Resistance to the Mexican rice borer (Lepidoptera: Crambidae) among Louisiana and Texas sugarcane cultivars

Abstract

A 2-yr study to evaluate Louisiana and Texas sugarcane, Saccharum spp., cultivars for resistance to the Mexican rice borer, Eoreuma loftini (Dyar) was conducted in two locations in Texas, chosen for having different infestation levels. Criteria for assessment of resistance included percentage of bored internodes and adult emergence holes, the latter used to determine the relative impact of each cultivar on the potential areawide buildup or reduction of adult E. loftini populations. A recently released cultivar, HoCP 85-845, seemed to lose a portion of its resistance under heavy E. loftini infestation pressure, suggesting its value only in moderate-to-low infestation conditions. Cultivar CP 70-321 was the most resistant. Results indicated that cultivar LCP 85-384 was significantly (P < 0.05) more susceptible than NCo 310, traditionally the most susceptible cultivar commercially produced in Texas. In 2001, LCP 85-384, which now represents 85% of the production area in Louisiana, had the greatest moth production per hectare (17,052 +/- 3,956) under the lower infestation pressure, significantly (P < 0.05) higher than HoCP 85-845 (3,038 +/- 2,353). In a portion of the test at the high-infestation location, high levels of sodium and magnesium salt stress (15-30-cm soil depth) were associated with higher E. loftini damage in all cultivars except HoCP 91-555 and CP 70-321.