- Author: Shimat Villanassery Joseph
Bagrada bug (Bagrada hilaris) (Figure 1), an invasive stink bug species native to old world countries of southern Africa, Middle East and Asia, was first detected in North America from Los Angeles Co, California in 2008, and is now established in brassica crop production regions of central coast of California.
Bagrada bug prefers cruciferous hosts (Family: Brassicaceae) including broccoli, cauliflower, cabbage, kale, arugula, or collards. Also, bagrada bug could survive on cruciferous weeds such wild radish, London rocket, short pod mustard, and shepherd's purse, as well as the insectary plant, sweet alyssum. Mustard weed species are very common in ditches, roadsides, and along the edges of agricultural fields in the central coast of California. Mustard cover crops such as white mustard and Indian mustard in particular, could harbor bagrada bug populations, which are not often monitored for insect pests.
Damage to brassica crops varies but can be severe. Severe economic loss has been reported when injury occurred during early developmental stages of the crop such as cotyledon or < 4 leaves stages. Injury on leaves appears initially as small puncture marks, which turn into white patches as leaves expand. In broccoli and cauliflower, the economic injury occurs when the bug feeding kills the apical meristematic tissue of young seedling, which later results in “multiple heads” or sometimes “blind head” (without a head). Severe feeding also depletes the nutrient reserves of the plant leading to desiccation or wilting. Other leafy brassica crops such as mizuna mustard or arugula are especially at risk from direct feeding damage of bagrada bug.
At this time, no baseline information on bagrada bug abundance, seasonal activity, or generations has been established in the coastal brassica crop production regions in California. Limited information exists to determine threshold based pest management decisions for bagrada bug. Monitoringfor bagrada bug during mid-day hours might increase the probability of finding them as the bugs typically hide and stay in the cracks and crevices or on the underside of leaves when the temperature is cooler. Strong attraction to specific color could be utilized when developing selective traps for monitoring bagrada bug in the field. Yellow traps are most commonly used for monitoring true bugs such as false chinch bugs, plant bugs, psyllids or stinkbugs. Yellow pyramid traps were used to monitor brown and dusky stink bugs.
This study was conducted to determine the influence of trap color on catches of bagrada bug. In fall 2013, an organically-managed broccoli field in San Ardo, CA was chosen for the study. Planting sweet alyssum is a common practice among organic growers in the Salinas Valley to harbor beneficial insects such as syrphid flies (hover flies) and lady beetles within the cole crop field. Strips of sweet alyssum were planted within the broccoli field. Cross-vane traps were constructed using corrugated plastic sheets and were painted with white, yellow, red, purple, or black paint (Figure 2). All the trap-base containers used in this study were light green colored. Traps were placed within the sweet alyssum plants (Figure 3).Bug captures were recorded for up to 5 weeks.
In total, 10,654 bagrada bug were captured and were predominantly adults (95%). Adult bagrada bug captures were influenced by trap color (Figure 4a). Black traps captured almost twice the number of adult bagrada bug than purple traps; however, adult catches were similar among purple, white or red traps. Catches of adults were higher in purple than in yellow traps. Similarly, the numbers of bagrada bug nymphs collected among various colored-traps were higher in black traps than other colored traps (Figure 4b). Future research will investigate the potential use of color preference with plant host odor to develop traps for field monitoring of bagrada bug
For those of you, who are interested to read more on it, please find the published article after clicking the link (below) and feel free to contact me (Shimat Joseph) at svjoseph@ucanr.edu or 831 759 7359.
http://cemonterey.ucanr.edu/files/195965.pdf
- Author: Tunyalee Martin
UC IPM’s new Pest Alert helps you identify Bagrada bug, an invasive stink bug spreading through western Arizona and southern California causing severe crop, nursery, and landscape losses. In agriculture, Bagrada bug is a pest of cole crops and other mustard family plants. In home gardens it feeds on these same vegetables and on ornamental plants such as sweet alyssum and candytuft.
Bagrada bugs use their needlelike mouthparts to pierce and feed on plants and their seeds. Damage includes leaf spotting, wilting, stunting, multiple branches or crowns, and death of the whole plant.
The Pest Alert was produced by UCCE advisors Eric Natwick and Surendra Dara, John Palumbo from the University of Arizona, and the UC IPM team.
Preliminary agricultural management information is also available.
- Author: Shimat Villanassery Joseph
- Author: Richard Smith
Bagrada bug, Bagrada hilaris is now well established in the southern region of the Salinas Valley. This invasive stink bug, if left unmanaged, could become a serious pest of brassica crops. We studied their occurrence on cover crop, a mustard cover crop blend, broccoli and surrounding weed species, and would like to report few observations.
