Biology and cultural control of lesser cornstalk borer on sugarcane

Lesser cornstalk borer, Elasmopalpus lignosellus Zeller (Lepidoptera: Pyralidae), is an important sugarcane pest in southern Florida. It feeds on meristematic tissues of young sugarcane shoots and causes dead hearts, symmetrical rows of holes in the leaves, and plant death. Development and survivorship of immature stages, and reproductive, generation and population life table parameters of E. lignosellus were studied on sugarcane at nine constant temperatures. Development times were shortest between 27 and 30 °C. Lesser cornstalk borer required 543.5 degree days to complete development ranging from 22.8 +/- 0.3 d at 33 °C to 120.7 +/- 2.8 d at 13 °C. Pre- and post-oviposition periods decreased and oviposition period increased with increasing temperatures from 13 °C to 33 °C. Mean fecundity, stage-specific survival (lx), stagespecific fecundity (mx), intrinsic rate of increase (r), and net reproductive rate were greatest at 30 °C. The relationships between developmental rate and temperature, and between temperature and r, were best fit by the Briere-1 and -2 models, respectively.;A 2-year greenhouse experiment was conducted to document variety and age specific E. lignosellus feeding damage and yield effects in sugarcane larvae. Sugarcane response to feeding was recorded as damage symptoms, tiller production, number of millable stalks, and sugarcane and sucrose yield. Infestation at 3-leaf stage resulted in more dead hearts and dead plants than when infested at 5- and 7-leaf stages. The sugarcane variety CP89-2143 was more sensitive to E. lignosellus damage and resulted in reduced sugarcane and sucrose yield compared with CP78-1628 and CP88-1762. All varieties infested at the 3-leaf stage produced more yield than when infested at the 7-leaf stage. Comparison of yield reduction with the E. lignosellus lethal damage (dead hearts + dead plants) showed these varieties had equal ability to compensate for feeding damage, but that compensation ability declined with the delay in infestation time.;Field studies were conducted in 2006 to determine the effects of harvest residue from green harvesting versus pre-harvest burning on E. lignosellus damage and sugarcane yield. Harvest residue removed from a green harvested field and placed in plots in a plant cane field resulted in significant reduction of E. lignosellus damage. Sugarcane (TCA) and sucrose (TSA) yields did not differ between plots with and without harvest residues in plant or ratoon sugarcane. Three post-harvest tillage levels were tested in green and pre-harvest burned fields in 2008 and 2009. Significantly less E. lignosellus damage was observed in green versus pre-harvest burned fields in both years. No- and intermediate-tillage significantly reduced damage compared to conventional tillage in green harvested fields only. In both years, greater TCA was produced in intermediate than other tillage levels in green harvested sugarcane, whereas TCA and TSA were greater in conventional than other tillage levels in preharvest burned sugarcane.;These studies provide information useful for E. lignosellus population prediction and discovered the variety and age specific nature of sugarcane damage by this pest. Field studies showed the positive effects of green harvesting and intermediate tillage for reducing E. lignosellus damage and increasing sugarcane yield.