Investigation and characterization of changes in feeding preferences of the harlequin bug, Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae)

The Harlequin bug (HB) is a major pest of crucifers in southern United States. Feeding by the HB adults and nymphs feeding causes white blotches (necrosis) on the leaves making them unmarketable, thus reducing their economic value. Although, broad-spectrum insecticides are effective in controlling HB, they cause harm to the environment, natural enemies, and human health. Studies have shown the use of trap crop especially mustard has been effective in managing HB. The goal of our experiments was to determine the preference for different mustard varieties and the phenological stage most attractive to HB, and to characterize the underlying differences. We conducted three laboratory experiments: i) Dual-Choice Arena Test (DCAT) and ii) olfactometer test, and iii) a development study using four mustard varieties (‘OFM’, ‘FBL’, ‘SGC’, and ‘GR’) and a collard variety (‘GS’) at three phenological stages (early vegetative, late vegetative, and at bloom/flowering). We also analyzed the glucosinolates (GLS) content at each stage using spectroradiometer measurements with HPLC analysis. DCAT results indicated that mustard variety and phenological stage had significant effect on attraction and preference of HB within the different mustard varieties. FBL was most preferred and GR the least preferred at vegetative stages with OFM being most preferred at flowering. Olfactometer results revealed that harlequin bugs respond to volatiles emitted from the different varieties with highest response of 75% of HB to OFM. The discovery lends itself for use in developing a mustard trap model for management of HBs in collard and scalable to other crucifers.