ACYLGLUCOSES FROM WILD TOMATOES ALTER BEHAVIOR AND REDUCE GROWTH AND SURVIVAL OF HELICOVERPA-ZEA AND SPODOPTERA-EXIGUA (LEPIDOPTERA, NOCTUIDAE)

2,3,4-Tri-O-acylated glucoses (acylglucoses), exuded by the trichomes of the wild tomato species Lycopersicon pennellii (Corr.) D'Arcy, are feeding or oviposition deterrents, or both, for a wide range of insect pests of cultivated tomatoes. We conducted this investigation to ascertain the effect of acylglucoses on Helicoverpa zea (Boddie) and Spodoptera exigua (Hubner), major pests of cultivated tomatoes. Findings indicated that the acyl glucoses reduce growth and development of larvae of both species. Exposure to the compounds, in artificial diet and applied with spray to cultivated tomato leaves, resulted in retarded growth rates, extended duration of the life cycle, and reduced survival. In behavioral bioassays, acylglucoses were observed to deter host selection and feeding by neonates and third instars of both insect species. S. exigua consistently exhibited greater sensitivity to the presence of the compounds than H. zea. A simulation of the cumulative effects of the compounds on population development of both species in a field of acylglucose-producing tomato plants projected a decrease in the number of generations per season and dramatic reductions in population size, relative to the control field of standard tomato varieties. Acylglucoses also were found to stimulate H. zea oviposition behavior, which may be attributed to activity of the fatty acid moieties of these molecules. The threshold level for response by moths to these compounds was below 50 mug/cm2. These compounds affect H. zea and S. exigua growth and survival at levels that reasonably might be attained in a breeding program to develop acylsugar-synthesizing tomato cultivars. Implications of these results for the deployment of acylsugar-producing plants and assessment of their potential pest resistance are discussed.