Journal of Integrated Pest Management, (2019) 10(1): 11; 1–6
doi: 10.1093/jipm/pmz006
Issue

Economic Impact of Spotted Wing Drosophila (Diptera:
Drosophilidae) Yield Loss on Minnesota Raspberry Farms:
A Grower Survey
Gigi DiGiacomo,1 Joleen Hadrich,1 William D. Hutchison,2,4 Hikaru Peterson,1 and Mary Rogers3
Department of Applied Economics, University of Minnesota, 1994 Buford Avenue, St. Paul, MN 55108, 2Department of Entomology,
University of Minnesota, 1980 Folwell Avenue, St. Paul, MN 55108, 3Sustainable & Organic Horticultural Food Production Systems,
Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, MN 55108, and 4Corresponding author,
e-mail: hutch002@umn.edu
Subject Editor: John Adamczyk
Received 1 November 2018; Editorial decision 14 February 2019

Abstract
Minnesota was dubbed the ‘raspberry consumption capital of America’ in 2017 by wholesaler Driscoll’s, Inc.
Local production of this high-demand fruit, however, is limited by the invasive pest, spotted wing Drosophila
(Drosophila suzukii Matsumura, Diptera: Drosophilidae). Recent research to develop integrated pest management
(IPM) programs for MN berry crops indicates that raspberry growers are particularly vulnerable to significant
spotted wing Drosophila-related yield losses. Spotted wing Drosophila was detected in Minnesota in 2012 across
29 counties. This analysis explores the economic impact of raspberry yield losses associated with spotted wing
Drosophila in Minnesota as part of a multifaceted research initiative. An electronic survey of 157 MN berry growers
was conducted in November 2017. Eighty-two individual grower surveys were returned (52% response rate). The
survey included questions about production acreage, marketing practices, spotted wing Drosophila-related yield
losses and future production intentions. The results of the e-survey indicate that raspberry growers have borne the
highest levels of infestation among MN fruit growers surveyed. Spotted wing Drosophila-related yield losses for
raspberry growers ranged from 2 to 100% of planted acreage.The median yield loss for this group of growers was
20% in 2017. Applying the median yield loss to ex-ante production estimates, we conclude that MN growers lost
approximately $2.36 million in raspberry sales during the 1 yr studied. Investing in spotted wing Drosophila control
measures will help MN growers reduce some of these losses in the future.
Key words: survey, spotted wing Drosophila, invasive fruit fly, raspberry yield loss

Raspberry consumption is on the rise nationwide and may offer
a promising seasonal niche for MN bramble growers looking to
market ‘locally-grown’. The Economic Research Service estimates
that fresh raspberry utilization has grown steadily nationwide
from 0.18 pounds per capita in 2007 to 0.86 pounds per capita
in 2016 (USDA, ERS). A  recent press release from Driscolls, Inc.
(Watsonville, CA), however, suggests that this utilization estimate,
while impressive, is undervalued for Minnesota. Drawing on Nielsen
Company data, Driscoll’s, Inc. reports that ‘Twin Cities’ households
(Minneapolis-St. Paul metro area) consumed 132% more fresh
raspberries on average than U.S.  households explaining why the
company named Minnesota ‘raspberry consumption capital of
America’ in July 2017 (Duan 2017).
Combining USDA raspberry utilization estimates with Nielson
data, we estimate that Minnesotans utilized approximately 5.6
million pounds of fresh raspberries and another 4.9 million pounds
of frozen raspberries in 2017. Fresh and frozen raspberries are

priced differently in wholesale and retail markets. However, due to
data limitations, we apply the USDA 2017 median retail price for
nonorganic raspberries, $6.70 per pound, to both fresh and frozen
raspberries. We estimate the annual retail value of statewide of fresh
and frozen raspberries at $70.6 million (value = utilization * price per
pound) (Table 1). Recognizing that the MN growing season (USDA
plant hardiness zone 3b-4a) is approximately 4 mo, we estimate
seasonal demand for fresh and frozen raspberries is 3.51 million
pounds valued at $23.5 million (Table 1). Minnesota growers’
potential to capture local, seasonal raspberry demand, however,
is limited by the recent invasive pest, spotted wing Drosophila
(Drosophila suzukii Matsumura,  Diptera: Drosophilidae), which
has been shown to favor raspberries as a host fruit (Asplen
et  al. 2015, Holle et  al. 2017) (Fig. 1). Spotted wing Drosophila
deposits eggs in raspberry druplets using a serrated ovipositor. As
larvae begin to grow, raspberry fruit degrade and become soft and
discolored, making them unmarketable (Figs. 2 and 3).

© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/),
which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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 Journal of Integrated Pest Management, 2019, Vol. 10, No. 1

2 
Table 1.  Raspberry utilization in Minnesota, 2017

Twin-cities MSAa

MN statewide

Populationb
Fresh raspberry utilization (lbs per person)

2,090,039
0.86

3,360,829

5,450,868

Fresh raspberry utilization (lbs)c
Frozen raspberry utilizationd (lbs per person)
Frozen raspberry utilization (lbs)
Annual raspberry utilization (lbs)

1,797,434

1.14f
3,831,345

5,628,779

0.90
1,881,035
3,678,469
6.70

0.90
3,024,746
6,856,091
6.70

4,905,781
10,534,560
6.70

24,645,742
1,226,156
8,215,245

45,935,809
2,285,364
15,311,938

70,581,552
3,511,520
23,527,184

Median Midwest nonorganic retail ($ per lb)e
Annual retail value ($)
Seasonal (4 mo) utilization (lbs)
Seasonal (4 mo) retail value ($)
a

The ‘Twin Cities’ is defined as the Minneapolis-St.Paul-Bloomington MN-WI Metropolitan Statistical Area (MSA).
Source: US Census Bureau, American Fact Finder, 2017 Population Estimates.
c
Source: USDA (2018b), ERS. ‘Table G-13-Fresh raspberry supply and utilization, 1992 to date.’ Fruit: US supply and utilization: fresh, canned, juice, dried; per
capita use, US population.
d
Source: USDA (2018c), ERS. ‘Table G-38-Frozen fruit, per capita use, product weight basis, 1980 to date.’ fresh, fruit and tree nut yearbook tables.
e
We recognize that fresh and frozen raspberries are valued differently. However, due to data limitations, we price them equally using USDA 2017 Midwest
median raspberry prices. Source: USDA (2018a), Agricultural Marketing Service, ‘Weekly Advertised Fruit & Vegetables Retail Prices.’
f
Neilson data suggests that ‘Twin Cities fresh raspberry consumption’ is 132% higher than national average per capita consumption. The MN Twin-Cities
consumption estimate was adjusted by 132% to arrive at the Twin-Cities per capita consumption estimate for fresh raspberries.
b

Table 2.  Estimated MN raspberry production, before spotted wing Drosophila detection

Baseline production
Certified organic
  Red, open field

2007 acres#

2008–2009 yield lbs/acre

Ex-ante productiond lbs

296

4,708

1,393,568

5a

1,307a

6,535

Nonorganic
  Red, open field

254

1,195,832

  Black, open field
  Red, high tunnel

13

4,708b
2,000

24c

22,253b

Adjusted production

296

26,000
534,072
1,762,439e

a
Raspberry production reported is assumed to be open-field. Source: ‘Table 25: Organic berries harvested from certified organic farms: 2008.’ 2008 Organic
Production Survey. USDA, National Agricultural Statistics Service.
b
Two-year-old, nonorganic plants produced in USDA hardiness zone 3b. Estimated based on 2009 data from field research at NCROC in Grand Rapids, MN.
Source: Yao and Rosen 2011.
c
Calculated using primary data from 2017 e-survey. High tunnel production estimated to be equal to 8.3% of nonorganic raspberry production. All high tunnel
production in 2017 was reported as nonorganic. The same production ratio was applied to ex-ante spotted wing Drosophila production years.
d
Production = acres*yield where yield is measured as pounds per acre.
e
Total MN production of organic and nonorganic raspberries.

