Abstract
Larvae of Ctenicera destructor were fed nine synthetic diets for 6 months at 68 ± 2 °F and 75% relative humidity. Seven of the nine diets were based on a diet developed for larvae of Heliothis sp. It was modified by adding putrescine or spermidine, or both; hot-water or 70% ethanol extract of tea leaves; residue from hot-water extraction of tea leaves; or hot-water extract of germinating rye seed. Two chemically defined diets based on a previously reported amino acid analysis of this wireworm were also formulated: one contained hot-water extract of germinating rye seed.More larvae survived on a diet supplemented with putrescine and spermidine, on one supplemented with hot-water or with ethanol extract of tea leaves, and on the unsupplemented chemically defined diet than on the other diets. They more than doubled their weight on a diet supplemented with putrescine and spermidine. Growth factors for C. destructor present in tea-leaf extracts and residue probably differ from those for Adoxophyes orana. Inhibitory and growth-promoting factors for C. destructor are apparently present in hot-water extract of germinating rye seed. Putrescine or spermidine, or both, or some related metabolic product, may be necessary for growth and development of C. destructor. Frequency of molting was not always indicative of dietary efficiency.