Modeling the areawide impact of sugarcane varieties and predation on sugarcane borer (Lepidoptera: Pyralidae) populations in Southern Louisiana

A simulation model was developed to increase understanding of how varietal resistance and predation may affect sugarcane borer, Diatraea saccharalis (F.), populations on an areawide basis. The model includes the processes of immature development, oviposition, host-dependent mortality, and mortality due to arthropod predation. Varietal parameters in the model were obtained from replicated small-plot evaluation trials. Percentages of bored internodes were used to compare survival of sugarcane borers from the egg stage until establishment in the stalk among sugarcane cultivars with and without predator suppression. A relative survival index was used to estimate survival among cultivars, from establishment in the stalk until pupation. Simulations showed that differences in moth emergence and total emergence would be greatest in the absence of adult exchange among varieties. These studies indicated that the impact of susceptible varieties on sugarcane borer populations might be mitigated if these varieties are dispersed among varieties with greater resistance. Varietal differences observed in small-plot varietal evaluations were substantially magnified during simulations when the amount of adult redistribution among varieties was reduced. Based on this research, data obtained from small-plot varietal resistance studies alone may not adequately address the potential impact that such varieties, when grown on larger acreages, might have on pest populations