Aquatic Entomology Lecture 6 - Feeding devices and foraging strategies

What are the foods of aquatic insects (4)

• Animal Prey

  • Generalist

• Large Plants

  • Macrophytes and mosses

  • Herbivory is not common

• Phytoplankton

  • Eat filamentous and attached algar

  • Biofilm

• Detritus

  • Dead part of plants (fungi and bacteria)

    • > 1 mm = COURSE particulate organic matter (CPOM)

    • < 1 mm = FINE particulate organic matter (FPOM)

What are the functional feeding groups (7)

• Predators

  • Engulfers

  • Piercers

• Parasites

• Shredders, chewers, and xylophages

• Algal piercers/bursters

• Grazers

• Collecter-gatherers

• Filter feeders

Predators

Animals that attack and consume other animal prey, typically alive when attacked

• Engulfer

• Piercing/sucking

Engulfers (Definition, adaptions 3)

Swallow prey WHOLE or large parts of it

1.) Mandibles for grasping and tearing

• elongated and sickle shaped, sharp apical teeth and serrated inner margins

2.) Other modified mouth parts

• Transferring prey to mouth

• Stabbing and holding prey (stoneflies) LABIUM

• Prehensile mouth (odonates)

• Freshwater sponge specialist

3.) Net forming engulfers

• Trichoptera

Piercer/suckers (definition, orders 3, organisms 3)

Penetrate organism, INJECT extraoral enzyme, suck up juices

NCH

Neuroptera

• Osmylidae

  • Paralyzes prey

• Sisyridae (spongillaflies)

  • Sponges

• Coleoptera

  • Dytiscidae

• Hemiptera

  • All BUT corixidae have LONG STYLUS MOUTHPARTS

Other adaption for predators

Raptorial or prehensile appendages

• Diptera: Chaoboridae: Chaoborus

• Trichoptera: Nepidae

• Hemiptera: Belostimatidae

Parasites (definitations)

Both endo- and ectoparasites which live off bodily fluids of the host

endoparasite

Lives INSIDE the host

Hymenoptera: wasps

ectoparasites

Lives OUTSIDE the host

Hymenoptera, Trichoptera, and coleoptera

• Mouth part adapted for piercing skin and tapping into body tissues

Shredders, chewers, and xylophages

Chew, mine or gouge plant tissues (living or dead)

• mouth parts suited for scavenging

• Mandibles used for cutting (short and stout) and molars used for grinding

Shredding living

• Lepidoptera and coleoptera

Shredding detritus

• Consume CPOM and wood

• Wood eaters: xylophagy: Diptera, trichoptera, coleoptera, and plecoptera

Xylophagy (4 orders)

wood eaters

1.) Diptera

2.) Trichoptera

3.) Coleoptera

4.) Plecoptera

Algal piercers/bursters

Pierce algal cells and consume the cell content

Cutting mandibles that break open algal cells and eats the contents

• Haliplidae (coleoptera)

  • Peltodytes/Haliplus immaculicollis

    • CHELATE forelegs grasp filamentous algae and push it to break individual algal cells

• Hydroptilidae (trichoptera)

  • Hydroptilidae

    • Asymmetric mandibles used to grasp and puncture the cells

Grazers

Remove attached biofilms (algal filaments, single-celled algae, fine detritus)

• Adapted mouthparts across the surface

  • Brushes, rakes, combs, brooms, gouges, and excavators used for scraping and collecting

  • Mouthparts transport the detached bio

  • Detached biofilm needs to be grounded up in mouth then separated from excess water

EXAMPLE: Rhithrogena pellucidula (Ephemeroptera: Heptageniidae)

• Brushes on labia

• Use comb to remove stuff from brushes

Collecter-gathers

Feed on CPOM, algae and their associated microorganisms on sedimented or deposited on various surfaces

• Overlap in diet with grazers

EXAMPLES:

• Stenocron interpunctatum (Ephemeroptera: Heptageniidae)

  • Brushes NOT scapes loose material with labium and maxiilae

• Chironomidae

  • Picks up individual particles or clusters of particles

Filter feeders

Collects FPOM particles from water column

• Location matters

  • In current: organisms sedentary

  • In standing water: mobile in water column and actively sweep particles into mouth or tube dwellers that create current

• Size of particle > what the particle is

• Can filter with body parts OR tubes/burrows/nets

Filtering with body parts

Standing water

• Mosquitoes

  • Mouthparts covered in brushes, combs, and sweepers

  • Move mouthparts and contract muscles to create current which carries particles into the mouth

• Running water

  • Filtering fringes on mouth parts or legs

    • Ephemeroptera: Trcorythus, Murphyella, Oligneurilla, Isonychia, and coloburiscoides

    • Trichoptera: Oligoplectrum and Branchycentrus

    • Diptera: Simulidae

Filtering with tubes/burrows/nets

Tube/burrow

• Diptera: Chironomidae

  • Constructs catchnets across tubes

    • Running water: catches in net

    • Standing water: creates current

  • Ephemeroptera: Polymitracyidae

    • Beat abdominal gills to create current and filters with brushes on forelegs and mandibles

Net

• Trichoptera: Hydropsychidae

  • In fast flowing water

  • Contruct large tube where larva sits and large vestibule that is perpendicular to the flow. Forelegs and mandibles pick off particles and sort them edible or inedible.