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Workgroup/Department: Plant Sciences

UNIVERSITY OF CALIFORNIA

DIVISION OF AGRICULTURAL SCIENCES

R E S E A R C H R E P O R T

Project Year: 2017-18 Anticipated Duration of Project: 1 year

Project Leader: Jhalendra Rijal, IPM Advisor (San Joaquin, Stanislaus, Merced Counties)

Location: UCCE Stanislaus, 3800 Cornucopia Way, Ste. A, Modesto, CA 95358

Cooperating Personnel: Roger Duncan, Pomology Farm Advisor, UCCE Stanislaus

Project Title: Monitoring of Brown Marmorated Stink Bug (BMSB) in the Northern San

Joaquin Valley Peach Orchards

Background:

The brown marmorated stink bug (Halyomorpha halys) (BMSB) originated in East Asia and

was first identified in the US in Pennsylvania in 2001, and has now spread to over 40 states

(www.stopbmsb.org). In 2010, BMSB caused about $37 million in damage to fruit crops.

BMSB has a host range of over 170 species, including virtually all fruit crops and vegetables

with fruiting structures. Peach is one of the preferred hosts of BMSB and rated as a high-risk

crop (http://www.stopbmsb.org/where-is-bmsb/crops-at-risk/). Adult and all nymphal stages

can damage fruits. Physical damage to fruits includes surface deformation/depression,

pitting, and scarring, sometimes leading to a mealy texture in the fruit. BMSB feeding injury

on young and mature peach fruit can develop discolored necrotic areas inside the fruit

(Leskey et al. 2012b). This makes the fruit unmarketable as a fresh or canned product. BMSB

usually produce one or two generations per year in cooler climates and up to five generations

in warmer climates (Lee et al., 2013; Nielsen and Hamilton, 2009).

In California, a large BMSB population was discovered in Midtown Sacramento in early

Sept. 2013, and subsequent surveys (http://cesacramento.ucanr.edu/files/217834.pdf) showed

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that they now infest downtown, midtown and other several locations in Sacramento County

(http://ccag-eh.ucanr.edu/Brown_Marmorated_Stink_Bug/BMSB_Finds/). Established

populations have now been documented in Butte, Sutter, Yolo, Sacramento, San Joaquin,

Santa Clara, Los Angeles, and most recently in Siskiyou and Stanislaus Counties (Lara et al.

2016). In November 2016, BMSB was detected in an urban area in Merced, Merced County

(Personal communication, Merced County Ag. Commissioner Office). In Stanislaus for the

first time, we (Jhalendra Rijal and Roger Duncan) have detected a reproducing population of

BMSB (i.e. several batches of egg mass, different stages of immature, and adult) in a group

of Trees of Heaven (i.e. Ailanthus sp), one of the favorite hosts, near Highway-99 in Modesto

during July 2015 (http://www.modbee.com/news/article30007908.html). Following the first

detection, we have received unofficial reports of finding BMSB at least in four locations in

Modesto and nearby cities, Turlock and Empire in 2015. In one instance during the late fall

2015, a live adult BMSB was found near a house next to a peach orchard east of Empire

which is ~7 miles east of the Highway-99. In fall 2016 and 2017, there have been multiple

reports of BMSB invading houses and other structures surrounded by active agricultural

areas in Stanislaus County.

In 2016 season, we conducted BMSB detection survey in nine cling peach orchards located

in Stanislaus and Merced Counties from last week of April through mid-November. Standard

black pyramid traps (4 ft. tall, Dead-Inn Traps, AgBio, Inc.) baited with the BMSB lure were

used for this study in nine peach orchards located. BMSB adults were captured from one of

the nine peach orchards surveyed. On July 5, 2016, One BMSB adult was captured in a peach

orchard ~9 miles east of the first BMSB finding site near Highway 99, Modesto. After that,

we increased the trap numbers, four traps baited with the Trécé lure and four traps baited

with the Alpha Scents lure. Traps were placed along the edges of the peach orchard.

