Efficient Release Strategies for Aphid Natural Enemies in Flower Crops 1995 Proposal
Crops.
Aphids are a serious pest of almost every floricultural crop produced
in the United States. Current control measures for aphids depend almost
completely on the prophylactic use of insecticides, resulting in more active
ingredient applied annually for the suppression of this pest than any other
infesting floricultural crops. While this practice is understandable in
view of the explosive potential population growth within aphids, this repeated
heavy use of insecticides is clearly inconsistent with integrated pest
management, a concern for the environment, and a concern for the health
and safety of agricultural workers. The use of regular releases of commercially
available natural enemies has been demonstrated to be an effective alternative
to insecticide-based control in experimental trials.
However, the substantially higher direct cost associated with biological
control compared to conventional insecticide control has hindered its widespread
acceptance as a practical method of pest control. Several methods have
been proposed to reduce the cost of biological control; and while these
techniques have provided some economic relief, none of them have reduced
the cost structure to levels generally accepted by greenhouse growers.
The long range goal of my project is to develop effective and practical
biological pest management programs for flower crops. in this project,
I will evaluate the ability of commercially available natural enemies to
control aphid outbreaks in floricultural crops. I will also evaluate several
natural enemy release strategies based upon aphid distributions and natural
enemy behavior as a mechanism that has not been explored in sufficient
detail. The project outlined in this proposal addresses this aspect with
the anticipated benefit that it will lead to successful and cost effective
biological control of aphids. In addition, the method should be applicable
for natural enemy releases targeted at other pests of floricultural crops.
Introduction and Literature Review
The research outlined in this proposal represents a continuation of
the multi-year project originally funded by the Endowment in 1995. Because
my original proposal detailed work to be completed over a three year period,
and because I wish to stay within the limitation of 6, double- sided pages,
much of this year’s proposal is similar to my 1995 Endowment proposal with
slight modifications. These modifications include brief summaries of results
obtained to date.
Aphids (esp. the green peach aphid, Myzus persicae, and the melon aphid,
Aphis gossypii) rank as one of the most serious pests of greenhouse floricultural
crops (13,20). Difficulty in controlling this pest could be due to the
development of insecticide resistance (2) or it could be due to the development
of superior biotypes or races (22). Hence, complete reliance on chemical
control is a risky proposition. In addition, it is becoming necessary to
find aphid control strategies that are compatible with control measures
for the other key pests of ornamentals.
Under the optimal conditions of the greenhouse environment, aphid population
growth can be explosive. Aphid young are born fully formed and are able
to feed immediately. They grow rapidly, molting 4 times before they mature,
often within a week or less. Because normal sexual reproduction is not
required, eggs can start developing within an aphid when or before it is
born. By the time a female matures, several young are fully developed in
her reproductive system and are ready to be born. Young are then produced
at a rate of 3 to 6 a day for several weeks.
Aphids damage crops directly, wilting and distorting leaves and flowers
as they feed, but they also cause a number of other problems. The simple
physical presence of a large number of aphids can be a cause for concern
in flower crops grown for aesthetic purposes. The honeydew excreted by
aphids as they feed promotes the growth of black sooty molds, which in
turn reduce the crop’s photosynthesis as well as its aesthetic value. Dust,
dirt, and skins shed in molting adhere to the viscous substance, making
plants unsightly. Furthermore, aphids transmit several plant viruses.
Because most floricultural crops have little tolerance for damage, growers
must identify pest populations early and take appropriate control measures.
The need for early control has resulted in the sometimes unnecessary prophylactic
use of chemicals for aphid control in greenhouses. The repeated heavy use
of insecticides is clearly inconsistent with integrated pest management,
a concern for the environment, and a concern for the health and safety
of agricultural workers.
Inundative and augmentative biological control, or repeated releases
of large numbers of predators and parasitoids, have been proposed as possible
methods for controlling insect pests of floricultural crops (12) . This
practice is extremely effective across a variety of pest-crop systems (5,6,8).
Regardless, the 3-10 fold difference in the monetary costs typically associated
with implementing biological control compared to conventional insecticide
practices prevents most growers from embracing it as a regular practice.
As a response to this economic problem, many researchers continue to
search for natural enemies that may be more effective than their present
counterparts in hopes that a more effective natural enemy will reduce costs.
One result of this approach is an increased knowledge of many aphid natural
enemies exhibiting potential to provide control under greenhouse conditions.
These natural enemies include Aphidoletes apidimyza (the aphid midge),
Aphidius matricarie, (and other aphid parasites), Chrysoperla cornea (the
green lacewing), and Verticillium lecanii (a fungal pathogen). While this
’shotgun’ approach may eventually be successful, it has yet proven to provide
a methodology for the development of effective biological control programs
for pests of greenhouses or floricultural crops.