Table 3.  Percent of MN fruit growers using alternative production methods

n = 82
Open field
High tunnel
Other

Raspberry growers

Strawberry growers

Blueberry growers

Other fruit growers

90%
8%
3%

90%
3%
8%

91%
5%
5%

100%
0%
0%

This analysis explores economic losses for MN raspberry
growers due to spotted wing Drosophila-related yield reductions.
Spotted wing Drosophila-related yield loss estimates have been
applied to raspberry production estimates to quantify the value of
these losses in California for nonorganic (Goodhue et al. 2011) and
organic raspberries (Farnsworth et al. 2017) using USDA production
data. Raspberry production (total pounds) is a function of acreage

(number of acres) and crop yield (pounds per acre). Yield is affected
primarily by plant variety (summer-bearing vs fall-bearing); plant
maturity (less than 3 vs 3 yr or more); growing conditions (openfield vs high tunnel [HT]); and management practices (organic vs
nonorganic), all else being equal. Data for nonorganic raspberry
production in Minnesota, however, are not compiled by USDA as
the state is considered a relatively small producer of bramble fruit.

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MN outstate

 Journal of Integrated Pest Management, 2019, Vol. 10, No. 1 

3

Table 4. Spotted wing Drosophila-related yield losses for fruit
crops reported by MN survey respondents

n = 82

Raspberries

Strawberries

Blueberries

Other

Median
Mean
Low
High

20%
30%
2%
100%

5%
13%
1%
90%

5%
16%
2%
54%

0%
17%
1%
100%

Table 5. Spotted wing Drosophila-related raspberry yield losses
reported by MN survey respondents

n = 28

Organic raspberries

Nonorganic raspberries

20%
27%

20%
25%

Median
Average

2011). This last assumption is supported by findings that berries from
other geographic areas can be imported to fill local supply gaps and
that other berries are considered ‘raspberry substitutes’ (Sobekova
et al. 2013). The information in this article will assist Minnesota’s
raspberry growers, industry suppliers, researchers and policy makers
interested in weighing the costs and benefits associated with spotted
wing Drosophila control.

Methods and Materials
Production Estimates
We use a combination of primary and secondary data to quantify
statewide MN raspberry production before spotted wing Drosophila
detection (ex-ante period). We chose the 2007–2009 yr to represent
the ex-ante period as they are the most recent years for which
organic raspberry data are available before detection of spotted
wing Drosophila in MN. USDA harvested acreage estimates from
the Census of Agriculture are paired with primary yield data.
Yield data for nonorganic open-field and nonorganic HT
conditions were obtained from 2008 to 2009 field trials conducted by
the University of Minnesota’s North Central Research and Outreach
Center (NCROC) in Grand Rapids, MN (USDA plant hardiness zone
3b; Agricultural Research Service, https://planthardiness.ars.usda.
gov/PHZMWeb/). We report the NCROC yield data average for five
different cultivars of fall-bearing, 3-yr-old plants. Average open-field
nonorganic yield was 4,708 pounds per acre. Average HT, nonorganic
yield was 22,253 pounds per acre over the same period (Yao and
Rosen 2011). For reference, commercial raspberry yields among the
country’s top producers, in California, Oregon, and Washington, were
18,000 pounds per acre, 5,080 pounds per acre and 6,400 pounds
per acre, respectively (USDA 2007). No distinctions are made in data
reported for the West Coast states between open-field and HT growing
conditions. Therefore we assume that the yield estimates for California,
Oregon, and Washington represent a mix of production methods.

Table 6.  MN raspberry yield loss estimates due to spotted wing Drosophila-related infestation

Spotted wing Drosophila-related yield loss
Adjusted production
20% loss
30% loss
60% loss

Organic raspberry loss (lbs)a

Nonorganic raspberry loss (lbs)b

Total raspberry loss (lbs)

6,535
1,307
1,961
3,921

1,755,904
351,181
526,771
1,053,542

1,762,439c
352,488
528,732
1,057,463

a

Represents organic red raspberries grown in open-field conditions.
Represents nonorganic red raspberries produced in open-field, black raspberries produced in open-field, and red raspberries produced in high tunnels.
c
Represents MN raspberry production in 2007 before spotted wing Drosophila was detected in the state.
b

Table 7.  Revenue losses to MN raspberry industry due to spotted wing Drosophila-related infestation

Spotted wing Drosophila-related yield lossa

Adjusted revenue
20% loss
30% loss
60% loss
a

Organic raspberry

Nonorganic

revenue loss ($)b

raspberry revenue loss($)c

Total raspberry
revenue loss ($)

