Ďaľšie referáty z kategórie
|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|
About 90% of the ants found in the interior of the fungus garden were minima. When the ants start to put down new substrate, the first staphylae is produced in about 4-5 days. The best production comes in about 20-30 days after substrate is added. Smaller cavities have more staphylae per unit are than larger ones. Therefore the older the garden becomes, the more food the ants get until about 7 weeks later when the fungus runs out of substrate. As you can begin to see, there is two antagonistic things working for and against the ants. The ants want to maximize production (keep cells small so more staphylae grow per unite of area and to maintain a high humidity) but also they want to keep the garden accessible for all workers (Bass and Cherrett 1996).
After reading the above paragraph you are left with some questions. Do the leaf-cutting ants have any mechanical action on the fungus to improve its productivity? Does the fungus garden need to me tended after substrate is given to the fungus? I will answer these questions using (Bass & Cherrett 1996). The presence of workers on the fungus stimulates staphylae production in a number of ways. Workers frequently defecate onto substrate that they have just added to the garden (Quinlan & Cherrett 1977). It turns out that the fungus lacks enzymes to degrade protein so it can’t receive any nitrogen compounds from the substrate. The ant feces contain ammonia and a mixture of amino acids (Boyd & Martin 1975) which supplies the need of the fungus. The ants also prune the fungus when they eat the staphylae. Studies have shown that about four days after pruning, the fungus grows more staphylae then if it hadn’t of been pruned. If a fungus garden is not pruned, then large white growths appear on the fungus surface. This coincides with low worker populations and a small number of staphylae. The ants eat staphylae when they are of medium size. Old staphylae are large. It is interesting that if the fungus is not pruned, staphylae is not produced. This show the implication that the leaf-cutting ant and the fungus have evolved in such a way that both can not live without the other. How does the fungus keep from being totally consumed by the ants? It turns out that most of the hyphae of the fungus is mixed up with the inedible fragments of vegetation. The hyphae becomes available to the ants only when it grows out of the vegetation to produce the edible staphylae (Bass & Cherrett 1996).