I propose an alternative to this perpetual search process. I propose
that at least one of the currently available natural enemies will be economical
and effective if it is optimally produced and utilized. My approach will
address (1) how mass-rearing practices may be modified to reduce producer
costs and maximize natural enemy quality which will ultimately reduce costs
to the growers, (2) how releases strategies may be modified to achieve
the best possible level of control for a specific number of natural enemies
released, and (3) how various species of natural enemies may be used in
concert to achieve biological control of an entire pest complex. Funding
for the first facet of my approach has been solicited from the Texas Higher
Education Coordinating Board, with full support from the Association of
Natural Biocontrol Producers and the USDA-APHIS Biological Control Laboratory
in Mission, TX. The third facet has received 2-years of funding from the
USDA-National Research Initiative. The generous financial support provided
by the Endowment, together with the support provided by Yoder Bros. (for
donating rooted chrysanthemum cuttings), Bunting Biological North America
(for providing parasitic wasps), and Buena Biosystems (for providing predators),
have facilitated my advances over the past year in developing efficient
release strategies to bring about aphid biological control of potted chrysanthemums.
In the studies described below, I have chosen to concentrate on C. cornea
and Aphidius colemani for several reasons. (1) C. carnea is readily available
and relatively inexpensive ($2-3 per 1,000) from numerous insectaries throughout
the US (9). (2) Biological control of green peach aphids infesting potted
chrysanthemums has been demonstrated using releases of C. cornea (15).
(3) A comparative study of several aphid parasitoids discovered that A.
colemani parasitized significantly more green peach and melon aphids than
did A. matricariae and Lysiphlebus lestaceipes (19). Based on this result,
it was concluded that A. colemani may be the most suitable species (of
the three parasitoid species) for use in aphid control.
Previous findings (15) support the need to study C. cornea biology more
thoroughly in order to develop effective biological control strategies.
Based on results from these studies, it was concluded that at least four
releases of lacewings at the rate of 1 predator to 50 aphids were needed
to provide satisfactory control (5). In addition, if there were four or
fewer aphids per plant, these were not discovered by the searching predator
and no control was achieved. It was estimated that 1st instar lacewings
search an area no more than 6 inches from the release site suggesting that
predator movement patterns, plant spacing and predator release strategies
are essential components to controlling aphid populations. In addition,
the best control was achieved on dense bushy plants (15) suggesting that
plant architecture also influences the outcome of the biological control
program.
Laboratory studies demonstrate the potential for achieving biological
control of green peach and melon aphid infesting greenhouse crops with
releases of parasitic wasps (19). In these studies, host suitability of
the melon, chrysanthemum (Macrosiphum euphorbiae), and green peach aphid
for the parasitoids A. colemani, A. matricariae, and L. testaceipes were
tested. In these tests, individual wasps were placed in petri dishes containing
thirty 2nd instar aphids for a period of 2 hours. None of the parasitoids
successfully parasitized chrysanthemum aphids. Aphidius colemani successfully
parasitized 80% of the melon aphids and 57% of the green peach aphids.
Aphidius matricariae parasitized 43% and 7% and L. testaceipes parasitized
27% and 7% of the melon and green peach aphids, respectively. I am unaware
of additional studies conducted on greenhouse floricultural crops utilizing
these three parasitoid species.
Objectives and Anticipated Benefits
The cost structure associated with natural enemy releases prohibits
widespread acceptance of this practice by greenhouse growers even though
releases of natural enemies are a feasible substitution for the use of
conventional insecticides. Several techniques have been examined to narrow
the financial gap between biological and chemical control. These techniques
include: (1) release of the minimal number of natural enemies necessary
to effect biological control (8), (2) optimization of mass-rearing programs
to minimize the cost associated with natural enemy purchases (4,16), and
(3) release of only the most effective natural enemies (7,18). A fourth
mechanism that has not been explored in as much detail is the method in
which the natural enemies are released. The project outlined in this proposal
addresses this aspect with the anticipated benefit that it will lead to
successful and cost effective biological control of aphids. In addition,
the method should be applicable for natural enemy releases targeted at
other pests of floricultural crops. I have avoided the use of banker plants
and pest-in-first strategies since these methods frequently release into
the greenhouse a pest species in addition to the target natural enemy.
These methods have not been embraced by growers attempting to produce a
crop free of insect damage.
Specific Objectives:
1. Compare rates that natural enemies locate and exploit patches of
aphids on chrysanthemums (and other potentially important floricultural
crops). In this study, the commercially available predator, C. carnea,
and the aphid parasitoid, Aphidius colemani, win first be examined, and
other natural enemies will be included as necessary. Because even small
numbers of aphids can be devastating, the speed with which natural enemies
locate aphid outbreaks is as important as how many aphids they may kill.
