Parasitoid presence and predation of sugarcane borer (Diatraea saccharalis Fabricius) eggs in sugarcane and APP (area of permanent preservation) fragments

Areas of permanent preservation (APP) may function as beneficial reservoirs of native parasitoids and predators of the sugarcane borer, Diatraea saccharalis (Fabricius).  Two sugarcane farms in north-central São Paulo state, Brazil were selected to research natural enemies in both sugarcane fields and adjacent APP fragments.  To establish parasitoid presence and evaluate D. saccharalis egg predation, we used control, predator-free, and with predator treatments.  Adult moths were placed in cages to deposit eggs on both sugarcane and grass leaves in the field and APP, respectively.  Pictures of the egg masses were taken to compare the percent loss of eggs over time.  Parasitoid presence was monitored by observing egg masses in the lab for 17 days.  To assess the diversity of a common predator, we collected ants using sardine baited cards and opportunistic sampling.  The mean percent loss of egg mass area after four days under field conditions showed that predator-free treatments had significantly less egg loss than the predator treatments (p < 0.01).  No interactions or differences were found between the sugarcane and APP samples.  Parasitoids emerged from three APP samples located at both farms.   We identified 17 ant morphospecies from 12 genera.  Significantly different Jaccard’s similarity index values were found when comparing the two farm’s ant assemblages (p < 0.01), but not between the APP and sugarcane samples.  This preliminary study indicates that parasitoids in APP areas and natural predators reduce D. saccharalis egg survival.  It also provides a baseline list of ants found in these habitats.