Leaf-feeding resistance to six Australian noctuids in soybean

Abstract

The plant introductions (PIs) 171451, 227687 and 229358, the line Q15723, and breeding lines derived from Bragg × PI229358 and Davis × PI227687 crosses were bioassayed for leaf antibiosis resistance to the larvae of six Australian soybean-feeding Noctuidae species (Helicoverpa armigera, H. punctigera, Chrysodeixis argentifera, Diachrysia orichalcea, Nodaria externalis and Pantydia sparsa). Antibiosis resistance to all species was recorded. Lines consistently displaying the highest level of resistance were PI229358, PI171451, Q15723 and the breeding line ED73-112. PI227687 performed poorly against H. armigera, H. punctigera and C. argentifera and appears unsuitable for use in Australian insect resistance breeding programmes. Resistance was observed as some or all of the following: reduced larval growth rate, prolonged larval development, increased larval mortality, increased number of larval instars, reduced final instar larval weight, reduced pupal weight. Significant negative correlations between larval mortality and growth rate were recorded for H. punctigera and C. argentifera. Data for H. armigera, H. puntigera and C. argentifera indicate that final-instar larval weight can be used to quantify antibiosis resistance in soybean.