Identification of Multiple Insect Resistant Soybean Lines¹

Abstract

Five soybean [ Glycine max (L) Merr.] breeding lines derived from crosses involving P.I. 229358, a plant introduction with multiple insect resistance, were evaluated in a greenhouse or laboratory for leaf‐feeding resistance to the soybean looper (SBL) [ Pseudoplusia includens Walker], bollworm (BW) ( Heliothis zea Boddie), Mexican bean bettle (MBB) ( Epilachna varivestis Mulsant), and tobacco budworm (TBW) ( H. virescens Fabricius). The objective of the study was to determine if direct selection for resistance to one or two insect species would result in indirect selection for resistance to other species. P.I. 229358 (resistant parent), ‘Bragg’ (susceptible parent), and ‘Davis’ (highly susceptible check) were used for comparisons. All five breeding fines were as resistant as P.I. 229358 to SBL and BW larvae. Three of the five lines were also as resistant as P.I. 229358 to MBB larvae, based on percentage defoliation and pupal weights. On the basis of larval weights, duration of larval stage, and mortality, three lines were similar to P.I. 229358 in resistance to TBW larvae. Two of the breeding lines were similar to P.I. 229358 in resistance to all four insect species. Because some lines resistant to one, two, or three of the species may not be resistant to other species, identification of breeding lines with multiple insect resistance equal to that in P.I. 229358 should be based on evaluation against each species. These breeding fines could serve as basic germplasm for development of cultivars with multiple insect resistance and would be useful in evaluating the impact of resistance in an overall soybean insect management program.