1. Cover crop, mustard
We observed significant populations of bagrada bug on 4-5 week-old mustard cover crop blend (Brassica juncea and Sinapis alba) in San Ardo. Interestingly, the adjacent field was also cover cropped with mustard but was disced few weeks ago. It is likely that the previous adjacent mustard crop might have had a bagrada bugs infestation and they moved to new planting when it was disced. When we walked into mustard stand from the disced field, we noticed that number of bagrada bug numbers declined from the field edge to the interior of the field. To understand better, a border zone (edge of the field), interior zone (90 feet into the field), and intermediate zone (between border and interior zones) were designated. Within each zone, six spots (~ 5.6 feet) were randomly selected and number of bagrada bugs was quantified after spending two minutes per spot. Similarly, two weed species and one native shrub surrounding the mustard field were randomly selected and number of bagrada bugs on them was counted after spending about one minute per plant.
Bagrada bugs tend to be more abundant on the edge of field than interior zones of the field (Fig. 1). It seems that bugs settled on the border plants of the field rather aggressively moving into the field. All life stages were detected. Most of the adults were in the mating position (connected by the rear ends) but very mobile. The adults tend to hide into the soil or under the leaves when we approached the infested plants.
Among the weed species investigated, bagrada bugs were only found on short pod mustard (Fig. 2 and 3). Other weed species investigated were shortpod mustard (Hirschfeldia incana), common purslane (Portulaca oleracea), lambsquarter (Chenopodium album), and the native shrub coyote bush (Baccharis pilularis). It is interesting to note that shortpod mustard plants were senescing, yet we found bagrada bugs on them.
2. Broccoli
The broccoli field was located in San Ardo adjacent to the Salinas River. The riparian plant community along the river contained stands of perennial pepperweed (Lepidium latifolium) as well as other species. Bagrada bug infestation was severe on pepperweed (Figs. 4a, and b).
Bagrada bug feeding injury symptom on broccoli plants was clearly visible on plants along the edge of the field. Feeding injury symptoms on broccoli include leaf distortion, chlorotic patches along the leaf margin and stunting (Fig. 5). Again, feeding symptoms drastically declined and/or plant vigor improved as we walked few steps (~ 10 feet) into the broccoli field from river side. Both nymphs and adults of bagrada bug were active along the edge of the field.
These preliminary observations indicate that some plants in the mustard family are highly attractive to bagrada bug. Shortpod mustard is a common summer-growing species that is commonly found on roadsides, in vineyards and in rangeland. Perennial pepperweed is an invasive plant that is commonly found in the riparian strip along the Salinas River. Both plants provide sufficient food resources for bagrada bug to successfully breed. After the onset of the winter rains, other mustard family weed species such as field mustard (Brassica rapa), black mustard (B. nigra), London rocket (Sisymbrium irio) and wild radish (Raphanus sativus) will begin their growth cycle. These plants are very common along roadsides and in ditches and may also provide over wintering habitat for bagrada bug.
- Author: Shimat Villanassery Joseph
Bagrada bug, Bagrada hilaris is an invasive stink bug and is moving North from the Southern Counties of California, rapidly than anticipated. In the past weeks, I have detected huge populations of these stink bugs on Indian mustard (cover crop), broccoli raab and kale in the King City and San Ardo areas. It is more likely that low populations exist in the other parts of the Salinas Valley.
It is well known that bagrada bug prefers cruciferous hosts (Family: Brassicaceae) including broccoli, cauliflower, cabbage, kale, arugula, collards, and Indian mustard. Major crops, lettuce and spinach are NOT a suitable host for bagrada bug. Also, these bugs can survive on cruciferous weeds such as mustard species (Brassica sp), wild radish, London rocket, short pod mustard and shepherd’s purse, as well as the insectary crop sweet asylum or sunflower. Mustard weeds species are very common in the Salinas Valley along ditches, roadsides and even along the edges of agricultural fields. Mustard cover crops such as white mustard (Sinapsis alba) and Indian mustard (Brassica juncea) in particular, could harbor bagrada bug populations which are not often monitored for pests.
Bagrada bug adult could be easily confused with harlequin bug. Adult of harlequin bug is orange with black and white marks, whereas bagrada bug adult is black with orange and white marks; and adult harlequin bug is about 3 times larger than bagrada bug. Eggs of harlequin bug are white with horizontal, black strips, whereas bagrada bug has no strips but has a “dirty” white appearance.
Damage to brassica crops is varied but could be severe. Severe economic loss has been reported when injury occurred during early developmental stages of the crop such as coldyledon or < 4 leaves stages. Injury on leaves appears initially as small puncher marks, which turn into white patches as leaves expand. In broccoli and cauliflower, the economic injury occurs when the bug feeding kills the apical meristematic tissue of young seedling, which later result in “multiple heads” or sometimes “blind heads” (without a head). Severe feeding also depletes the nutrient reserves of the plant leading to desiccation or wilting.
At this time, monitoring for bugs is the key. Monitoring for bagrada bug during mid-day hours might increase the probability of finding them as the bugs typically hide and stay in the cracks and crevices or on the underside of leaves when the temperature is on the cooler side. Cruciferous weeds in the drains, river bottoms, edges of the field or near residential area increase the risk of establishment. Do not forget to check the brassica cover crops for bugs as well.
