Humans are not alone in suffering the ravages of aging. Cockroaches endure it, too.

Case Western Reserve University researchers reported in the "Journal of Experimental Biology" that as the roach's life wanes between 60-65 weeks after the onset of adulthood, the insect slows down, experiences stiff joints, has problems climbing and experiences decreased spontaneous fleeing response. Death comes shortly after the onset of these movement problems.

Angela Ridgel, a postdoctoral fellow at Case, was the lead author on the National Institute of Health-funded study that looked at walking, climbing and righting behavior in the roach species, Blaberus discoidalis.

According to Ridgel, roaches reach adulthood after several molts. But after 60 weeks into adulthood, she observed in lab studies that elderly roach movement was much different from their younger adult counterparts.

Ridgel found that old roaches develop a "tarus catch" where the joint between its paw section and leg joint in the front (prothoracic) leg hardens causing the leg to list
to almost 45 degrees. As the roach moves forward, the front leg catches on the middle (mesothoracic) leg, which causes the roach to trip and to struggle to regain its tripod-like stance and gait.

This catch increased from 35 percent in the 60-week adults to 95 percent for 65-week adult roaches.

Changes in the sticky pads that help roaches climb walls or inclined surfaces also underwent a change from a supple, grey pads to hardened brown ones that eventually broke off, according to Ridgel. Removing a layer of cuticle in the roach paws, she also noted that tracheal tubes and a tendon that help create movement also hardened and browned, causing the paw to bend at the odd angle.

Ridgel said this study stresses the importance of multi-level approaches to the study of age-related changes in behavior and the nervous system.

"If we looked at only one study, we would have a skewed view of movement in these adult roaches. You need to test animals in a whole bunch of locomotor situations to get an idea of the potential changes that occur," Ridgel said.

She wrote the paper, "Effects of Aging on Behavior and Leg Kinematics During Locomotion in Two Species of Cockroaches," with Roy Ritzmann, Case professor of biology, and Paul Schaefer, a former Case graduate student who studied Periplaneta americana and contributed information about the roach's central nervous system and escape behavior.

Return to the online edition of the 1-15-04 Campus News.