Inside Job

The nematode family is as enormous as it is diverse.  The phylum holds an estimated 500,000 species, ranging in size from one micron to 26 feet in length.  But what is currently of interest to scientists is the worms' application in pest control. 

 "We study these nematodes - which are actually insect killers - not only to understand how diverse they are, but also to use them as biological control alternatives," Patricia Stock, a nematomologist at the University of Arizona, said last week.  "Using native biological control alternatives is more environmentally friendly than importing other pest control agents."

The juvenile phase of these tiny worms lives with bacteria in its intestines that kill specific insect species.  The nematode, hiding in the soil or in the bark of trees, waits for unsuspecting insects to walk by so it can either penetrate the insect either passively through a natural body opening, or aggressively using a sharp dorsal tooth.

Once inside the insect, the nematode vomits the bacteria, which kill the host from the inside out within 24 to 48 hours.  The bacteria digest some of the tissues, creating the perfect environment in which the nematode can grow and reproduce. 

One decaying insect provides a home suitable for one entire adult generation.  The juvenile, which is the only life-phase of the worm that can survive outside the dead insect, leaves home in a giant pack of 150,000 or more, each searching for a new insect host. 

-- Bjorn Carey

Image credit: Patricia Stock