Beginning mid-September, we started catching BMSB. The highest mean capture was on 17

October in which 2.5 adults/trap/week for Trécé lure, and 0.75 adults/trap/week for Alpha

Scents lure were captured. The total number of adults captured in four Trécé and four Alpha

Scents lures were 23 and 7, respectively, and that was the first report of consistent BMSB

captured from any agricultural crops in California (Rijal and Duncan 2017). The study

clearly showed that a BMSB population has been established in and/or nearby peach

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orchards in Stanislaus County. Given that peach is one of the preferred hosts of BMSB, it is

critical to continue monitoring and damage assessment studies on BMSB in the northern San

Joaquin Valley area. In order to increase assurance of discovering BMSB presence before it

has built up large numbers, we propose to continue BMSB monitoring and damage

evaluation work in cling peach growing area of Stanislaus County.

Objectives for the 2017 season:

1. Conduct a BMSB detection survey in peach orchards in Stanislaus County, using

traps, and visual samples.

2. Conduct season-long insect monitoring and fruit damage assessment in the peach

orchards.

3. Extend information to local growers and pest control advisors through semi-monthly

IPM breakfast meetings, blog postings and field days.

Plans and Procedures

BMSB monitoring. Two types of traps (pyramid and sticky panel) were used to monitor

BMSB activities in selected peach orchards. Both types of traps were baited with the most

improved BMSB lure (BMSB aggregation pheromone + methyldecatrionate, MDT) available

to date. The pyramid trap (Fig. 1) has been the standard BMSB trap, but this trap is expensive

and more cumbersome for field use. So, this year, along with other researchers working on

BMSB from other parts of the Country, we also tested the new trap type ‘sticky panel trap’

(Fig. 2). Eight traps (four of each trap type) separated by at least 50 ft were placed in total

four peach orchards along the edges of the orchard. Traps were placed around mid-March in

two commercial sites (Orchard #1 & #2), the first week of May at UCCE site (Orchard #3),

and mid-July at CSU-Stanislaus (Orchard #4). Later two orchards were not maintained for

the commercial purpose, therefore, received minimal insecticide and other inputs. These two

sites, traps were placed after the BMSB activity was reported. Two commercial sites were

within the area where BMSB was detected in 2016-study. Traps were checked and serviced

as needed basis and lures were changed at 4-week intervals in all sites.

Visual inspection of trees for the presence of BMSB. Trees that are near to the traps were

inspected for the presence of any life stages of BMSB throughout the monitoring period.

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Peach fruit evaluation for damage. In early May, we collected young fruits from two

commercial orchards and inspected for the damage. At Orchard #3, after observing the

BMSB adult activity in traps and spotted BMSB adults, eggs, and nymphs on trees during the

summer, we collected fruits and evaluated for the BMSB damage during harvest. Matured

fruits that were ready-to-ripe were evaluated around the third week of July. The UCCE

orchard is ‘demonstration orchard’ with a different mixture of peach varieties, rootstocks,

pruning system, etc. The fruits of representative varieties (Tuolumne, Stanislaus, RHSV,

Early 3, O’Henry) were collected from multiple trees and inspected for the external and

internal damage by BMSB by cutting the fruits into slices.

Results and Discussion

Trap-based monitoring. In all sites, the majority of the captures were from the beginning of

the season (March-May), likely overwintering adults. In two commercial sites, although total

seasonal was low, BMSB adults were caught between 12 April – 9 May in Orchard #1 (Fig.