2. Determine how plant spacing and plant architecture influence the
ability of natural enemies to locate and kill aphids. Interplant spacing
within greenhouse benches and the distance between benches may act as barriers
across which natural enemies (especially lacewing larvae) are unable to
move. In addition, three components to plant structure; plant size or surface
area, plant parts (flowers, stems, leaves, etc.), as well as the connectivity
of the parts, are also known to influence natural enemy searching (1).
I will examine the role of plant spacings and structures on release strategies
and ability to effect biological control. With this informations periods
within a crop cycle most conducive to achieving biological control will
be identified.
3. Calculate optimum release strategy necessary for successful biological
control for a particular crop spacing and stage of the crop. Inherent within
a release of aphid natural enemies is the ability to maximize the probability
of these natural enemies locating patches of aphids within the greenhouse
in a timely manner. In theory, if the locations of aphid outbreaks within
a greenhouse are known, it may be possible to concentrate natural enemy
releases in the areas of these local pest outbreaks. Use of such a release
methodology requires the ability to accurately detect the location of each
pest outbreak and to respond quickly to these outbreaks before they increase
in size or move to other locations. Currently, the technology necessary
for this methodology is not available. However, given a basic knowledge
of the patterns associated with aphid outbreaks (21) and a basic knowledge
of how natural enemies respond to this variation, a generalized release
pattern can be generated that should minimize localized pest outbreaks
and maximize the probability of achieving successful biological control.
4. Conduct greenhouse trials to compare efficacy of each release strategy.
Tests win be conducted in greenhouses provided by commercial cooperators
(Ellison’s Greenhouses, Brenham, TX and Powell Plant Farms, Troup, TX)
to evaluate the dependence of successful biological control on the spatial
distribution and timing of natural enemy release points. Providing a useful
pest management tool to the greenhouse and floriculture industries is the
goal of this project.
Material and Methods
Objectives 1 & 2.
A low level aphid infestation will be established on chrysanthemum
plants utilizing the Myzus persicae and Aphis gossypii colonies housed
at Texas A&M. The plants will be positioned in a 600 ft2 greenhouse
section whereby a uniform or clumped distribution will be generated. Plants
completely free of any aphid infestation will also be used to generate
an environmental check treatment or distribution. One hundred wasps or
third instar lacewings will be released from a point source into the greenhouse
no later than 0800. At two-hour intervals, all infested plants and 10-20%
of the uninfested plants selected at random will be thoroughly examined
and the number of natural enemies per leaf within a plant will be recorded.
The behavior of each natural enemy, whether it is resting, foraging, or
attacking aphids will also be recorded. Examinations of plants will continue
throughout the release day until dark, at which time all infested plants
will be collected. These plants will be held in a walk-in cold-storage
room until each leaf can be examined with the aid of a dissecting microscope
for natural enemy activity. Each natural enemy species will be examined
on each host distribution three times for a total of 12 replicates. Movement
patterns and rates observed from the 2 aphid distributions will be compared
by calculating various G- statistics from a repeated goodness-of-fit test
(17) and analysis of covariance (3). The distribution of natural enemy
behaviors between treatments will also be compared by calculating the G-statistics
from a repeated goodness-of-fit test (17). Natural enemy movement rates
will be calculated using the equations outlined by Karieva (10).
Preliminary results from my research suggest that C. carnea are capable
of moving from one plant to the next even when the foliage among adjacent
plants is not touching. This result is contrary to popular belief, a belief
that has never previously be tested. Even though lacewings are able to
move from plant to plant, A. colemani are able to locate aphid outbreaks
approximately 5 times faster than C. carnea. Further, more wasps locate
aphid outbreaks than do C. carnea. The magnitude of this difference is
greater when aphid distributions are clumped (aphid outbreaks are concentrated
on a few adjacent plants) versus uniform (aphid outbreaks scattered throughout
the greenhouse). Few lacewings actually find clumped aphid distributions
and they are slow to find these aphids, possible due to their slow rate
of spread from their point of release. These preliminary results would
suggest that biological control is more likely to be successful when A.
colemani is released compared with releases of C. carnea, all else equal.
However, due to significant cost differentials between C. carnea and A.
colemani, our results also suggest that C. carnea may also provide effective
biological control if comparatively high release rates and frequent points
of release are utilized. Finally, our results indicate that biological
control can be greatly enhanced by proper adjustment of natural enemy releases
based upon a knowledge of the location of aphid outbreaks.
