Female harlequin bugs commute from a mustard host to a collard host to oviposit: Implications for management using trap crops

Harlequin bug (HB), Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae) is a major economic pest of cruciferous crops in the southern United States. Trap crops show promise as a cultural control, but development of a successful trap crop is a challenge.  We conducted lab and field experiments to investigate the effect of separation distance between a mustard trap crop and a collard cash crop on HB colonization. Greenhouse arenas, with mustard and collard plants at different distances from each other, tested HB residency, oviposition preference and “Field trap cropping experiments tested the effect of separation distance on pest retention by comparing numbers of different life stages on collard plots with an adjacent mustard border versus a separated mustard border. In both experiments, adults preferred to reside on mustard.  But egg masses and resulting nymphs were found predominantly on collard, and in the field experiment, the effect was much stronger within the collard plots with an adjacent mustard border, compared to those with more separation. Our experiments confirm the preference of adult HB for mustard, with the novel findings that ovipositing females commute to nearby collards to lay their eggs, an effect that is mitigated by physical separation of a perimeter trap crop.