WHAT IS BIOLOGICAL CONTROL
A major weapon in the arsenal of integrated pest management is biological controls, which is defined as a reduction in pest populations by natural enemies (Cornell University). You may have heard of putting lady bugs or praying mantis in your garden to help eradicate unwanted garden pests before. While those are certainly popular for a reason, there are a whole slew of other control agents including predators, parasitoids, and pathogens which can help control garden pests. These good bugs are often a fast solution to eradicate the bad bugs because it typically only takes a minimal initial purchase and very little time or management after that. I am going to briefly discuss each type of control and how it can be used to your advantage in your own home garden.
TYPES OF BIOLOGICAL CONTROLS
Predators are the most common form of biological control. These include lady bugs, praying mantis, green lacewing, and aphid lions. These predators either eat the entire pests body OR will suck the fluids out of it thus killing it. They tend to be an immediate fix for a problem but in general are not preventative since they will need to leave the area to find more food once a source is depleted. In most cases predators will eat whatever they are able to – for example green lacewings will eat all small soft bodies creatures such as aphids, mites and thrips that they come across which means they can help control more than one type of pest.
Parasitoids, which include many species of wasps and some flies, provide a preventative aspect since the adults will lay their eggs inside the host which will eventually destroy the host from the inside out. This will create a scenario where the agent may be absent but its effects are still being felt. Unfortunately parasitoids tend to be highly specialized to one species or type of insect so you wont have a blanket effect like with the predators. Still they are a highly effective means of biological control.
Pathogens are disease causing agents such as bacteria, fungi, viruses, and nematodes that can be introduced into your soil and plants with a long lasting effect. They will kill or debilitate their host and readily transfer from host to host if it is brought back to a colony. These agents are great because they will remain in the soil until there is another resurgence in the pest population and are not harmful to humans or other biological controls since they are highly specialized to their hosts. Thus they make an ideal compliment to predators and parasitoids.
HOW TO GET BIOLOGICAL CONTROLS
There are two approaches to bringing biological controls into your garden – conservation and augmentation. Conservation is where you manage your garden to allow natural occurrences of agents to flourish by creating habitat for all life stages of the insect and eliminating pesticide use. This is the more cost effective way but does take more time to get populations to thrive. Augmentation creates an immediate effect because you purchase the biological control in larger quantities and release them directly into the garden. You can purchase a plethora of biological controls online and have them shipped to your home with release instructions. Both are effective means of integrated pest management and can be a great addition to your sustainable garden.
A few things to note:
- If you do not provide food sources for ALL life stages of the biological control then you will not have a self sustaining population.
- You can not use broad scale pesticides (organic or otherwise) while these insects are at work for you since pesticides kill indiscriminately.
- Take care when killing pests by other means that you don’t accidentally misidentify and kill another life stage of your control agent since eggs, pupae, larvae, and adults can look completely different at each stage.
- Some controls will kill your other agents (for example praying mantis will eat ladybugs if given the opportunity) so consider their predator prey interactions, strategically time your introductions, or simply accept that natural balance is in play here.