The most important advantage to the use of biological control is that it typically offers longer term management than the more traditional technology areas. longer term control is achieved because biocontrol agents act as if a host specific control method is continualy present and impacting the target plant.
For example, once an agent is released and well established, insect population levels cycle proportionately with the population of the plant. that is when plant population levels are high, there will be a corresponding increase in the population levels of the biocontrol gents. when plant levels decrease, there is a corresponding decrease in the numbers of the biocontrol agents persist and continually exert controlling or regulatory pressure on the target plant. Disadvantages
Biological control can be fickle. Ultimately, you can’t control whatever natural enemy you set loose in an ecosystem. While it’s supposed to manage one pest, there is always the possibility that your predator will switch to a different target – they might decide eating your crops instead of the insects infesting them is a better plan! Not only that, but in introducing a new species to an environment, there runs the risk of disrupting the natural food chain. It’s a slow process.
It takes a lot of time and patience for the biological agents to work their magic on a pest population, whereas other methods like pesticides work provide immediate results. The upside to this is the long-term effect biological control provides. If you’re looking to completely wipe out a pest, biological control is not the right choice. Predators can only survive if there is something to eat, so destroying their food population would risk their own safety. Therefore, they can only reduce the number of harmful pests.