Host Plant Resistance to Tarnished Plant Bug in Arkansas: III. Laboratory Evaluation

Field and laboratory trials have focused on developing evaluating techniques for screening cottons with host plant resistance to tarnished plant bug (TPB).  The field cage and main stem cuttings techniques show promise and could be helpful in evaluating TPB resistance of new cotton germplasm. We observed differences in 3-day plant bug nymph survival between resistant and lines when bugs were exposed to field grown cotton plants. These differences were not apparent with greenhouse grown plants. These results remind us that host plant resistance is relative, and the expression of resistance often is dependent on environmental factors.   Field cage tests were time and labor intensive. Use of cuttings method was easier, and much more appealing to research personnel. Use of newly hatched nymphs allowed greater separation among lines; however, use of such tiny, delicate insects required skilled and competent personnel.   Overall, we believe that these results show promise for further expanding the terminal cuttings HPR screening protocol. If the cuttings technique is confirmed, resistance of varieties and breeding lines could be compared by taking plant cuttings from existing field tests.  Also, cuttings could be made from segregating populations thereby allowing breeders to directly select for resistance to TPB. Further evaluations using additional cotton lines and with standardized handling of test insects are needed.