Injury Caused by Western Tarnished Plant Bug (Hemiptera: Miridae) on Broccoli and Cauliflower in Laboratory Assays

The polyphagous Lygus hesperus Knight is a serious pest on many crops in the western USA, including California’s central coast. Although L. hesperus adults can cause damage to broccoli and cauliflower, symptoms from their interactions with these plants are not fully characterized. Characterizing the feeding and ovipositional damage will help in the early diagnosis of the problem in the field and in greenhouses. Thus, the objective of this study was to characterize the feeding and ovipositional injury symptoms in broccoli and cauliflower after exposing 0, 1, 3, 5, and 10 adult L. hesperus to seedlings of broccoli and cauliflower for 24 h, 48 h, and 7 d. Although distorted and “blind” shoots were observed, feeding injury did not rapidly manifest into damage after 7 d post-exposure with high counts of adults on broccoli and cauliflower seedlings. The ovipositional injury was expressed as lesions that developed rapidly with a high density of adults in 24 h. The same levels of damage were observed with three or five adults to these hosts in 48 h. Significant positive correlations between the total eggs and lesions developed were observed on broccoli and cauliflower seedlings. After adult L. hesperus exposure, the growth of broccoli seedlings was reduced, but there was no effect on the growth of cauliflower seedlings. For diagnosis, data show that lesions are associated with adult L. hesperus ovipositional activity on these crops, which recommends thorough scouting and immediate application of plant protectants to reduce potential crop loss in greenhouses and in the field.