prey and predators depends in each other .in the absence of one another is useless or meaning less. predators is responsible for population of prey.if less predators more prey and more predators means less prey.
1:50 => 1 part oil + 50 parts high-octane gasoline STIHL Premium two-stroke engine oil comes in individual bottles of 100ml, 200ml, 500ml and 1000ml (1 L).