Rhodanse activity in the southern armyworm, spodoptera eridania cramer (lepidoptera: noctuidae)

Rhodanese activity in Spodoptera eridania Cramer, the southern armyworm, was investigated. The sources of rhodanese included southern armyworm larval midgut, fatbody, and Malpighian tubule mitochondria and isolated midgut bacteria. Several types of experiments were conducted to investigate rhodanese activity in the southern armyworm, these included: activity measurements in all different developmental stages; distribution of activity in several different organs; inducibility of larval midgut activity by dietary cyanide, methionine, cysteine, and thiosulfate; activity in seven species of bacteria isolated from the midgut. The ability of the bacteria to grow in a cyanide containing medium was established. In addition, a small survey of rhodanese activity in several other species of insects showed its presence in all of these.

The results of these experiments show that the southern armyworm has abundant rhodanese activity in all major organs and throughout all life stages apparently without regard to changes in its endogenous physiological conditions or to external dietary factors. There is no apparent relationship between rhodanese activity levels and tolerance to cyanide in the southern armyworm or in any of the other insect species.