3), and between 26 April-30 May in Orchard #2 (Fig. 4). Sticky panel traps caught more

BMSB than the pyramid traps in both sites. No nymph was captured from the two

commercial orchards. No adult was captured beyond the first generation captures in

commercial orchards. There might be three reasons for that. First, as the peach fruit ripens,

BMSB likely to be attractive to the fruits more than the traps, and this is true for trapping in

peaches in the Mid-Atlantic States as well (T. C. Leskey, personal communication). Second,

the insecticide use in commercial orchards targeting other stink bugs, and Lepidoptera pests

such as Oriental fruit moth, peach twig borer might have also control BMSB especially given

the overall low population of BMSB in commercial orchards. Third, consistently high

temperature (>100 degrees F) multiple days during the summer might have killed the BMSB

population significantly especially the younger nymphs, although both nymphs and adults

were captured from the Orchard #3 during July and later dates.

In Orchard #3, traps were placed around the end of April and started catching adults from

that week (2 adults/trap/week). Adults were captured during July and peaked between last

week of September and the first week of October (Fig. 5). There were three distinct nymph

captures (9 June, 18-25 July, and 23 Aug-1 September), although the total number of the

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captures for each peak was not high (Fig. 5). Comparing sticky panel and pyramid traps,

numerically greater number of adults were captured in the sticky trap (36 adults) compared to

the pyramid trap (28 adults). In contrast, a greater number of nymphs (5 nymphs) were

captured in the pyramid trap than the sticky trap (2 nymphs) (Fig. 6). In Orchard #4, traps

were placed around mid-July. Between July and 19 October, highest average adult counts

were captured on 5 October (2.33 adults/week), followed by 27 September (2.00

adults/week) (Fig. 7).

Visual inspection of trees. No BMSB was found by visually looking at peach trees adjacent

to traps from two commercial sites. At Orchard #3, we surveyed total 38 trees on 19th July

spending about 5 minutes for each tree and recorded total 4 adults, 6 nymphs, and 2 egg

masses. One late-stage nymph (4-5th instar) was detected in one peach tree at CSU, Turlock

site during mid-July.

Peach fruit evaluation for damage. In early May, we collected some young fruits from the

two commercial orchards and inspected for the damage. Total 95 and 100 fruits were

collected representing 4 pyramid trap locations from Orchard #1 and Orchard #2,

respectively, brought them to the lab and inspected for the damage (external and internal)

potentially by the stink bugs. In Orchard #1, there was the evidence of pin-hole damage,

water-soaked lesion, and some necrotic lesions. About 10.5% of fruits had had some type of

true bug feeding damage, although, on this site, we did not notice multiple feeding sites and

lesions within the fruit, which are typical signs of BMSB feeding (Fig. 8). In Orchard #2

where more than 30 adults were captured in the Fall 2016, about 12% young fruits showed

BMSB feeding signs (i.e., cork-spots and necrotic lesions) on young fruits (Fig. 9). These

type of feeding injury look similar to what was described by Leskey et al. 2012 (Fig. 10).

Although we did not conduct the harvest damage evaluation systematically, we evaluated

overall fruit health before the harvest by walking into the orchard and inspecting fruits for the

damage. We did not see much noticeable damage on fruits. The reason might be that most of

the infested young fruits might have been dropped naturally by then and/or thinned out

during the thinning practice. The late-season infestation might not have been significant due

to no BMSB activity based on the trap catches from mid-June through October this year.

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At Orchard #3, peach fruits were collected from five different varieties. All varieties were

about the same stage of ripening. The fruits were inspected for external and internal damage.

The damage in the fruit was categorized into five categories that include external (gumming,

depression) and the presence of internal lesions (water-soaked, necrotic, and cork-like) (Fig.

8). The average percent damage by stink bug for five varieties was presented in the table

below. It is important to note that, the orchard was not sprayed timely for insect control, and

there likely to be infestation by other stink bugs as well.

