Influence of Herbivore-damaged Corn and Cotton in the Field Recruitment of Braconid Parasitoids from Feral Populations

The potential to increase parasitism by Cotesia marginiventris through response to chemical signals emitted by herbivore-damaged plants was investigated in corn and cotton field plots. Recruitment of feral C. marginiventris adult females was measured by increased parasitism. Spodoptera frugiperda larvae placed in the field plots and then recollected experienced a mean rate of parasitism of approximately 4-6%. Mean total mortality of the collected larvae ranged from 13 to 20%. We found no significant difference in the level of parasitism, or larval mortality between field plots containing herbivore-damaged plants and plants that were undamaged. Under the conditions of this study, we found no evidence that systemic host plant volatiles induced by herbivore feeding were used by feral C. marginiventris to improve foraging and parasitism at specific sites within a field of corn or cotton.