Biological control, using bugs to fight against bugs

Not all insects are pests. From a gardener's perspective, some beneficial bugs are the good guys of the insect world -- and if you can't raise your own insect army, you can hire mercenaries to defend your turf. Many species are hired guns, available from mail-order suppliers or nurseries for combating short but fierce pest outbreaks on chemical-free properties. Employing bugs to fight other bugs isn't a new idea. Reports indicate predatory ants were used to police citrus groves in ancient China. They also were released into desert oases in the Middle East, where insect pests were damaging palm trees. Begin your biological insecticide campaign by walking around the yard looking for troublemakers. Study the undersides of leaves for clinging aphids. Examine plants for foraging whiteflies. You might see deposits of sugary saliva or signs of munching. Carry a magnifying glass, an insect field guide or some local Cooperative Extension information with you so you can identify the organisms. Then you'll be ready to shop for the particular predators known to attack them. If aphids are sucking the life from your roses, then bring on the ladybugs, adults or larvae, which will consume entire colonies. "Timing is important for when you bring on the beneficials," said Jim Dill, a University of Maine Extension pest management specialist. "This isn't a proactive kind of thing. If you buy a bag of ladybugs and there aren't any aphids around, the ladybugs won't stick around long. They'll go somewhere they can find prey." Although green lacewing larvae often are considered to be the most efficient of the insect predators, ladybugs appear to be the most popular with home gardeners. Certainly, they're the best known.

But ladybugs are a flighty species, quick to head to places unknown. Releasing them in such a way that they stick around to do their cleanup work requires planning. "Habitat is the key for ladybugs, along with time of day," Dill said in a telephone interview from Orono, Maine. "Cooler mornings and evenings are best. A good way to do it is to put the bag [full of ladybugs] low into the foliage, almost to the ground. Make a small opening in the bag so they can come out one at a time. Lots of times when you do this, they won't fly. They'll simply crawl up the plants and go right after the aphids." Other supplier suggestions include carefully pouring a mixture of soda pop and water over the newly arrived ladybugs, coating their wings and preventing them from flying for a short period of time. You also might try releasing them only on overcast days, which would mean cooler temperatures, or you could place them on plants protected beneath Quonset-shaped fabric row covers. Several suppliers feed and water their beetles before shipping, claiming that will make them less likely to roam. Plan on being around to take delivery of any live insects you order, or provide an address for someone who will. The insects will require care as soon as they arrive, particularly nematodes, which don't survive long above ground. If you don't intend to release them immediately, place them in a refrigerator until you can.

Ladybugs and certain other predator species can survive at least a few weeks of refrigeration, allowing you the opportunity to make several releases, Dill said. Ants, by the way, should be controlled as much as possible before any beneficial insects are set loose. Ants and aphids seem to have developed a symbiotic relationship. Other bio-control measures include handpicking the pests off trees and other plants or pruning the damaged areas and depositing the trimmings in a landfill. You also might use bio-pesticides, "sometimes called reduced-risk pesticides, which are safer for humans and have fewer off-target effects," a North Carolina State University fact sheet states. You'll need to build a suitable, poison-free environment if you want to reinforce hired bugs with resident insects. That requires food, water, cover and pollen- and nectar-rich flowers known to attract many of the adult beneficials, whose larvae are so deadly against the problem species. "People should not expect perfection with bio-controls," the University of Maine's Dill said. "Organic methods deliver a little less perfection [than using chemical insecticides], especially with edibles. There will be some blemishes. It's usually more labor intensive to use bio-controls rather than chemicals, too. But the plus side is you're not exposing yourself, your family, your pets or the environment to any unwanted chemicals." via Associated Press.

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