Biological Controls
Marijuana Horticulture
by Jorge Cervantes
Predator and parasite availability and supply have changed substantially over the last 10 years. Today, many more predators and parasites are available to home growers than ever before. Shipping, care, cost, and application of each predator or parasite is very specific and should be provided in detail by the supplier.
By definition, a predator must eat more than one victim before adulthood. Predators, such as ladybugs and praying mantises, have chewing mouth parts. Other predators, such as lacewing larvae, have piercing-sucking mouth parts. Chewing predators eat their pray whole. The piercing-sucking type, suck the fluids from their prey’s body.
Parasites consume a single individual host before adulthood. Adult parasitoids typically place a singe egg into many hosts. The egg hatches into larvae that eat the host insect from the inside out. They save the vital organs for dessert! Most often, the larvae pupate inside the host’s body and emerge as adults.
Parasites, unlike predators, hunt until the prey is almost eliminated. Predators chose to be surrounded by prey. When prey population starts to diminish a little, predators move on to find a nice, fat infestation. They never truly eradicate the pests. This is why predators work best for preventative control, but are slow to stop an infestation.
The rate at which the predators and parasites keep the infestation in check is directly proportionate to the amount of predators. The more predators and parasites, the sooner they will get infestations into check. Predators and parasites outbreed their victims, reproducing faster than pests are able to keep up with.
When predators and parasites are introduced into a garden, special precautions must be taken to ensure their well-being. Stop spraying all toxic chemicals at least two weeks before introducing the predators. Pyrethrum and insecticidal soaps can be applied up to a few days before, providing any residue is washed off with fresh water. Do not spray after releasing predators and parasites.
Predators and parasites survive best in gardens that are not sterilized between crops. Gardens with perpetual harvests are ideal for predators.
Most of the predators and parasites that do well in an indoor HID garden cannot fly. Insects that can fly often head straight for the lamp. Ladybugs are the best example. If 500 ladybugs are released n Monday, by Friday, only a few die-hards will be left. The rest will have popped off the lamp. If using flying predators or parasitoids, release when it is dark. They will live longer.
Predators are most often very small and must be introduced to each plant separately. Introducing predators to a garden and plants takes a little time and patience. Predators also have very specific climatic requirements. Pay attention to the predators’ needs and maintain them for best results.