Asian corn borer damage is affected by rind penetration strength of corn stalks in a spatiotemporally dependent manner

Asian corn borer, Ostrinia furnacalis (Guenée), is an important insect pest of maize throughout most of Asia. The rind of a maize stalk is a key barrier against corn borer larvae boring into the plant. There is a need to better understand the relationship between stalk strength and O. furnacalis larval injury, particularly for elite maize genotypes. To determine whether stalk strength is involved in maize resistance to O. furnacalis larval injury, 39 maize lines were evaluated in 2012 and 2013. Rind penetration strength (RPS) was measured at tassel (VT) and milk (R3) stages as a possible stalk resistance trait for O. furnacalis. RPS of primary ear internode at VT and R3 accounted for 37 and 38% of the variance in O. furnacalis injury (measured as number of holes) for simulated (artificially infested) first and second generation O. furnacalis, respectively. Relationships between stalk RPS values and tunnel length were weak. Results suggest that harder stalks have enhanced resistance to stalk boring but not to pith feeding or tunneling of O. furnacalis larvae. The RPS measures could provide classical maize breeders an important tool for evaluating stalk strength and corn borer resistance in maize. The assessments should focus on the internodes primary ear or above/below primary ear during both VT stage for first generation and R3 stage for second generation O. furnacalis resistance.