Probably the most common example of a plant pathogen in Colorado is the mildew that commonly covers squash plants in the late summer and early fall. A predator is an animal that kills another. One of the gardener's best friends is the Lady Bird Beetle. These beetles love to eat aphids and other small insects and mites, which left unchecked may kill your plants. The more Lady Bird Beetles you have, the less likely you will be to have aphid problems.
Mutualism is a relationship between two organisms providing benefits to both.
A honey bee's source of food is the nectar and pollen she will collect from your flowers. In return, your flowers are pollinated, and are able to set seed. The term symbiosis means living together. These bacteria supply nitrogen to the host, and the host supply food sources such as sugars to the bacteria. The physical environment of your garden includes light from the sun, heat, moisture, oxygen, wind, nutrients in the soil, and so forth.