Key physical wood properties in termite foraging decisions

Abstract

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.

Termites manipulate moisture content of wood to maximize foraging resources

“…alba, Pi. radiata and E. regnans which had different densities and moisture absorption coefficients and compressive strengths [23]. Only using three 'legs' made of different wood species enabled accurate determination of the load and the foraging preferences.…”

Chemical constituents of tropical woods and resistance to the invasive drywood termite Cryptotermes brevis

“…These findings suggest that the levels of wood chemical constituents in tropical wood spe- between the wood chemical constituents and termite colonization and losses were not significant leading us to reject our initial hypothesis of the involvement of wood chemical constituents on termite resistance, even if secondary. Thus, the wood physical properties, hardness and mainly density, remain the sole recognized determinants of wood resistance to the West Indian drywood termite (Cosme et al, 2018), and also for other termite species (Oberst et al, 2018).…”

“…Wood type and size affect conspecific interactions and production of secondary reproductives of drywood termites (Evans et al, 2011;Korb, 2006), as do wood anatomy and volatile emissions (Himmi et al, 2016;Scheffrahn & Rust, 1983;Xu, Feng, Zhong, Zheng, & Chen, 2015). Curiously, resistance of tropical wood and its underlying causes were seldom investigated and the studies carried out so far focus on recognizing preferences and mainly by subterranean termite species with few exceptions (Cornelius & Osbrink, 2015;Lee, Bardunias, Su, & Yang, 2008;Lee & Forschler, 2016;Manzoor, Abbas, & Latif, 2015;Oberst, Lai, & Evans, 2018;Rust & Reierson, 1977;Rust & Su, 2012;Scheffrahn & Rust, 1983). Nonetheless, varied resistance to the West Indian drywood termite exists (Cosme, Haro, Guedes, Della Lucia, & Guedes, 2018;Gonçalves & Oliveira, 2006;Oliveira, Paes, & Vidaurre, 2017), and the wood physical properties, namely hardness and specially density, are important determinants of colonization and wood consumption by this invasive pest species (Cosme et al, 2018).…”

Revisiting stigmergy in light of multi-functional, biogenic, termite structures as communication channel

“…In fact, most termite defensive action originates from passive means by staying camouflaged (including avoidance of detection [crypsis] and recognition [masquerade] [148] ) and cryptic, hidden and being protected by the mound and clay galleries or blocking passageways using e.g. sclerified heads [34] , [36] , [70] , [149] , [150] . Other geometric constraints are narrowing corridor systems to allow only termites to pass through one at a time such as those often found close to the royal cells [36] or also material partitions advantageous for the royal pair [151] for the drywood termite Incisitermes minor .…”

“…There is increasing evidence that termites us other information. Not visual information as termites are blind and there is no evidence that termites perceive drumming signals via airborne sound [149] , [185] , [186] , [187] . Termites have been found to communicate complex information using micro-vibrations (biotremology), an archaic and largely neglected, signalling modality [13] , [48] , [50] , [57] , [188] , [189] .…”