Case‐building of some Trichoptera larvae in experimental conditions: Selectivity for calcareous and siliceous grains

Abstract

The ability of some caddisflies to select calcareous and siliceous grains during case-building was tested in experimental conditions. This investigation was carried out on Hydropsyche morettii, Limnephilus flavicornis, Micropterna sequax, and Sericostoma pedemontanum; the last of these was collected in a habitat with prevalently calcareous substratum, whereas the remaining species were from marly-arenaceous ones. Larvae were provided with a substratum mixture made up of travertine and quartzite grains (1.0-1.5 mm in size forming a 1-cm-thick substratum). Apart from H. morettii, which only picks up grains in its pupal stage, the remaining species are case-builders during their larval stage. After being removed from their original case, larvae were reared in Petri dishes kept at a constant temperature of 23° C. Video camera recordings, coupled with the analysis of the number and typology of the grains incorporated into each reconstructed case, gave evidence that evicted individuals exhibited a significant preference in the picking up of grains. The Tukey test indicated, with the exception of H. morettii, a significant preference for travertine grains. Sericostoma pedemontanum preferentially selected travertine grains when reared on a mixed substratum, but it built a case using quartzite when provided exclusively with these grains. This demonstrates that the ancestral impulse to construct a protective shield prevails over the nature of the material. The preferential choice of travertine grains could be due to certain mechanical and chemical silk/grain interaction factors.

Microplastics of different characteristics are incorporated into the larval cases of the freshwater caddisfly Lepidostoma basale

“…leaves; Sheath et al 1995, Moretti et al 2009 and abiotic (e.g. sediment grains; Gaino et al 2002, Okano et al 2012) materials, and some species use both material types (Hansell 1972). Different caddisfly species differ in their preferences for certain case-building materials (Hanna 1961).…”

Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials

“…For humans, the distribution and design of prehistoric tools appear to be correlated with both the quality and quantity of available raw materials [ 38 ], although recent experiments revealed that it is possible, in principle, to produce similar stone tools from a range of stone types [ 39 ]. Amongst non-human animals, experimentally-provided raw materials have been shown to induce structural differences (compared to wild type) in diverse artefacts, for example, in the protective cases of caddis fly larvae (Trichoptera), when produced from un-preferred raw materials [ 40 ], or in the nests of zebra finches ( Taeniopygia guttata ), when built from floppy pieces of string [ 41 ]. Given the potentially strong links between raw materials, behaviour and artefacts, and ultimately, their combined effects on fitness components, it is surprising that this topic has received so little attention to date.…”

Mineral grains in caddisfly pupal cases and streambed sediments: Resource use and its limitation through conflicting resource requirements

“…If the available grain sizes are too different from the preferred ones or mineral grains are not available in such experiments, the larvae build irregular silk constructions, or, if provided, some (but not all) species use plant material of appropriate size (Haller 1948;Hanna 1961;Tolkamp 1980). In addition, larvae that prefer a particular mineral material (e.g., travertine) may switch to a different mineral (e.g., quartzite) if the preferred one is unavailable (Gaino et al 2002).…”