A Relative Resistance Ratio for Evaluation of Mexican Rice Borer (Lepidoptera: Crambidae) Susceptibility Among Sugarcane Cultivars

Abstract

The Mexican rice borer, Eoreuma loftini (Dyar), is a major pest of sugarcane (hybrids of Saccharum spp.) in Louisiana and Texas. Resistance to E. loftini was evaluated in 51 commercial and experimental cultivars of sugarcane, energycane (hybrids of Saccharum spp.), and sorghum [Sorghum bicolor (L.) Moench and hybrids of Sorghum spp.] in four replicated small plot field experiments from 2009 to 2012. A relative resistance ratio was developed to compare levels of susceptibility among cultivars based on the percentage of bored internodes and survival to adulthood. This index was able to separate cultivars into five resistance categories and provides a new method for comparing levels of resistance among cultivars. E. loftini pest pressure in 2009 was among the highest recorded with injury ranging from 55 to 88% bored internodes. Commercial sugarcane cultivar HoCP 85-845 was identified as resistant in three of four experiments, whereas HoCP 04-838 was identified as susceptible in all experiments. Of the five sugarcane cultivars in commercial production in the Rio Grande Valley of Texas, only TCP 87-3388 was categorized as resistant. Of the cultivars with potential for bioenergy production, all of the energycane cultivars demonstrated higher levels of resistance than high-biomass and sweet sorghum cultivars. Continued evaluation of cultivar resistance to E. loftini is important to development of effective integrated pest management strategies for this pest.

Assessing resistance of sugarcane varieties to sugarcane borer Diatraea saccharalis Fab. (Lepidoptera: Crambidae)

“…However, it is difficult to distinguish how much of this effect is caused by deterrence, low plant quality for the insect, or antibiosis (Dinardo-Miranda et al, 2012;Stout, 2013). The lack of correlation between tunnel length and larval development within the stalks indicates that once the larvae are established within the stalks, other resistance factors affect their development, as reported by Bessin et al (1990) and Wilson et al (2015).…”

Selected Abiotic and Biotic Environmental Stress Factors Affecting Two Economically Important Sugarcane Stalk Boring Pests in the United States

“…Various entomopathogens and entomogenous nematodes have been tried and they also failed under field conditions [14,34,39]. Planting resistant sugarcane cultivars is another way of protecting crop yields against pests, and some cultivars of sugarcane that offer degrees of resistance against E. loftini are becoming available and new resistance factors have been identified [14,53,63]. Although some cultural practices (e.g., plowing down sugarcane stubble in fallow fields and selecting optimal planting dates) have been suggested [14,53], they have not been implemented for E. loftini management.…”

“…The preference of E. loftini to oviposit on drought stressed sugarcane [14,53,[68][69][70] was demonstrated when a sugarcane cultivar resistant to E. loftini (L 03-371) under well-irrigated conditions was found to be susceptible under drought conditions (up to 88% bored internodes) [14,53,63,91]. Reay-Jones et al [68] reported that well-irrigated sugarcane was 44% less susceptible to E. loftini oviposition and injury to the crop was ≈60% lower than in water deficit stressed sugarcane of susceptible (e.g., LC 85-384) and resistant (e.g., HoCP 85-845) cultivars but oviposition preference and levels of injury to stalks relative to each cultivar did not change (i.e., HoCP 85-845 had 44% less injury than LCP 85-384 within each irrigation regime) [68,70].…”

Mexican Rice Borer Control Tactics in United States Sugarcane

“…Eoreuma loftini injures 20% of sugarcane internodes in South Texas, incidentally providing portals for red rot, Colletotrichum falcatum Went., which breaks down sugar [20,27,28]. Larval population densities do not usually exceed one larva per sugarcane stalk in South Texas [29] but 50%–80% bored internodes were reported on some cultivars in Texas [3,4,30]. Nineteen percent bored internode injury in Texas resulted in an estimated decline in sugar yield of ≈25% [31].…”