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|Jazyk:||Počet slov:||3 882|
|Referát vhodný pre:||Stredná odborná škola||Počet A4:||11.9|
|Priemerná známka:||2.98||Rýchle čítanie:||19m 50s|
|Pomalé čítanie:||29m 45s|
The leaf-cutting ant has a mutualistic relationship with the fungus, which they cultivate on fresh plant material. The species of fungus used is from the basidiomycte family called Lepiotaceae. Some researchers say that all gardening ants cultivate a single form of the fungus species, Leucocoprinus gongylophorus (Hoyt 1996). Leaves are brought in by workers and then reduced to a pulp and incorporated with their saliva and fed to the fungus. These fungi produce swollen hyphae (gongylidia), bunches of which are known as staphylae. These provide food for the ants and their larvae (Weber 1972). For the best productivity, the fungus garden must have a structure that combines a large area for the production of staphylae (the ant’s food) with the smallest chamber volume which can be maintained and with accessibility to the workers (Bass & Cherrett 1996). Most of the fungus garden can be only accessed by minima workers because the small passageways in the fungus limit the size of ant that can pass through. In the fungus garden there is more surface area on the inside than the outside and there is more fungus (staphylae) on the inside than the outside. Thus there is a much greater need for small ants in the fungus garden than large ants. Since the outer surface can be accessed by all ants, there is a much greater harvesting pressure on it than the interior surface of the fungus garden. The outside of the garden appears to be heterogeneous. Another important feature of the fungus garden is how long the substrate material will support the growth of the fungus. It is found that fungal gardens have a life cycle of 7 weeks to four months. The length of time the fungus can grow on the substrate is related to the season the type of substrate the ants use. The outside of the fungus garden is heterogeneous. The upper part is a green-gray color with large cells, and this is a young garden where most of the fresh substrate is added. Fungus gardens get older from the top down. The further down you go on the garden, the grayer it will look and the cells will become smaller because of the pressure from the fungus on top. Eventually the holes become so small that minima ants can not have access to the interior of the garden. Old gardens have thinner walls then new gardens. Since the walls become thinner and the holes become smaller the surface are per unite of volume becomes greater in older gardens. On an average, 74% of the total garden surface area is internal. The interior cells of a fungus garden have an average area of 2.17 mm square and a circumference of 5.71 mm square.