Prior sugarcane borer damage does not impact conspecific damage or perennial crop yield in subsequent years of growth

Prior damage can alter a plant's susceptibility to future herbivory and yield potential, which is mediated, in part, by the plant's ability to regrow and changes in nutritional content. In perennial sugarcane (Saccharum spp.), herbivory by lepidopteran stem borers early in a growing season can increase the probability of conspecific herbivory later in the crop year. However, it is unknown whether the effects of prior borer damage either to vegetatively propagated seed cane or to standing plants can impact conspecific herbivory or crop yield in subsequent crop years. Using a long-term dataset and two field studies, we investigated the impacts of prior sugarcane borer (SCB; Diatraea saccharalis [F.]; Lepidoptera: Crambidae) damage on levels of conspecific damage across crop years. We also evaluated long-term impacts of SCB damage on plant quantity and quality, aspects that may alter future herbivory and yield. We found that prior SCB damage to either seed cane or standing crops did not alter conspecific damage in subsequent crop years. This prior SCB damage also did not impact plant quality (fiber, sucrose, and carbon content). However, foliar nitrogen was lower in plots without SCB damage in the first year but damaged in the second crop year. Metrics of plant quantity (tiller emergence and aboveground biomass) and total sugar yield were not impacted by prior years' SCB damage. Taken together, our data indicate that although SCB herbivory can significantly increase conspecific herbivory and impact sugarcane plants within a crop year, these effects were not sustained post-harvest following regrowth of aboveground biomass.