Biomass Production of the Corn Earworm, Heliothis zea (Boddie) (Lepidoptera: Noctuidae), After Repeating or Switching Three Larva Diets for Four Generations

Abstract

The effects of repeating or switching, generation by generation, all possible combinations of three larva diets for four generations on the biomass production (grams per female per day) of the corn earworm, Heliothis zea (Boddie), were investigated. The diets were whole-kernel sweet corn (C), green tomato fruits (T), and an alfalfa-meal-based artificial diet (A). Biomass production of the fourth generation was calculated by dividing the total biomass production (eggs per female × pupal weight × percentage survival) by the days required for that generation (duration of preoviposition, egg, larva, and pupa stages). Treatments were replicated 20 times throughout the study. The entire experiment was repeated once. Significant differences ( P < 0.05) in biomass production were found among diet regimes AAAA, CCCC, and TTTT. Many other diet regimes consisting of switched diets also exhibited significant differences. The number of times that A appeared in a diet regime was positively correlated ( P < 0.01) with biomass production, whereas the opposite occurred with T. No correlation between C and biomass production occurred ( P < 0.05). Finally, no significant differences occurred in biomass production related to the number of times the diet was switched, although the results suggested a reduced biomass production as the number of diet switches increased. The results also indicate that the positive influence of A in the diet, or the negative influence of T, would be exerted for three generations after its use in the diet regime.