PESTS and PARASITES A pest is an organism

PESTS and PARASITES -A pest is an organism that causes nuisance, -A parasite however is an organism (the parasite) that lives within or on another organism (the host) and does not contribute to the relationship (parasitism) but causes its host to suffer

Microorganisms • Some microorganisms are considered pests and some are indeed parasites. • The growth of microorganisms is dependent on many factors including: 1. The amount of Light 2. Temperature 3. Moisture level 4. p. H. Eg. Growth of Fungus on bread.

Food preservation Recall that one way for microorganisms to enter the human body is via the mouth. If food contain harmful microorganisms people can become very ill. To prevent food from providing a suitable environment for microorganisms to grow it may be preserved by the following methods:

• Salting - adding salt to the food (meat in most cases) causes it to become dehydrated (lose water content-less moisture) • Drying – another method to remove the moisture from the food • Pickling – the food is put in a brine solution (salt and water) and anaerobic fermentation occurs. The process produces lactic acid and allows an acidic p. H • Heating – kills most microorganisms depending on • Refrigeration – some microorganisms require warmer temperatures to have growth. The cold temperatures inhibits this growth • Adding sugar – the sugar causes it to become dehydrated (lose water content by osmosis-less moisture) discouraging growth of the microorganisms.

Proper waste disposal • When food and other waste are not disposed of properly it can encourage not just the growth of microorganisms but also the attraction of pests. • Some pests are cockroaches, flies, rats. • These pests carry microorganisms that cause diseases such as gastroenteritis, leptospirosis and meningitis for example. • These diseases can lead to death if not treated immediately

Responsibility • It is the responsibility of the individual, the community and the government to ensure that waste is disposed properly. • Some companies use their waste to recycle and create energy for their use. • This minimizes the amount of waste that has to decompose over a period of time. • Some examples are: 1. SC Johnson company uses nuts and other organic shells to power their plant 2. Companies using algae to convert carbon dioxide to oxygen. The carbon dioxide is obtained during combustion of fuels