Lecture 18- Australian invertebrates' diversity III Flashcards
What is the classification of termites?
- P: Arthropoda C: Insecta O: Isoptera (termites)
- Remember: very diverse, widespread & abundant, thus a very important group in Australia
Why are termites important in nutrient cycling?
- important in nutrient cycling because many species feed on dead plant material, converting dead grasses & wood into soil very quickly
- symbiotic relationship with protists allows them to exploit this very abundant but poor quality food source
- Termites enrich soils with nitrogen & phosphates
- carry their food back to the nest, thus soil immediately around the termite mound/nest is gradually enriched with N and P
- over time this is redistributed into surrounding soils
- important!
Where in particular are termites important for recycling nutrients?
- important role in nutrient cycling in northern Australia due to pronounced wet-dry seasons & low nutrient soils
- when dry season nothing grows
- This system can’t support large endothermic grazers with high energy needs
How much of carbon do termites recycled in tropical systems?
-20%
-Tropical savannas in Aust. can’t support high density of grazing
vertebrates:
- 24kg of cow/ha (1 cow/25ha) - 40 to 120kg termite/ha
What are the mastotermes?
- large species, worst pest termite across tropical Australia
- type of termite
- impressive in success
- can chew almost through everything
What can invertebrates also be and examples? (parasites)
wildlife parasites: health impacts, disease etc.
- e.g. rump-wear in Mountain Brushtail Possums: mites?
- sarcoptic mange in wombats: mites?
What is the life cycle of a tick like?
-ticks: external blood sucking parasites
1.Generalised life cycle
adult female: takes blood meal from host (c) & mates
2.Lays eggs
3.Eggs hatch into larvae, quest for host(a) feed & drop off.
4.Larvae develop into nymphs, quest for host(b), feed and drop off
5. Nymphs develop into adults, quest for host(c)
-Hosts a,b&c may be different species
What are the issues when attempting to investigate parasite life cycles in wildlife?
- Many parasites have several stages in life cycle
- Different life stages of parasites may have different hosts
- Often difficult to determine which adult species the larvae or nymphs belong to
-Laboratory studies
What was the project investigating ticks infesting koalas?
- Different species of ticks infest koalas from different populations in Victoria!!
- Raymond Island, Gippsland – koala tick – Haemaphysalis bancrofti
- Far east Gippsland – also Ixodes holocyclus, the paralysis tick
- Phillip Island – koala tick – Ixodes tasmani * French Island – koala tick – Ixodes hirsti
How did they investigate the ticks in koalas?
-French Island, Vic
* Catch koalas each month, (several years of data
needed to demonstrate true seasonal patterns)
* Examine whole body for ticks – Ixodes hirsti
* Impacts on koala hosts: - low tick loads: minimal - high tick loads: anaemia
What was the seasonal pattern of adult tick infestation on French Island koalas?
- higher during September to February
- this is when they occur
- seasonal occurrence
What is the life cycle of the tick Ixodes hirsti that infests koalas?
- Lays eggs on ground
- Eggs hatch into larvae, and quest for a host – (species unknown, small mammal ?? e.g. native rat??) - feed & drop off.
- Larvae develop into nymphs, quest for unknown species, feed and drop off
- Nymphs develop into adults, quest for koala hosts (koalas move along ground to change trees)
- adult female tick: blood meal from koala & mate
How can you understand the life history of the koala tick, Ixodes hirsti?
-reproductive output
-Surveying for different life stages in the field:
- adult ticks - examine koala host - larvae and nymphs –identify host
if possible, or sample for questing stage:
-1. Fully engorged adult female ticks, taken back to lab and maintained for egg laying
2. Each females laid a mean of 3250 eggs over a period of 40 days
3. Eggs took approx 60 days to hatch Females back to Lab
4. Eggs hatched into larvae, but would not attach to rats or birds to feed thus next stage = nymph still not confirmed as I. hirsti
5. Intermediate hosts in field remain unknown
Why are cockroaches important?
- Very important in nutrient cycling (many eat wood)
- Australia has many native cockroach species e.g. Australian rhinoceros cockroach, the largest species in the world, 8cm
- important for conservation
How is habitat loss and fragmentation dangerous for invertebrates?
- invertebrates are small so the scale is different, cannot cross even small distances if cannot fly
- Habitat fragments:
- Patches and linear remnants of varying size, connectivity & spacing
- Composition: remnants of original vegetation, species mix & age of vegetation variable
