Trichoptera: Tube-Dwelling Insects and Their Diverse Habitats - Prof. John Abbott, Study notes of Entomology

Download Trichoptera: Tube-Dwelling Insects and Their Diverse Habitats - Prof. John Abbott and more Study notes Entomology in PDF only on Docsity! Tube Making • Construct branching tubes in the sediment using silk – rigid enough to remove intact • bring food in by undulating body • Phylocentropus (Dipseudosidae) Portable Case-makers • variety of portable cases – vegetable – mineral • material held together by silk • Saddle Case Makers (Glossosomatidae) • Purse Case Makers (Hydroptilidae) • Snail Case Makers (Helicopsychidae) • Flange (Mummy) Case Makers (Molannidae) • Tube Case Makers (Brachycentridae, Limnephilidae, Lepidostomatidae, Leptoceridae, Odontoceridae, Phryganeidae, Sericostomatidae) Case diversity solves a variety of problems • Streamlining – reduction of external water resistance • ballast • buoyancy • camouflage • internal water circulation • protection from predators Lentic Habitats Cases & Respiration • Case helps larva control current – serves as a conduit for respiratory current • Cases helped open lentic habitats – another consequence of silk production 3 humps on abdominal segment 1 maintain space between larva & case. Spicipalpia (Closed-Cocoon Makers) • apical seg. of maxillary & labial palps with small apical spicule Trophic Roles • Unlike Lepidoptera larvae, which are predominantly terrestrial herbivores – Trichoptera larvae, assume most trophic roles, BUT they are by far primarily detritivores • Adults only take fluids Herbivores • Shredders...feeding on living vascular hydrophytes and filamentous algae – Brachycentridae (Eobrachycentrus, Micrasema) – Hydroptilidae (Hydroptilinae) – Leptoceridae (Triaenodes) – Phryganeidae Shredders-Detritivores • Detritivores feeding on pieces of decomposing vascular plant tissue and associated microflora – Beraeidae – Calamoceratidae – Lepidostomatidae – Limnephilidae – Odontoceridae – Phryganeidae – Sericostomatidae Predators • Hydropsychidae • Leptoceridae (Ceraclea, Oecetis) • Molannidae • Phyganeidae • Polycentropodidae (Nyctiophylax, Polycentropus) • Rhyacophilidae Pupae • When larval growth is complete; pupal case is constructed • Some species are able to aestivate 2-3 months in this stage • Mandibles present but non-feeding • Natatorial legs • Taxonomically important (metamorphotype) – Leptoceridae tend to flush exuviae out before making pupal case Adult • mouthparts reduced, – maxillary and labial palps are prominent • compound eyes well- developed – ocelli may or may not be present • forewings longer than the hind wings • tibial spurs on legs conspicuous Wings held roof-like when folded over the body wings and the body covered with setae, or hairs Reproduction • Mate location – pheromones, encounter sites (swarming), vibrational • Copulation – male mounts female – then turns to face opposite direction • Most mating/oviposition activities occur during early morning or pre-dusk periods Oviposition • Habits vary – scatter eggs over the surface of the water – actually enter the water to oviposit on specific objects – deposit their eggs on objects protruding from the water or on overhanging vegetation – may be laid singly in strings or as a rounded egg mass • masses (30 to several hundred eggs) may be spherical, elliptical, doughnut shaped or flat with eggs arranged in a spiral pattern. Significance • No serious pests • Larvae are beneficial/adults may be considered nuisance • Adults attracted to lights in large numbers • 1901 Pan-American Exposition in New York • Larvae play important functional role in ecosystems • Typically sensitive to pollution (EPT) • Fly fishing Life History • In North America, as many as 6 (moth) families have some association with aquatic environments • Best exemplified in the Pyralidae – some undergo egg, larval & pupal development in the water – Acentria nivea, brachypterous females spends life in water • larval habits include leaf mining, stem or root boring, foliage feeding & feeding on flower or seed • some (Cosmopterigidae) make Trichoptera-like cases Pyralidae • larvae & pupae occur in a variety of aquatic habitats: – lakes, deep & fast-flowing streams, hot springs, intermittent streams, etc... • most are scrapers, feeding on algae & diatoms on the surfaces of rocks & submerged objects x c 3 —] Coleoptera Suborders Adephaga Polyphaga Distinguishing Features of Larvae • Most elongate and cylindrical • Head distinct • No wing pads • Most with three pair of true legs • Generally lack structures projecting from abdomen laterally • No prolegs or long tapering filaments from abdomen Distinguishing Features of Adult • Short to stocky, cylindrical to oval • Front wings modified into elytra and meet in a straight line medially • Hind wings membranous and longer than front wings • Antennae typically long and filamentous • Legs variously modified