Peach Variety

Total #

fruits (N)

% Damage on fruits collected

Overall damage

Surface depression

Surface gumming

Necrotic lesion

Cork-like

lesion

Water-soaked Lesion

Tuolumne 48 65.77 58.7 1.67 26.5 16.8 22.2

Stanislaus 25 20.00 45.0 0.00 35.0 20.0 40.0

RHSV 22 45.00 20.0 2.50 15.0 7.5 17.5

Early 3 6 85.70 85.7 0.00 0.0 100.0 14.3

O'Henry 12 28.90 27.5 8.33 30.6 44.4 8.3

Conclusions

This study clearly showed that the BMSB population had been established in agricultural

areas in the northern San Joaquin Valley particularly in Modesto Metropolitan area, and other

nearby agricultural towns. We also begin to see the BMSB damage in agricultural areas and

the population has been spreading into the new areas every year. In a separate study, we

discovered BMSB reproducing populations for the first time in two almond orchards in 2017

growing season with the considerable amount of feeding damage. Local pest control advisers

have reported the findings of BMSB with a significant injury to the nuts from additional two

almond orchards, one of them was located more than 15 miles west of the first BMSB

detection site near highway-99, Modesto. Sightings of BMSB have also been reported from

the peach orchards in the Fall of this year after the harvest. Given that BMSB host crops,

peaches, cherries, and now almonds are in close proximity to each other and are often within

the same farm, the risk of BMSB to these crops has been increased.

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Another significant finding from this year work was the use of more convenient trap type for

BMSB monitoring. In general, we did not see any difference in catching BMSB adults in

sticky panel traps, compared to the standard pyramid traps, in some cases even better capture

in sticky panel traps. Given that the sticky panel traps are effective but far cheaper and easier

to use, we recommend using sticky panel traps for BMSB adult monitoring in peach and

other fruit and nut crop orchards. We will continue our work in optimizing the trap types in

the future.

At this point, it is critical that growers and pest control advisers (PCAs) pay close attention

when monitoring fruit orchards for BMSB presence and potential damage. Early monitoring

is very important, especially if the orchard is near to the areas with known infestations and/or

areas with known tree hosts such as the tree of heaven. Visual observations of insects (egg

masses, nymphs, adults) and damaged fruit (deformed fruits, fruits exuding gum) and beat

tray sampling (shaking branches/twigs to dislodge insects) are early BMSB detection

methods. Also, placement of a few BMSB pheromone traps in the border rows of the orchard

beginning from March is recommended to detect BMSB activity and infestation. Future

research will focus on understanding the phenology, crop damage assessment, optimizing

monitoring tools and exploring control options for BMSB in California.

The results of the BMSB study have been used to educate residents, growers, and other pest

control professionals using several extension meetings (IPM breakfast and other extension

meetings including annual cling peach day meeting), newsletters (link) and peer-reviewed

publications, blogs (IPMCorner.com). Here are some examples of BMSB publications.

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Figures

4 ft.

Fig. 1. Black pyramid trap used in BMSB

monitoring.

Pheromone

lure

Insecticide

strip

Fig. 2. Clear ‘sticky panel’ trap

used in BMSB monitoring.

Pheromone

lure

9

0.0

1.0

2.0

3.0

4.0

5.0

6.0

14-M

ar

20-M

ar

28-M

ar

4-A

pr

12-A

pr

19-A

pr

26-A

pr

2-M

ay

9-M

ay

16-M

ay

23-M

ay

30-M

ay

6-J

un

16-J

un

20-J

un

28-J

un

5-J

ul

11-J

ul

18-J

ul

Fig. 3. Total weekly BMSB adults (total from 4 traps) captured in a commercial peach orchard #1, Modesto, CA

Pyramid Sticky Panel

0.0

1.0

2.0

3.0

4.0

14-M

ar

20-M

ar

28-M

ar

4-A

pr

12-A

pr

19-A

pr

26-A

pr

2-M

ay

9-M

ay

16-M

ay

23-M

ay

30-M

ay

6-J

un

13-J

un

20-J

un

28-J

un

5-J

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11-J

ul

18-J

ul

28-J

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21-M

ar

15-A

ug

23-A

ug

28-A

ug

12-S

ep

20-S

ep

26-S

ep

3-O

ct

10-O

ct

Fig. 4. Total weekly BMSB adults (total from 4 traps) captured in a commercial peach orchard #2, Modesto, CA