Based on the insecticide efficacy studies conducted in University of Arizona, bifenthrin and methomyl were most effective in reducing bagrada bug infestation and injury on broccoli. For organic growers, none of the products were efficacious but pyrethrin and azidirachtin are suggested.
If you detect bagrada bug in Monterey, Santa Cruz and San Benito Counties, please do not hesitate to contact me (Shimat Joseph) at svjoseph@ucdavis.edu or (831) 759-7359.
Further reading:
http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=9023
Video (by Surendra Dara): http://youtu.be/gSj3AZoJIRM
- Author: Shimat V. Joseph
| Bagrada bug, Bagrada hilaris (Fig. 1) is an invasive stink bug native to old world countries of southern Africa, Middle East and Asia. It was first detected in Los Angeles County, California in 2008, now well established in Ventura, Los Angeles, Orange, San Bernardino, Riverside, San Diego and Imperial Counties, but recently detected in Santa Barbara and San Luis Obispo Counties. Also, it is a serious pest and has been detected in 4 more states (Arizona, New Mexico, Nevada and Utah) in the U.S. |  |
ATTN: Recently, bagrada bug adults were found on Chinese or napa cabbage in Santa Cruz County.
Although this bug feeds on a wide range of hosts, we are more concerned because the bug prefers cruciferous hosts (Family: Brassicaceae) including broccoli and cauliflower, which are grown as rotation crops in the Salinas Valley. It is believed that other major crops especially lettuce and spinach are NOT a suitable host for bagrada bug. At the same time, bagrada bug can survive on cruciferous weeds such as mustard species (Brassica sp), wild radish, London rocket, short pod mustard and shepherd’s purse, as well as the insectary crop sweet asylum. Mustard weeds species are very common in the Salinas Valley along ditches, roadsides and even along the edges of agricultural fields. Other species of mustards such as white mustard (Sinapsis alba) and Indian mustard (Brassica juncea) are grown as cover crops. It is clear that given the abundance of mustard family weeds and crops, there is a readily available source of habitat for this insect in the Salinas Valley.
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Bagrada bug adult is often confused with harlequin bug. Adult of harlequin bug is orange with black and white marks, whereas bagrada bug adult is black with orange and white marks; and adult harlequin bug is about 3 times larger than bagrada bug (Fig. 2). Eggs of harlequin bug are white with horizontal, black strips, whereas bagrada bug has no strips but has a “dirty” white appearance.
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It is believed that bagrada bug overwinters as adult in the cracks and crevices in soil or on plants. Generally, female bug is larger in size than male. Eggs are laid on the underside of leaves, cracks and crevices in soil or on hairy stems. There are five nymphal stages for bagrada bug. Typically, bagrada bug is found in aggregation with various nymphal stages and adult rather than individuals (Fig. 3). Because Salinas Valley has relatively mild temperature through year, it is expected that the development of bagrada bug would be prolonged compared with its populations in the warmer regions where it has been established. This also indicates that, if the bug is established, the number of generations of bagrada bug would be fewer in the Valley than in the warmer locations such as southern California or in the desert regions. Normally, its population size is small during early spring to mid-summer but eventually increases in size during later summer or fall.
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Damage to host plant is varied but could be severe. Severe economic loss has been reported when injury occurred during early developmental stages of the crop such as coldyledon or < 4 leaves stages. Injury on leaves appears initially as small puncher marks, which turn into white patches as leaves expand (Fig. 4a). In broccoli and cauliflower, the economic injury occurs when the bug feeding kills the apical meristematic tissue of young seedling, which later result in “multiple heads” (Fig. 4b) or sometimes “blind heads” (without a head). Severe feeding also depletes the nutrient reserves of the plant leading to desiccation or wilting. |
At this point, preventing the dispersal of bagrada bug to the Salinas Valley is the key strategy. Growers often move plant materials including transplants to the Valley for production from the regions where the bug has been established. Special care should be given to inspect the plant materials while moving them. Monitoring for bagrada bug during mid-day hours might increase the probability of finding them as the bugs typically hide and stay in the cracks and crevices or on the underside of leaves when the temperature is on the cooler side. Cruciferous weeds in the drains, river bottoms, edges of the field or near residential area increase the risk of establishment. Based on the insecticide efficacy studies conducted in University of Arizona, pyrethroids and neonicotinoids are effective in reducing bagrada bug infestation and injury. For organic growers, none of the products are efficacious but pyrethrin and azidirachtin are suggested.
If you detect bagrada bug in Monterey, Santa Cruz and San Benito Counties, please do not hesitate to contact me at svjoseph@ucdavis.edu or (831) 759-7359.
For more reading, please visit the links:
http://cisr.ucr.edu/bagrada_bug.html
http://www.plantmanagementnetwork.org/pub/php/brief/2010/bagrada/
