Host plant tomentosity affects arthropod pest and parasitoid efficacy

Abstract

Bemisia tabaci (Gennadius) is an important pest of many crops, and management practices vary from exclusively chemical to physical and biological. This study was conducted to determine the effective release rate of the parasitoid Eretmocerus mundus Mercet on B. tabaci infesting fresh market basil (Ocimum basilicum L.) and sage (Salvia officinalis L.) grown in walk-in tunnels. Sticky traps showed naturally occurring high whitefly densities in sage but not in basil. Eretmocerus mundus pupae were obtained from a commercial insectary and released at total rates of 10, 20, and 30/m² in sage and basil tunnels. In sage, no E. mundus parasitized nymphs were found; in contrast, E. mundus parasitization rate was about 6-33% in basil. There was a natural invasion of Encarsia lutea Masi, and parasitism in sage ranged from about 2-7% and 17-86% on basil. These unexpected field results led to laboratory trials on detached leaves and potted plants and confirmed the findings of tunnel-grown sage—there was no whitefly parasitism on sage by E. mundus. Whiteflies on sage were physically more rotund and did not flatten on leaf surface due to the densely pubescent leaves. The effects of different plant crops on whitefly parasitization are discussed.

Keywords:

• Sage
• basil
• Bemisia tabaci
• Eretmocerus mundus
• Encarsia lutea