Pyramid Sticky Panel

10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

3-M

ay

10-M

ay

17-M

ay

26-M

ay

30-M

ay

9-J

un

15-J

un

28-J

un

5-J

ul

18-J

ul

25-J

ul

3-A

ug

9-A

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16-A

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23-A

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1-S

ep

8-S

ep

13-S

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20-S

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26-S

ep

5-O

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11-O

ct

19-O

ct

Avera

ge B

MS

B a

dtu

ls/tra

p

Avera

ge B

MS

B a

dtu

ls/tra

p

Fig. 5. Weekly average BMSB capture (per trap) in combined sticky and pyramid traps in peach orchard at

UCCE, Modesto, CA

Adult Nymph

0

5

10

15

20

25

30

35

40

Pyramid Sticky Pyramid Sticky

Adults Nymphs

Fig. 6. Total seasonal BMSB capture (N = 4 traps) in pyramid and sticky panel traps at Orchard #3, Modesto, CA

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

20-J

ul

26-J

ul

3-A

ug

9-A

ug

16-A

ug

23-A

ug

1-S

ep

8-S

ep

13-S

ep

20-S

ep

27-S

ep

5-O

ct

10-O

ct

19-O

ct

Fig. 7. Average weekly BMSB adults captured in sticky panel trap in peach/nectarine orchard in Orchard #4

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Fig. 8. Stink bug feeding damage on young peaches in Orchard #1, Modesto, CA

Fig. 9. Stink bug feeding damage on young peaches in Orchard #1, Modesto, CA

Fig. 10. Examples of BMSB feeding sign on young peaches (Leskey et al. 2012)

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Fig. 11. BMSB feeding damage on

peaches: A) depression/sunken areas on

fruit surface, B) water soaked lesion, C)

cork-spot, D) necrotic tissues, E) whitish

disintegrated tissue beneath the fruit

surface

A B

C D

E

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Literature Cited

Lara J., C. Pickett, C. Ingels, D. R. Haviland, E. Grafton-Cardwell, D. Doll, J. Bethke, B.

Faber, S. K. Dara, and M. Hoddle. Biological control program is being developed for

brown marmorated stink bug. Cal. Ag. 70(1): 15-23.

Lee, D-H., B.D. Short, S.V. Joseph, J.C. Bergh, and T.C. Leskey. 2013. Review of the

biology, ecology, and management of Halyomorpha halys (Hemiptera: Pentatomidae) in

China, Japan, and the Republic of Korea. J. Environ. Entomol. 42(3):624-641.

Leskey, T.C. 2011. Emergence of brown marmorated stink bug, Halyomorpha halys (Stål),

as a serious pest of agriculture. Online presentation

(http://www.epa.gov/oppbppd1/biopesticides/nafta-workshop-slides/leskey-epa-nafta-

workshop.pdf).

Leskey, T. C., B. D. Short, B. R. Butler, and S. E. Wright 2012. Impact of the invasive brown

marmorated stink bug, Halyomorpha halys (Stål), in mid-Atlantic tree fruit orchards in

the United States: case studies of commercial management. Psyche: A Journal of

Entomology. doi:10.1155/2012/535062.

Nielsen, A.L. and G.C. Hamilton. 2009. Life history of the invasive species Halyomorpha

halys (Hemiptera: Pentatomidae) in northeastern United States. Ann. Entomol. Soc.

Amer. 102(4):608-616.

Rijal, J. P., and R. Duncan. 2017. First report of an established brown marmorated stink bug

(Hemiptera:Pentatomidae) population in California agricultural crops. J. Entomol. Sci.

52:450-454.