Nutritional Ecology of the Southern Green Stink Bug Nezara viridula (Hemiptera: Pentatomidae) on Selected Varieties of Cowpea and Tomato

摘要

Cowpea, Vigna unguiculata (L.) Walp. (Fabales: Fabaceae), and tomato, Solanum lycopersicum L. (Solanales: Solanaceae), are two economically important crops in the southern United States. The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae) is a highly polyphagous pest that attacks a wide range of crops including cowpea and tomato causing a reduction in yield and produce quality. Considering the damage and the associated losses in cowpea and tomato production by this and other pests, as well as the demand for reduced use of pesticides, there is a need to cultivate varieties that are resistant to N. viridula. One key indicator of resistance is host nutritional availability and adequacy. This study evaluated the effect of two selected varieties of cowpea and tomato on the growth and development of N. viridula under laboratory conditions as a first step towards the assessment of nutritional adequacy of both crops. We carried out feeding experiments to compare food utilization and suitability by various life stages of N. viridula. The food substrates tested included fresh immature cowpea pods, fresh cowpea seeds, dry cowpea seeds and newly ripened tomato fruits. Overall, mean nymphal mortality was less when reared on cowpea (63.7±2.9%) than tomato (83.0±1.8%). Nymphs required less time to complete development on cowpea (27.8±2.8d) than on tomato (45.0±3.9d). Fresh body weight at adult emergence was greater on cowpea (132.3±12.1mg) than tomato (83.9±1.5mg). Consumption index (CI) and growth rate (GR) were higher on cowpea (CI: 22.0 ±1.3; GR: 2.1±0.3) than tomato (CI: 8.7±1.4; GR: 0.9±0.1). Collectively, these results suggest that cowpea provided a more suitable nutritional substrate for nymphal development. Many small vegetable growers cultivate both crops.