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Entomology > Detritivory > Flashcards

Detritivory Flashcards

1
Q

what is a detrivore

A

a type of decomposer which consumes decaying plant or animal material as well as faeces

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2
Q

what are the functional groups of detritivores and how can they be separated

A

1) Dung and xylophagous beetles
2) mosquitos, dung and carrion flies
3) termites and cockroaches

= seperated into additional functional groups based on their decomposition processes

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3
Q

outline the general functional groups of decomposers

A

1) coarse and fine comminuters - breaakd down material into smaller pieces
2) xylophages - specalist wood feeders
3) coprophages - feed on faeces of larger species or re-ingest their own
4) necrophages - break down animal carcasses

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4
Q

outline what comminuters do

A

responsible for the fragmentation of large detrial materian into finer particles whcih can then be processed by fin comminuters and other saprophytic microorganismsms
= contirbute to lead litter decay and increase overall decay rate therefore are vital for nutrient cycling and soil production

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5
Q

give some examples of coarse and fine comminuter species

A

1) Ants and termites (Blattodea), earwigs and beetles = terrestrial coarse
2) mayflies and stone flies = aquatic corase

3) mayflies, caddisflies and elmid beetles = aquatic fine

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6
Q

outline what a xylophage is

A

they are a diverse group and specialised to excavate and fragment woody litter
- most feed on fungal-colonised wood or have mutuallistic in/external fungi, bacteria or protozoa which are needed to digest the cellulose in wood

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7
Q

give some examples of species which are xylophages

A
  • Zygentoma - Bristletails
  • Blattodea – termites and cockroaches
  • Coleoptera – tree-fungus beetles to longhorn
    beetles, elmid beetles (aquatic)
  • Diptera – pomace flies and craneflies (aquatic)
  • Hymenoptera – horntails and ants (Camponotus)
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8
Q

outline the challenges of xylophagy

A

HARD TO DIGEST = wood is 90% cell walls made of lignin, cellulose and hemi-cellulose which requires alot of enzymes to digest

TISSUE TYPE AND DEGREE OF FUNGAL DECAY AFFECT NUTIRITONAL VALUE OF WOOD = inner bark, cambium zone, sap wood and heart wood all have different nutritional values

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9
Q

outline nutritional value in different tissues of wood for xylophages

A

Inner bark = living cells rich in sugar
* Cambium zone = like inner bark with
greater concentration of proteins
* Sapwood = fully developed cell walls –
living and dead
* Heartwood = dead cells

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10
Q

what are saproxylic insects

A

specialised xylophages invloved in or dependant on wood decay
= IMPORTANT FOR DECOMPOSITION PROCESSES AND RECYCLING OF NUTRIENTS IN ECOSYSTEMS

  • pure dead wood = not sufficient food source = no nutrition so use fungi as source of nutrients
  • nutrients needed for insect development are provded by fungi
  • at different decay stages fungi colonisations change
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11
Q

give some examples of saproxylic insects

A
  • Sap: Diptera, Coleoptera larvae - suck or
    filter fluid
  • Inner bark: Coleoptera larvae – often
    quickly colonised by fungi
  • Sapwood/heartwood: Coleoptera,
    Hymenoptera, Lepidoptera, Diptera –
    often have associations with fungi and
    gut symbionts
  • Fungus: Hymenoptera (woodwasps),
    Coleoptera, Diptera, Lepidoptera – may
    specialise on different fungal stage
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12
Q

outline the ecosystem services provided by xylophagy

A
  • accelerate wood decomposition
  • saproxylic insects are often predators and reduce economically damaging pest pops
  • aquatic spp indicators of water quality and mediators of enegry flow and nutirent cycling
  • contirbut to wood webs as food for predators
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13
Q

outline what a coprophage is and give some examples of species

A

specialise in the consumption of faeces from large herbivores
e.g.
*Diptera – Scathophagidae, Muscidae,
Faniidae, Calliphoridae oviposit or
larviposit on dung
*Coleoptera – Scarabaeidae = dung
beetles disturb dung and limit fly
breeding
*Termites (Blattodea) - bring large
quantities of dung below soil surface

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14
Q

outline the different categories of dung beetle

A

Rollers = telecoprid
Tunellers = paracaprid
Dwellers = endocoprid

~60 UK species

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15
Q

outline the role of termites as coprophages

A

role in the removal of fung
= diverse group (126 spp) reproted to feed on wide range of mammalian dung
= ecosystem services include dung removal (pest and disease control), soil formation and nutrient cycling

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16
Q

outline what a necrophage is

A

species whcih eats carrion from another animal that it did not kill
= food source supports wider variety of insects
= form of succession of colonising spp as the decay progresses

