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A - C absolute weight-increase in g and D - F weight-increase relative to dryweight for beam geometry; humidification (relative humidity in air) and moistening (water dipping) of Po. alba, P. radiata and E. regnans over time. Average values are marked by a solid thick line. Period I describes the process of saturation at 80% RH (28 ºC), period II is the increase in weight owing to the wood being dipped in water and in period III the wood is oven-dried again

Animals use cues to find their food, in microhabitats within their physiological tolerances. Termites build and modify their microhabitat, to transform hostile environments into benign ones, which raises questions about the relative importance of cues. Termites are desiccation intolerant and foraging termites are attracted to water, so most research has considered moisture to be a cue. However, termites can also transport water to food, and so moisture may play other roles than previously considered. To examine the role of moisture, we compared Coptotermes acinaciformis termite foraging decisions in laboratory experiments when they were offered dry and moist wood, with and without load. Without load, termites preferred moist wood and ate it without any building, whereas they moistened dry wood after wrapping it in a layer of clay. For the ‘With load’ units, termites substituted some of the wood for load-bearing clay walls, and kept the wood drier than on the unloaded units. As drier wood has higher compressive strength and higher rigidity, it allows more of the wood to be consumed. These results suggest that moisture plays a more important role in termite ecology than previously thought. Termites manipulate the moisture content according to the situational context and use it for multiple purposes: increased moisture levels soften the fibre, which facilitates foraging, yet keeping the wood dry provides higher structural stability against buckling which is especially important when foraging on wood under load.

Animals use cues to find their food, in microhabitats within their physiological tolerances. Termites build and modify their microhabitat, to transform hostile environments into benign ones, which raises questions about the relative importance of cues. Termites are desiccation intolerant and foraging termites are attracted to water, so most research has considered moisture to be a cue. However, termites can also transport water to food, and so moisture may play other roles than previously considered. To examine the role of moisture, we compared Coptotermes acinaciformis termite foraging decisions in laboratory experiments when they were offered dry and moist wood, with and without load. Without load, termites preferred moist wood and ate it without any building, whereas they moistened dry wood after wrapping it in a layer of clay. For the ‘With load’ units, termites substituted some of the wood for load-bearing clay walls, and kept the wood drier than on the unloaded units. As drier wood has higher compressive strength and higher rigidity, it allows more of the wood to be consumed. These results suggest that moisture plays a more important role in termite ecology than previously thought. Termites manipulate the moisture content according to the situational context and use it for multiple purposes: increased moisture levels soften the fibre, which facilitates foraging, yet keeping the wood dry provides higher structural stability against buckling which is especially important when foraging on wood under load.

Termite mounds built by representatives of the family Termitidae are among the most spectacular constructions in the animal kingdom, reaching 6–8 m in height and housing millions of individuals. Although functional aspects of these structures are well studied, their evolutionary origins remain poorly understood. Australian representatives of the termitid subfamily Nasutitermitinae display a wide variety of nesting habits, making them an ideal group for investigating the evolution of mound building. Because they feed on a variety of substrates, they also provide an opportunity to illuminate the evolution of termite diets. Here, we investigate the evolution of termitid mound building and diet, through a comprehensive molecular phylogenetic analysis of Australian Nasutitermitinae. Molecular dating analysis indicates that the subfamily has colonized Australia on three occasions over the last approximately 20 Myr. Ancestral-state reconstruction showed that mound building arose on multiple occasions and from diverse ancestral nesting habits, including arboreal and wood or soil nesting. Grass feeding appears to have evolved from wood feeding via ancestors that fed on both wood and leaf litter. Our results underscore the adaptability of termites to ancient environmental change, and provide novel examples of parallel evolution of extended phenotypes.

Termite mounds built by representatives of the family Termitidae are among the most spectacular constructions in the animal kingdom, reaching 6–8 m in height and housing millions of individuals. Although functional aspects of these structures are well studied, their evolutionary origins remain poorly understood. Australian representatives of the termitid subfamily Nasutitermitinae display a wide variety of nesting habits, making them an ideal group for investigating the evolution of mound building. Because they feed on a variety of substrates, they also provide an opportunity to illuminate the evolution of termite diets. Here, we investigate the evolution of termitid mound building and diet, through a comprehensive molecular phylogenetic analysis of Australian Nasutitermitinae. Molecular dating analysis indicates that the subfamily has colonized Australia on three occasions over the last approximately 20 Myr. Ancestral-state reconstruction showed that mound building arose on multiple occasions and from diverse ancestral nesting habits, including arboreal and wood or soil nesting. Grass feeding appears to have evolved from wood feeding via ancestors that fed on both wood and leaf litter. Our results underscore the adaptability of termites to ancient environmental change, and provide novel examples of parallel evolution of extended phenotypes.

As eusocial and wood-dwelling insects, termites have been shown to use vibrations to assess their food, to eavesdrop on competitors and predators and to warn nest-mates. Bioassay choice experiments used to determine food preferences in animals often consider single factors only but foraging decisions can be influenced by multiple factors such as the quantity and quality of the food and the wood as a medium for communication. A statistical analysis framework is developed here to design a single bioassay experiment to study multifactorial foraging choice (Pinus radiata) in the basal Australian termite species Coptotermes (C.) acinaciformis (Isoptera: Rhinotermitidae). By employing a correlation analysis, 17 measured physical properties of 1417 Pinus radiata veneer discs were reduced to five key material properties: density, moisture absorption, early wood content, first resonance frequency and damping. By applying a fuzzy c-means clustering technique, these veneer discs were optimally paired for treatment and control trials to study food preference by termites based on these five key material properties. A multifactorial analysis of variance was compared to a permutation analysis of the results indicating for the first time that C. acinaciformis takes into account multiple factors when making foraging decisions. C. acinaciformis prefer denser wood with large early wood content, preferably humid and highly damped. Results presented here have practical implications for food choice experiments and for studies concerned with communication in termites as well as their ecology and coevolution with trees as their major food source.