Bagrada hilaris (Burmeister) 221
adults commonly move into newly established fields and begin feeding on the cotyledons and stems of
direct-seeded plants immediately following emergence of the hypocotyl (Palumbo and Natwick 2010,
Huang et al. 2013). Feeding on newly emerged cotyledons of brassicaceous host crops in the field can
result in rapid plant desiccation and death (Palumbo and Natwick 2010). In general, larger plants with
more leaf area are less susceptible to B. hilaris feeding injury than small seedlings. Under caged labora-
tory conditions, seedling (cotyledon stage) mortality in response to B. hilaris feeding occurred within a
few hours on several brassicaceous crop species (Huang et al. 2014a). Huang et al. (2014b) showed that
young brassica seedling plants (i.e., cotyledon stage) were significantly more susceptible to plant death
than larger 4-leaf stage plants. Laboratory studies further demonstrated that feeding damage caused by
B. hilaris significantly reduced leaf growth, chlorophyll content, and dry weights of broccoli, red and
green cabbage, and cauliflower (Huang et al. 2014b).
In leafy, non head-forming brassicaceous plants in which the leaves are produced for fresh mar-
kets (i.e., kale, arugula, collards), feeding injury similarly can reduce plant growth on young plants
(Nyabuga 2008; Huang et al. 2014a,b) and affect cosmetic quality throughout the growing season due to
the chlorotic and necrotic aesthetic damage to leaves at harvest (Palumbo and Natwick 2010, Reed et al.
2013b). In head-forming brassica crops, feeding injury or death to the terminal growing point will lead
to plant deformations such as adventitious bud break (plants produce multiple unmarketable heads) or
‘blind’ plants (no head produced) (Figures 3.1D, 3.7, and 3.8) (Palumbo and Natwick, 2010, Reed et al.
2013b, Sánchez-Peña 2014). Field studies in Arizona have shown that broccoli and cauliflower plants are
FIGURE 3.7 Blind cauliflower injury caused by feeding of Bagrada hilaris, Yuma, Arizona. (Courtesy of John C.
Pa lumbo).
FIGURE 3.8 Unmarketable multiterminal broccoli caused by feeding of Bagrada hilaris, Yuma, Arizona. (Courtesy of
John C. Palumbo).