Dissertation

from a colony maintained year-round on artificial diet in the laboratory. The colony originatedfrom larvae collected in bermudagrass pastures near Baton Rouge in 1997. Insects collectedfrom pastures or rice fields are added annually to the colony to maintain genetic variability andvigor.Characterization of Induced Resistance Following Fall Armyworm Herbivory. Twoseparate experiments were conducted to assess whether resistance to L. oryzophilus was inducedby prior S. frugiperda herbivory. In the first experiment, the rice variety ‘Rosemont‘ was used,and in the second, ‘Jackson’ was used. These varieties were used because prior studies hadshown that they are very responsive to fall armyworm feeding and JA treatment (Stout et al.,2009). Rice seedlings were grown to the early three-leaf stage as described above. Pots werethen randomly assigned to two treatment groups, ‘control’ and ‘damaged.’ Plants were damagedby confining one fourth to fifth instar S. frugiperda larvae per plant using cages. Cages wereconstructed of clear plastic cylinders (8.5cm diameter, 23cm height) with one end inserted intothe soil and the top end covered with a mesh-screen lid. The cylinders had two mesh-lined holesto allow for air circulation. Larvae were allowed to feed for four to six hours, and on average,consumedbetween 20% and 30% of total leaf area, typically damaging portions of every leaf. Cages withno larvae were placed over plants assigned to the control group. Cages and larvae were removedfrom plants after four to six hours of feeding and plants were maintained in the greenhouse forlater evaluation of resistance to L. oryzophilus.Evaluations of resistance to L. oryzophilus were conducted approximately 13 to 15 daysafter injury by S. frugiperda. By this time a new leaf or, in some cases, two new leaves hademerged on both damaged and control plants. Four pots of each treatment were placed intoinfestation cages, which were constructed of cylindrical wire frames (46 cm diameter, 61 cm tall)16