EFFICIENCY OF FOOD UTILIZATION BY HELIOTHIS ZEA (LEPIDOPTERA: NOCTUIDAE) FED ARTIFICIAL DIETS OR GREEN BEANS

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Abstract
Second-instar Heliothis zea (more than the 275th generation) larvae from a 16-year-old culture, were fed either green beans or artificial diet until they reached the pupal stage and then were compared to determine their relative fitness to the two diets. They proved at least as well adapted to beans as to artificial diet with regard to most parameters. Final larval weights were equal, as were pupal dry weights. Wet weights were higher in diet-fed than in bean-fed pupae. Dry food consumption was higher in diet-fed larvae than in bean-fed larvae, but the reverse was true of wet food consumption. Total food consumption by larvae was limited by food volume rather than weight or composition. The larval stage was shorter in diet-fed than in bean-fed larvae; and diet-fed larvae had better survival, higher body nitrogen, and body energy content. Oxygen consumption was lower in bean-fed than in diet-fed larvae. Efficiency of food utilization was higher for bean-fed than for diet-fed larvae both in terms of dry matter conversion and energy conversion. Nitrogen utilization efficiencies were the same for both diets.