Effects of cytoplasmic polyhedrosis virus and bacterial contamination on growth and development of the corn earworm, Helicoverpa zea (Lepidoptera: Noctuidae)

Abstract

Bacterial contaminants, singly and in combination with cytoplasmic polyhedrosis virus (CPV), significantly influenced the growth and development of corn earworm, Helicoverpa (= Heliothis) zea. Among the four bacteria species studied, the most virulent was Pseudomonas maltophilia, followed by Bacillus subtilis, Escherichia coli, and Staphylococcus epidermidis. P. maltophilia caused severe losses in all stages of H. zea, with the larval stage being the most susceptible which led to more than a 60% loss in adult emergence. B. subtilis was the most virulent in the pupal stage and caused a 40% loss in adult emergence. E. coli did not significantly affect the survival of H. zea, but pupae and adults from contaminated larvae were smaller than those in the control. In all bacteria except S. epidermidis, the resulting H. zea adults were 25 to 114 mg smaller than the noncontaminated ones. The CPV did not affect survival of H. zea, but infected larvae and adults were smaller than those in the control. When combined with bacteria, CPV acted synergistically in some cases to further adversely affect growth and development of H. zea