Bedbugs were nearly eradicated with insecticides in the early 1960s, but their numbers are increasing now. Modern bedbugs have a thicker, waxy exoskeleton and resistance to common insecticides. How did these changes MOST likely happen in bedbugs

Spondylosis is the degeneration of the invertebral discs causing pain to the spine,
Disc slips are the rupturing of the tissue that separates the vertebral bones of the spinal column,
Sciatia is the compression of a spinal nerve root in the lower back, often owing to degeneration of an invertebral disc, afflicting pain to the back, hip and outer sides of the leg,
Hope this helps ;) .