Cross‐resistance between the Mexican Rice Borer and the Sugarcane Borer (Lepidoptera: Crambidae): A Case Study Using Sugarcane Breeding Populations

Abstract

The sugarcane borer (SCB) [Diatraea saccharalis (F.)] and Mexican rice borer (MRB) [Eoreuma loftini (Dyar)] are two economically important pests of sugarcane (Saccharum spp. hybrids) in the United States. Because of similarities in larval feeding behavior, selecting for resistance to one species could provide resistance to the other, a phenomenon we have termed “cross‐resistance”. The objective of this study was to determine if SCB‐resistance in sugarcane is correlated with resistance to MRB. Thirty genotypes from Louisiana previously identified as either resistant or susceptible to the SCB and 50 from Texas with unknown resistance status to either species were evaluated for percent borer‐damaged internodes. Data from the SCB‐resistant and‐susceptible genotypes were used to determine the SCB‐resistance status of all 80 genotypes. Similar (P = 0.578) levels of MRB damage were found between the Louisiana and Texas population, whereas, the Louisiana population suffered significantly (P < 0.05) less SCB damage compared to the Texas population. The SCB‐resistant genotypes suffered significantly (P < 0.01) less damage from the MRB compared to their susceptible counterparts. A significant (P < 0.001) association was found in percent SCB‐ and MRB‐damaged internodes among the Louisiana and the SCB‐resistant populations but not among the Texas or SCB‐susceptible populations. Furthermore, the SCB‐resistant genotypes were 40% less likely than susceptible ones to be bored by the MRB. Resources developed for SCB‐resistance could form the foundation material to breed for resistance to both pests.