Use of sugar beet foliage by the introduced leafmining fly Amauromyza flavifrons (Diptera: Agromyzidae)

Abstract

Laboratory and field experiments investigated the use of a nontraditional host, Beta vulgaris L. (sugar beet), by the leafminer Amauromyza flavifrons Meigen. In laboratory trials using leafminers from the northeastern United States where sugar beets are not grown commercially, female flies readily oviposited on B. vulgaris even when a commonly used host, Saponaria officinalis L., was present. However, larval mortality was significantly higher on B. vulgaris than on S. officinalis and occurred at an earlier instar. Larval mortality on S. officinalis was significantly correlated with the number of miners in each leaf, suggesting an effect of larval competition, whereas on B. vulgaris, larval mortality was independent of the number of miners in a leaf. Results from an experimental garden array in the northeastern United States showed that wild, unconfined A. flavifrons females will oviposit on B. vulgaris and confirmed substantial early larval mortality on this plant. Implications of female oviposition and larval mortality on B. vulgaris are discussed in terms of the probable spread of this fly to western sugar beet growing regions.