Stem borer herbivory dependent on interactions of sugarcane variety, associated traits, and presence of prior borer damage

Abstract

BACKGROUNDHerbivory risk is mediated by plant traits related to nutrition and defense that can vary within a species by genotype and age. Prior herbivore damage accrued by a plant can also interact with these traits to alter future herbivory potential by changing plant quantity or quality. Sugarcane (Saccharum spp.) is a perennial crop where above‐ground biomass is harvested annually and with varieties differing in nutrition and defenses, making it conducive to evaluating varietal resistance mechanisms. Using data from 16 sugarcane varieties and 28 years, we assessed damage from the primary pest in Louisiana, the sugarcane borer (Diatraea saccharalis, SCB), relative to variety, crop year (ratoon), plant traits, and incidence of prior herbivory.RESULTSSCB damage differed among varieties but not crop year, mostly following previously established classifications of SCB resistance, and correlated with select nutritional and defense traits. Within a crop year, the probability of SCB damage increased with prior conspecific damage on the same stalk. However, the strength of this prior damage effect did not match known resistance patterns but still differed with variety.CONCLUSIONSInteractions of plant variety, traits, and prior pest damage but not age impacted sugarcane borer risk. Borer damage was associated with nutritional traits of fiber and sugar content but not consistently with defensive traits like high stalk wax or hair density, indicating there may be additional resistance traits or indirect impacts of these traits on predators.This article is protected by copyright. All rights reserved.

Sugarcane borers: species, distribution, damage and management options

“…Resistance to borers in sugarcane manifests in leaves or stems, impeding or retarding larval ingress into the stalks (Kvedaras et al 2007). Traits linked to leave, such as narrow leaves, leaf shedding, erect leaves, long leaf spindles, low leaf senescence, and those related to stems, including high fiber content, light stalk color, heavy wax coating, thin stalks, high vigor, high juice content, and rind hardness and epicuticular wax composition, have served as criteria for ranking entries based on their resistance to borers (Long and Hensley 1972;Ngwuta 2015;Reagan and Mulcahy 2019;de Mello et al 2020;Wartha et al 2022;Penn and Read 2023). The selection of numerous resistant sugarcane cultivars has been facilitated by these pivotal resistance traits.…”