11,750,460
2,350,092
3,525,138
7,050,276

11,811,301
2,362,260
3,543,390
7,086,781

60,841
12,168
18,252
36,505

Applied to 2007 ex-ante yield estimates from Table 2.
Median weighted average Midwest organic retail price in 2017 is estimated to be $9.31/lb. Source: USDA, Agricultural Marketing Service, ‘Weekly Advertised
Fruit & Vegetables Retail Prices.’ Accessed 5 February 2019.
c
Median weighted average Midwest nonorganic retail price in 2017 is estimated to be $6.70/lb. Source: USDA, Agricultural Marketing Service, ‘Weekly
Advertised Fruit & Vegetables Retail Prices.’ Accessed 5 February 2019.
b

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The USDA compiles statistics for harvested raspberry acreage in MN
every 5 yr for the Census of Agriculture; however, it does not compile
yield estimates. Consequently, the size and value of Minnesota’s
nonorganic raspberry crop is currently unknown. MN production
estimates were needed to quantify the value of spotted wing
Drosophila-related yield loss. We first estimated production in the
ex-ante period (before spotted wing Drosophila was detected) then
applied yield loss rates obtained from an electronic survey conducted
as part of this research to quantify spotted wing Drosophila losses.
Economic losses are estimated using primary survey and field
research data as well as USDA census data. We do not include the
cost of material inputs and labor associated with spotted wing
Drosophila control here. These will be addressed in a forthcoming
paper. Instead, for simplicity, we assume that there is no widespread
management in place among MN growers to effectively control the
pest and that there is no increase in the price of raspberries due to
a reduction in local supply (Bolda et  al. 2010 and Goodhue et  al.

 Journal of Integrated Pest Management, 2019, Vol. 10, No. 1

4 
Regarding organic data, raspberry acreage and yield are available for
certified organic and organic-exempt growers in Minnesota as part of
the annual USDA Organic Production Survey. Data from this secondary
source are used to quantify ex-ante organic raspberry production using
2008 data; there was no distinction made between open-field and
HT production in the survey. Therefore it is assumed that all organic
production measured comes from open-field conditions. Average certified
organic yield was 1,307 pounds per acre in 2008 (USDA 2008). Using
newly calculated nonorganic and organic production estimates, we applied
a sensitivity analysis for yield loss to determine spotted wing Drosophila
impact on seasonal raspberry production and local raspberry sales. Yield
loss estimates came from a primary survey developed for this research.

A 12-question survey was designed to better understand the economic
impact of spotted wing Drosophila on MN fruit growers during
the 2017 production year. Survey questions addressed production
practices, marketing channels, spotted wing Drosophila infestation,
spotted wing Drosophila-related yield loss, spotted wing Drosophila
control measures used and future production plans. Questions were
formatted with multiple choice single answer options, multiple
choice multi-answer options and open text write-in responses.
Before survey release, all questions were reviewed and tested for
validity with five faculty members and students representing the
Department of Applied Economics, the Department of Entomology
and the Department of Horticulture at the University of Minnesota.
The questionnaire, built and administered using Qualtrics software
(Seattle, WA), was distributed to 157 Minnesota fruit growers on 10
November 2017. Two follow-up reminders were sent electronically
on 17 and 20 November. Fruit grower contacts were supplied by the
Minnesota Department of Agriculture’s MN Grown Program. The
survey was completed by 82 individual growers (52% response rate).
Forty-five of the respondents (55%) produced raspberries in 2017.

Table 8. MN raspberry grower production intentions due to
spotted wing Drosophila infestation, 2017

n = 49
Will reduce acreage (‘probably’ or ‘definitely’)
Will not reduce acreage (‘probably’ or ‘definitely’)
Not sure

