Leaf‐feeding Resistance to Bollworm and Tobacco Budworm in Three Soybean Plant Introductions¹

Three plant introductions (PI 171451, PI 227687, and PI 229358) of soybean [ Glycine max (L.) Merr.] having resistance to the Mexican bean beetle [ Epilachna variveslis Mulsant] were evaluated in the laboratory for leaffeeding resistance (antibiosis) to the bollworm [ Heliothis zea (Boddie)] and tobacco budworm [ H. virescens (Fabricius)]. Five commercial cultivars were used for comparison. Criteria for antibiosis were larval mortality, larval and pupal weights, and duration of larval stage. All three plant introductions were resistant to both species. Among larvae fed on the plant introductions, mortality was greater than among larvae fed on the commercial cultivars, weight gains of larvae were reduced and time to pupation was greater. On the basis of percentage of larval mortality, PI 171451 and PI 229358 were more resistant to the bollworm than to the tobacco budworm; PI 227687 was equally resistant to both species. None of the larvae of either species survived on PI 227687, which suggests that this plant introduction may have a different genetic basis for resistance.