17
Q

outline the ecosystem services provided by coprophagy

A
  • burying and consuming dung, protecting livestock from pests and disease
  • improvement of nutrient recyling and soil structure
  • seed dispersal

= provide ecosystem services valued to be around $380 million per year

18
Q

outline ecosystem services from necrophagy

A

improves soil structure
cycle nutrients from degrading plant and animal organic matter
supports decompositon of organic matter and stores directly in tissues
contirbutes to scientific culture services= foresnic entommology and maggot therapy

19
Q

what is forensic entomology

A

the application of insects to legal issues

20
Q

what are the five stages of decomposition

A

1) fresh stage
2) bloated stage
3) decay stage
4) dry stage
5) remains stage

21
Q

outline the fresh stage of decay

A
  • autolysis of cells and tissues by cellular enzymes
  • no outwards signs of physical change
  • anaerobic organisms begin to digest organ tissues
    = no odur
    = livor mortis, rigor mortis and algor mortis
22
Q

outline the species of insect which are associated with the fresh stage of decomposition

A

a) Calliphoridae (blow flies) arrive first – often within
minutes of death/exposure
* Calliphora vomitoria or C. vicina
b) Deposit eggs within 1-3 hours
c) Adult flies of families Sarcophagidae (flesh flies)
and Muscidae also common in first stage of
decomposition
d) Adult ants may be present and will feed on carcass
and eggs/larvae of flies
Fly activity peaks 48-72 h after death

23
Q

outline the bloated stage of decomposition (2-6 days)

A

*Activity of anaerobic bacteria in abdomen
create gases (H2S, CO2 and methane)
*Accumulate and cause distension of abdomen
* Gases produced also cause natural liquids
and liquefying tissues to become frothy
* Gases also force fluid out body and may
cause rupture
* Odour of putrefaction noticeable
* Colour change and marbling of skin observed

24
Q

what species of insect are associated with the bloated stage of death

A

Calliphoridae remain present in great numbers
*Calliphoridae (blowflies), Sarcophagidae (flesh
flies) and Muscidae continue to lay eggs
*Piophilidae (cheese flies) and Fanniidae arrive
*Ants continue to feed on eggs and larvae of flies
*First species of Coleoptera arrive -
Staphylinidae (rove beetles), and Cleridae
*Feed on fly eggs and larvae
*Affect the interpretation of range of insects and
insect life stages present as they feed

25
Q

outline the decay stage of decomposition (5-11 days)

A

*Beginning of active decay stage marked by
deflation of carcass
* Feeding dipteran larvae pierce skin and internal
gases are released
* Carcass has characteristic wet appearance due
to liquefaction of tissue
* Flesh from head and around anus and umbilical
cord is removed by larval feeding activity
*Strong odour of putrefaction associated with
carcass

26
Q

outline the insect species associated with the decay stage of decomposition

A
  • Feeding larvae of Calliphoridae dominant insect group
    *Early stages - larvae concentrated in natural orifices;
    later stages - larvae concentrated in thoracic and
    abdominal cavities
  • Numbers of adult Calliphoridae and Muscidae
    decrease
  • First members of Sepsidae arrive at carcass
  • Coleoptera become dominant adult insects - numbers
    of Staphylinidae, Silphidae (carrion beetles, e.g.
    Nicrophorus humator) and Histeridae (e.g. Hister
    cadaverinus) increase
27
Q

outline teh advances stage of decomposition

A
  • Most of flesh removed; some may remain in
    abdominal cavity
    *Strong odours of decomposition fade
  • Decomposition inhibited due to loss of
    cadaveric material; insect activity also
    reduced
    *If carcass located on soil, surrounding area
    shows evidence of vegetation death
  • CDI surrounding carcass will display increase in soil carbon and
    nutrients (e.g. P, K, Ca, and Mg; changes in pH; significant increase in
    soil nitrogen)
28
Q

what species are associated with the advances stages of decomposition

A

This stage marks first mass migration of third
instar Calliphoridae larvae from carcass
*Piophilidae (cheese fly) larvae may also be
present
* Few adult calliphoridae are attracted to
carcasses in advanced decay
*Adult Dermestidae (skin beetles) arrive at
the carcass
*Adult dermestid beetles may be common,
whereas larval stages are not

29
Q

outline the remain stage of decomposition

A
  • Greatest number of species reported to occur in late
    decay and dry stages
  • Dry decay stage characterised by movement from
    previously dominant carrion fauna to new species
    *Very few adult Calliphoridae attracted
    *Adult Piophilidae (cheese flies) emerge
  • Dermestid beetles, common in advanced decay,
    leave carcass
  • Non-carrion invertebrates commonly arriving are centipedes,
    millipedes, isopods, snails and cockroaches
30
Q
A

Entomology (16 decks)

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