Number Percent
12
27
10

24.4
55.1
20.4

The USDA Census of Agriculture reported that 281 MN farms
grew raspberries on 296 harvested acres in 2007 (1.05 acres/farm).
Raspberries represent the second largest berry crop in Minnesota
(strawberries are number one). Using the USDA acreage data
and NCROC field-trial yield data, we estimate MN’s raspberry
production before spotted wing Drosophila detection (2007-09) at
1,393,568 pounds (4,708 lbs per acre * 296 acres). This is depicted
as ‘baseline production’ in Table 2 and assumes that all of MN’s
raspberry acreage is nonorganic, grown in open-fields using highyield red varieties and represents the total harvest (some of which
may be considered unmarketable by retailers). Next, we adjusted
for management practices (organic, HT) and cultivar differences.
The USDA Organic Production Survey suggests that five acres of
raspberries were produced on certified organic land in Minnesota
and yielded 1,307 pounds of raspberries per acre in 2008.
Total certified organic production of fresh raspberries in Minnesota
was estimated at 6,535 pounds in 2008 (Table 2).
We also know from the 2017 e-survey that while the majority of
MN raspberries were grown in open fields, approximately 8% were
grown in higher-yielding HTs (Table 3). We apply the same rate of
HT production to the ex-ante production years and estimate that
24 acres of MN raspberries reported in the Census of Agriculture
may have been cultivated under HT conditions in 2007. Utilizing
the NCROC HT yield observations for nonorganic raspberries,
22,253 pounds per acre, we quantify MN’s ex-ante HT production
at 534,072 pounds (Table 2). Write-in e-survey responses also
suggest that lower-yielding black varieties were grown in open-field
conditions on approximately 4% of raspberry acreage. We applied
these estimates to the baseline production numbers and calculated
that 13 acres of black raspberries were grown in Minnesota yielding
26,000 pounds in 2007 (Table 2). With management and varietal
adjustments applied, baseline fresh raspberry production estimates
for Minnesota were calculated at 1,762,439 pounds and defined as
‘adjusted production’ for the remainder of this report (Table 2).
Next, a sensitivity analysis is applied to aggregate raspberry
production and crop values (from Table 2) using spotted wing
Drosophila-related yield loss rates reported in the survey to estimate
the quantity and value of raspberry crop loss.
The results of the e-survey indicate that raspberry growers
have borne the highest levels of infestation among Minnesota fruit
growers surveyed. Raspberry yield losses attributed specifically to
spotted wing Drosophila infestation ranged from 2 to 100% of

Fig. 1.  Spotted wing Drosophila female (left), with serrated ovipositor highlighted; male (right), with distinctive spots on wings (C. Guedot, University of
Wisconsin-Extension).

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Survey Design and Distribution

Results and Discussion

 Journal of Integrated Pest Management, 2019, Vol. 10, No. 1 

Fig. 3.  Multiple spotted wing Drosophila larvae feeding within raspberry (S.
Wold-Burkness, University of Minnesota).

planted acreage among those surveyed with a median yield loss
of 20% in 2017 (Table 4). This occurred despite 74% of growers
actively managing to control spotted wing Drosophila. Controls
included conventional, nonorganic pesticides; organic biocontrols;
sanitation; physical exclusion and mass trapping. Median reported
MN yield losses are well below initial spotted wing Drosophilainduced raspberry yield loss estimates of 50% in California that
were observed prior to implementation of spotted wing Drosophila
management controls. Following the introduction of effective
spotted wing Drosophila chemical controls, on-farm trapping in
CA suggested that nonorganic raspberry yield losses fell from 10%
in 2011 to less than 1% during 2012. At the same time, however,
organic raspberry growers in CA experienced consistent annual yield
losses of 12% during 2011–2012 due to ineffective spotted wing
Drosophila control measures (Farnsworth et al. 2017). The relatively
high spotted wing Drosophila-related yield losses reported by MN
growers (compared to yield losses reported by CA growers) may
be explained by the later detection of spotted wing Drosophila in
Minnesota and the use of less aggressive spotted wing Drosophila
controls by MN growers.
Spotted wing Drosophila yield loss rates of 20, 30, and 60% are
assumed in the analysis. These are equal to the observed median
loss rate for organic and nonorganic survey respondents (20%), the
average loss rate for organic and nonorganic growers (30%) and
the average loss rate of growers who reported more than a 20%
loss (60%, Table 5). The median yield loss is equal to 352,488
pounds of organic and nonorganic raspberry production for 1 yr
(Table 6). We applied 2017 median retail prices for certified organic
and nonorganic raspberries, $9.31 per pound and $6.70 per pound,
respectively, to calculate the retail value of raspberry production
losses. Organic prices were compiled by USDA using 5,752 retail
price observations while nonorganic prices were compiled using
40,172 observations in 2017. A 20% yield loss would have led to
approximately $2.36 million in reduced sales for 1 yr. A 30% yield
loss, the average reported by Minnesota raspberry growers, would
have resulted in overall sales losses of $3.54 million. If we assume
a 60% yield loss, raspberry sales revenue would have declined by
over $7.09 million annually (Table 7). Given the production loss

