Richard Wall - Dung Flashcards
uses of dung
fuel for cooking in india - forms dried out ‘cakes’
Masai house roofed with dung, grass and mud.
Burkina Faso - buildings made from clay soil, straw and dung
how much dung is produced in the UK per day?
300,000,000kg per day
10m cattle each produce 25-30kg per day.
what communities live in dung?
Coprophage communities, with v complex food webs.
high water content, 70-90%
relatively high energy content
3 types of dung beetles and behaviour
- Endocoprid beetles
dig tunnels and lay eggs within brood chambers, in or just beneath the dung pat. - Paracoprid beetles
tunnel down and build brood chambers well below dung. roll balld of dung down into chambers and lay eggs inside ball. M+F work together to excavate chambers. some beetles rob existing tunnels, or build side tunnels to sneakily mate with other females. - Telocoprid beetles. roll fresh dung away to suitable dry sandy site, dig and drop ball underground. brood ball can be 50x weight of beetle., sexual display.
example of a specialist dung breeder fly
Yellow dung fly, Scatophaga stercoraria
very early in succession of dung.
adaptations for v wet environments eg respiratory horns/siphons
describe colonisation and succession of cow pat
flies first
beetles a few hours later
crust forms after a few weeks making colonisation difficult, broken up by insects.
earthworms last, bring bits underground.
the pat only gets colonised by half the species present in the pasture, as species are highly aggregated due to oviposition.
where are dung Insect communities more complex?
in temperate habitats the dung remains available longer.
May contain more than 1000 insect inhabitants from over 400 sp.
faeces from different hosts have a unique decomposer fauna. specialists due to chemical and physical properties of the dung
what is colonisation affected by?
Age of the pat Time of year Water content Surrounding habitat Weather Soil type Continuity of dung availability Position within a field Stochasticity Dung composition – grass, grain other forage FOLLOWING INITIAL COLONisAtiON - competition, predation and parasitism.
Why are insect dung-colonizers important?
- decomposition must occur, otherwise causes pasture fouling.
- dung insects provide food for other animals.
- N and C cycles: to maintain pasture fertility. measurable growth response by surrounding herbage, plus decrease in soil density and increase in porosity.
- reduced GH gas emissions.
monetary value of dung insects
£300million per year
£37 per cow
quantification of GH emissions based on quite flimsy data/
life cycle of cattle GI parasites
eg Haemonchus
eggs laid in dung, develop L1 to L2in dung then escape to pasture. L3 in pasture, infect grazing cattle.
describe an investigation which lead to conclusion that insect dung commuities, mainly small endocoprid Aphodius sp, can reduce availability of livestock gastrointestinal parasites on pastures
collected 400kg dung from organic farm, didnt contain deworming treatment.
- made 260 ‘pats’ in fields, 4 groups
mesh to exclude insect colonisation, natural, added beetles, enhanced rainfall.
- counted FEC and larval culture , identified L3.
- found 109 eggs per gram.
66% Cooperia oncophora, 29% Ostertagia ostertagi; 5% Cooperia spp.
- also sampled grass around pats by cutting it and putting in a muslin bag and tube with liquid at one end. causes larvae to migrate towards water, so can remove and count.
- no. larvae increases over 6 weeks then stays high.
concluded aeration of pats by beetles prevents unfavourable anaerobic conditions which promote L3 development. rainfall slightly enhanced this.
how is marsupial dung decomposed in australia?
- native dung beetles adapted to remove it
- imp as w/o it, build up of cattle dung on pasture and loss of grazing space.
- would have increase of dung breeding bush fly, musca vetustissima.
what came major problem after cattle introduced in Australia? how was this combated and was it successful?
dung breeding bush fly , musca vetustissima.
a very thorough quarantine, selective breeding programme to release more dung beetles. after 8 years released 20 species. However, did not spread, required repeated introduction to new areas. worked well on local scale.
describe exclusion experiment son dung beetles.
left dung covered for different amounts of days. worked out % weight loss of dung.
most dung loss in first two days - showing earlier colonisers most imp.
what is a ruminal bolus?
capsule sent down throat of cows and into digestive system. releases chemicals in pulses over time. eg Ivermectin (macrocyclic lactone)
describe an experiment looking at long term effect of ivermectin
Sommer et al 1992.
calves fitted with ruminal bolus delivering ivermectin at 40µg/kg
made pats of control and test dung.
at 38 days, saw crumbly appearence, due to colonising beetles breaking the surface.
94 days - ivermectin treated dung surface not broken.
control at 93 days almost completely decomposed.
suggests chemicals have long lasting effect, mainly on flies and beetles.
90% of dose is excreted, unchanged.
is a pour on or injection of ivermectin more damaging?
pour on reaches much higher concentration faster than injection. also remains detectable in dung for 2 weeks . intramuscular injection remains longer so ends up being more damaging
what was found from comparing dung treated with ivermectin, doramectin and control.
found control had highest number of fly larvae at each time period.
Ivermectin had more than doramectin.
most fly larvae 29 days after treatment.
also compared ch concs in faeces. after treatment, IVM conc declines.
post deposition, conc increases and remaining IVM is locked away in dung and stays there at toxic levels.
5 sub lethal effects of macrocyclic lactones persisting in dung.
Reduction in fecundity Increased larval development time Morphological abnormalities Disruption of water balance interference with moulting
fly repellant with very short effect
deltamethrin. short pulse ofactivity 2-3 days after treatment.
why is it often difficult to see the effects of insecticides in dung?
dung beetles roll it underground, toxic effects occur underground
experiment to measure effect of pyrethroid insecticide in botswana.
botswana - dosed dung and measured the number of dead dung beetles.
what is an alternative to conventional insecticides
dried planktonic diatoms
dessicates environment, causing damage to bed bug cuticle
as effective as ivermectin at reducing dung fauna.
what do longer term ecological effects of anthelmintic residues depend on?
Compound used,
Metabolism/storage/excretion route and rate
Dose rate,
Formulation and delivery method (pour on, injection, bolus)
Number and age-classes of treated animals
Frequency and seasonal time of use
Husbandry practices (stocking density, housing)
Weather
Nature of the dung insect community
