermal variation than ambient conditions, while modelled operative temperatures indicated positive thermal safety margins across the broader climatic gradient. Nevertheless, CTmax remained associated with regional climate, increasing with annual precipitation and decreasing with mean diurnal temperature range. Worker morphology also varied strongly with climatic conditions, while β-glucanase activity and gut bacterial richness were associated with different climatic drivers. Future projections indicated substantial reductions in thermal safety margins under SSP2–4.5 and SSP5–8.5 scenarios, with greater losses at lower latitudes and progressively smaller reductions toward higher latitudes. These findings suggest that mound-mediated buffering reduces direct exposure to thermal extremes without eliminating climatic effects on physiological and functional traits. Architectural niche construction may therefore generate a Bogert-like effect in which thermal buffering maintains current safety margins but does not fully protect colonies from future warming, particularly at lower latitudes.
Observing termite foraging in a natural setting is limited due to their cryptic nature, tunneling undetected through soil to discover cellulose food resources. Previous research including excavation, mark-release-recapture, and genetic fingerprinting in the field, as well as planar arenas in the laboratory has greatly advanced our understanding of the gallery system, colony territory areas, and tunnel geometry but still are limited due to experimental constraints. In this study, subterranean termite tunneling was observed in the field by casting termite foraging tunnels with zinc. A grid of wooden surveyor stakes was established and colonized by Formosan subterranean termites, Coptotermes formosanus. Additional auxiliary stakes were added two weeks before the casting date to compare established and newly discovered food resources. Stakes were removed and connecting tunnels were cast with zinc and excavated for measurements of tunnel number and area. Zinc successfully spread into adjacent tunnels in 27 stake casts and revealed oval, ribbon like tunnels of varying sizes with many complicated intersections. There was no significant difference in the number or area of connecting tunnels in established resources compared to newly discovered resources, likely because the wooden stakes were inserted into a preexisting network of termite tunnels in the area. This study visualized subterranean termite tunnels using zinc casting in the field and provided insight into their structure but also demonstrated congruency with laboratory planar arena observations.
Ant-mediated seed dispersal (myrmecochory) is a widespread mutualistic interaction between plants and ants in which ants gain food rewards for seed dispersal services. While the benefits to plants in myrmecochory are well-studied, less is understood about the benefits to ant partners, with particular regard to ant food choice and benefits to worker ants. Additionally, though ant chemical treatment of seeds within the nest has been proposed, insights into ant-produced chemicals are lacking, as well as how those chemicals impact seeds while undergoing ant handling. Here we investigate preference for different myrmecochorous seeds in the ant Aphaenogaster fulva, link preference to ant colony survival, explore chemical compounds present on the bodies of these ants, and assess whether these chemical compounds are transferred to seeds. We find that A. fulva seed preference, as measured by seeds taken into the ant nest, corresponds to seeds that result in higher colony survival. We have also identified the most abundant chemicals on different regions of the ant body, including several known alarm compounds (such as 3-octanone), the venom alkaloid anabaseine, several fatty acids, and a complex mixture of long-chain hydrocarbons, many of which have been previously identified in other ant genera. We additionally find minimal evidence that A. fulva transfers chemicals to seeds during handling (although some fatty acids may be transferred). By investigating ant preference, survival, and chemistry, we increase our understanding of the benefits to ants in myrmecochory, supporting the idea that ant benefits are not as clearcut as plant benefits. We also broaden the potential to explore chemical treatment of seeds in the ant nest environment.
Red wood ants (Formica rufa group) are key ecosystem engineers, but their populations are under threat due to habitat fragmentation. Although their foraging dynamics have been well studied, the causal link between the physical quality of transport infrastructure and colony-level development remains poorly understood. This study experimentally tests whether artificial, low-friction wooden trails can enhance nest growth and foraging efficiency in F. rufa and F. polyctena under field conditions. Over a three-year period (2023–2025), we monitored nest volume and foraging traffic (i.e. the transport of resources and workers) across multiple anthills in two distinct nest complexes. Our results demonstrate that colonies equipped with artificial trails exhibited a significant increase in nest volume compared to control colonies, with the most pronounced growth in the F. polyctena nest complex. This expansion was accompanied by higher worker activity and increased prey influx. Furthermore, the relationship between nest size and foraging intensity strengthened towards the end of the active season, suggesting improved functional integration of the transport system. These findings suggest that physical constraints of the natural forest floor act as a bottleneck for resource delivery. While the observed growth represents medium-term acceleration rather than a permanent change in the growth regime, artificial trails have proven to be an effective experimental tool. This approach offers practical insights for forest management and the conservation of declining red wood ant populations, as it has the potential to enhance their ecological resilience through infrastructure manipulation.
Aggression and defense in honeybees are crucial for deterring predators, sustaining colony homeostasis, and ensuring species reproduction. Studies have shown that aggressive behavior in insects is closely related to key biogenic amines, including octopamine (OA) and dopamine (DA). However, the specific role of OA in modulating honeybee aggression remains largely unknown. In this study, Apis cerana worker bees were injected with OA, an OA receptor agonist (amitraz), an OA receptor antagonist (mianserin), or DA. Workers from a foreign colony were introduced as intruders to quantify aggressive responses, thereby investigating OA's role in aggression. The results showed that injection of OA or OA receptor agonist increased aggression, whereas the OA receptor antagonist caused a reduction. Co-injection of agonist and antagonist abolished the agonist-induced increase, restoring aggression to control levels. DA injection also significantly elevated aggression. These findings demonstrate that aggression in A. cerana is regulated by both OA and DA, with OA acting through its specific receptor system and DA also contributing to the modulation of aggressive behavior.