Fig. 4.  Experimental high tunnel covered with standard poly, and fine mesh exclusion netting on each end (E.C. Burkness, University of Minnesota).

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Fig. 2.  Spotted wing Drosophila adults on raspberry with druplets damaged
by larval feeding; within hours, fruit degrades, and becomes unmarketable
(S. Wold-Burkness, University of Minnesota).

5

 6 
estimates and the economic value of calculated losses, it may come
as no surprise that some Minnesota raspberry growers planned to
reduce acreage in 2018. Approximately 24% of raspberry growers
surveyed said they would ‘probably’ or ‘definitely’ reduce acreage as
a result of spotted wing Drosophila infestation while 55% said they
‘probably’ or ‘definitely’ would not reduce acreage. The remainder of
those surveyed were undecided (Table 8).

Conclusions

Acknowledgments
We thank the Minnesota Invasive Terrestrial Plants and Pests Center, University
of Minnesota, for funding this work through the Environment and Natural
Resources Trust Fund as recommended by the Legislative-Citizen Commission
on Minnesota Resources (LCCMR), and support from the UMN Extension
IPM Program (NIFA Project 2017-70006-27278).

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Relatively little US research has been completed estimating spotted
wing Drosophila-induced yield and revenue losses for raspberries
and other soft fruits. The survey work presented here, along with the
work pioneered by Farnsworth et  al. (2017), contribute to a better
understanding of the economic impact of spotted wing Drosophila.
This article presents results from the first US grower survey on spotted
wing Drosophila infestation and yield loss. Survey results were used
to quantify raspberry production before spotted wing Drosophila
detection in Minnesota, yield loss related to spotted wing Drosophila
in 2017 and the resulting annual revenue losses for the MN raspberry
industry.
Our calculations suggest that the MN raspberry industry
produced approximately 1.76 million pounds of raspberries
annually before spotted wing Drosophila detection. Assuming a
20% reduction in yield due to spotted wing Drosophila infestation
(the median loss rate reported in 2017)  we conclude that MN
growers and retailers lost approximately $2.36 million in raspberry
sales over a 1-yr period (Table 7).
Responding swiftly to spotted wing Drosophila with effective
control measures for organic and nonorganic growers will reduce
annual losses. Combining the value of production losses (equal to $2.36
million in 2017) with the opportunity costs associated with foregone
sales in the ‘raspberry consumption capital of America’ (equal to $23.52
million in seasonal utilization in 2017, Table 1) we suggest that MN
input suppliers, growers, and retailers would benefit economically
from a significant investment in improved spotted wing Drosophila
management strategies. For example, in addition to continuing to
evaluate alternative and organic-certified insecticides for spotted wing
Drosophila control, further research is warranted to assess the use of
canopy management, alternative harvesting schedules, and/or fine-tune
the use of exclusion netting, with and without HT systems (Asplen et al.
2015, Leach et  al. 2016, Rogers et  al. 2016) (Fig. 4). Initial research
suggests that exclusion netting may be particularly valuable for raspberry
growers given the high value of the crop, but also the vulnerability
of raspberries to spotted wing Drosophila infestation in Minnesota
(Rogers et al. 2016, Holle et al. 2017). A recent economic analysis in
Italy also found that exclusion netting could be a key component of an
improved IPM program for spotted wing Drosophila, and offered high
net returns (Del Fava et al. 2017). Forthcoming research into material
and labor costs associated with spotted wing Drosophila will further
inform the discussion about how much growers are currently investing
to manage spotted wing Drosophila and the cost–benefit of additional
spotted wing Drosophila-related R&D.

Journal of Integrated Pest Management, 2019, Vol. 10, No. 1