ORGANIC FLEA ASSASSINS

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The Beneficial Nematode Gets Tough on Fleas

People throughout the ages have searched for practical, organic pest control. Ancient Egyptians covered slaves in donkey's milk to keep the fleas away. Fashionable folks of the 18th century wore tubes filled with blood round their necks to deter the pests. But more recent home remedies such as garlic and brewer's yeast have been know to do little more, often nurturing healthy and happy fleas instead of deterring them.

Human history marches on, and a kinder, more effective flea control method is here. And as is often the case with nature, the solution was right in the earth.

The beneficial nematode, alias "killer roundworm," may be nature's simplest answer yet to troublesome, blood sucking fleas that infest backyards, homes, and pets each year like clockwork.

The nematode, Steinernema carpocapsae, hunts down fleas in the pre-adult, pupae, and larval stages of their growth, which account for 95 percent of the flea population, even searching out the fleas that lie dormant in cocoons before reaching maturity. The killer roundworm enters the pest's body through any convenient opening, such as the spiracles, where air is taken in, and releases a bacteria that kills the flea within 48 hours.

When the host is dead, the nematode sheds its skin and begins to reproduce inside the corpse. The offspring hunt for new prey, destroying the remaining fleas in the wake of the nematode life cycle. If there are no host bugs to be found, the nematodes starve and biodegrade, leaving no harmful backyard bug alive to tell the story.

The killer nematodes have been perfected and raised by Biosys, a company that specializes in biological pest control. At Biosys headquarters in Palo Alto, California, studies have been conducted over the past decade on the uses of the nematode.

The killer roundworm has been implemented commercially over the past five years to combat cranberry and citrus pests, but was never available to the garden growing public due to certain impracticalities in growing and shipping the "flea-killing commandos," say the nematode researchers.

Preparation of the nematode for widespread use had its difficulties, according to Doug Ross, an entomologist who has studied the worm developed by Biosys. In the past, nematodes were raised inside insects and then removed from the host's body to be used in pest control, which proved to be a costly and time consuming process. Then there was the problem of keeping the worms alive for storage and later use.

To solve these problems, Biosys designed a specialized fermenter to replicate perfect growing conditions.