To determine the influence of aphid density and plant architecture on
C carnea and A. colemani searching, low, intermediate, and high aphid densities
will be created on individual plants. The number of individual plants used
in each experiment will be determined from the results obtained from the
procedures outlined in the previous paragraph. Aphid-infested chrysanthemums
will be placed in the previously described greenhouse section to generate
a clumped or uniform aphid spatial distribution. Natural enemies will be
released onto the infested chrysanthemum plants and allowed to equilibrate
their behavior to the aphid densities for half of a day. After the half-day
(morning hours), we will follow individual natural enemies for 1 hr. observation
bouts, observing their movements, the number of pests encountered, and
the number of seconds spent handling hosts. Data will be recorded in these
spatially complex and unrestricted environments with the aid of behavior
observation software (The Observer 2.0) installed in a hand-held computer.
The releases will be repeated until 30-50 individual observation bouts
have been observed for each host density on each cultivar. The mean amount
of time allocated to each behavior will be separated utilizing a 2-way
ANOVA where the species and host density are entered into the model (14).
Parasitoid movement patterns will be quantified using the equations outlined
by Kareiva & Shigesada (11).
Obiectives 3 & 4.
To test the effect of natural enemy release patterns on the outcome
of augmentative biological control, three release patterns based on (1)
the average distance dispersed per day for C. carnea and A. colemani, (2)
+1 standard deviation from the mean, and (3) -1 standard deviation from
the mean. Utilizing these three patterns, natural enemies will be released
into experimental chrysanthemum ranges of approximately 200 pots each.
The chrysanthemum ranges will be provided by cooperating growers (Ellison’s
Greenhouses, Brenham, TX & Powell Plant Farms, Troup, TX). Except for
differences in aphid management, all of the plants included in these trials
will be grown as normal chrysanthemum crops.
The effectiveness of natural enemy releases will be determined by comparing
aphid populations within exclosures (which exclude natural enemies) with
aphid populations in experimental ranges receiving natural enemy releases
(6). Each release distribution will be replicated three times for each
of the two natural enemies for a total of 12 replicates. Plants will be
inoculated with aphids as necessary to initiate a low-level aphid infestation.
Prior to initiating natural enemy releases, all of the plants within
each treatment will be visually inspected to insure similar aphid densities
and spatial distributions across replicates. Adult natural enemies will
be release weekly into each of the chrysanthemum ranges at a rate not to
exceed 1 natural enemy per plant. Using a single leaf and a single terminus
as sample units, 10 leaves and 10 termini will be sampled at random from
plants within each exclosure cage, and 30 leaves and 30 termini per week
will be sampled at random from the plants within each range outside the
cages. Sampling will commence immediately prior to the first release of
natural enemies and will conclude with crop harvest. Samples will be examined
with the aid of a dissecting microscope and the numbers of five and parasitized
aphids will be recorded. Foliage with parasitized aphids will be held in
individual Petri dishes and the emerging wasps will be identified to species.
At harvest, all leaves and termini from 40 plants selected at random from
each range will be inspected for the presence of aphids. For each plant,
the percentage of leaves infested with aphids and the numbers of aphids
per leaf will be determined.
A repeated measures ANOVA will be used to detect significant among-treatment
variations in aphid densities over sample dates. In the ANOVA model, the
treatments (open chrysanthemum ranges versus exclosure cages, the natural
enemy release patterns, and the two natural enemy species) will be defined
as main effects. Aphid densities per sample date will be weighted by the
number of termini and leaves within a sample, and leaf areas will be standardized
to the average leaf area observed over all leaf samples. Planned contrasts
among treatment means will be performed by a Scheffe test. Significant
deviation of aphid densities among the natural enemy release patterns and
the two natural enemy species will be detected using ANOVA. Percent infestation
data will be arcsin(x) transformed prior to analysis.
Literature Cited
1 Andow, DA.& D.R. Prokryn. 1990. Oecologia 82: 162-165.
2 Cross, J.V., L.R. Wardlow, R. Hall, M. Saynor, & P. Basset. 1983.
SROP/WPRS Bulletin VI/3: 181-185.
3 Edwards, A.L. 1979. Multiple Regression and the Analysis of Variance
and Covariance. W.H. Freeman and Co., San Francisco, CA.
4 Heinz, K.M. 1995. The Canadian Entomologist. Submitted
5 Heinz, K.M. & M.P. Parrella. 1990. Environmental Entomology 19:
825-835.
6 Heinz, K.M. & M.P. Parrella. 1994a. Environmental Entomology
23(5):1346-1353.
7 Heinz, K.M. & M.P. Parrella. 1994b. Biological Control 4: 305-315.
8 Heinz, K.M., L. Nunney, & M.P. Parrella. 1993. Environmental
Entomology. 22(6): 1217- 1233.
9 Hunter, C.D. 1994. Suppliers of Beneficial Organisms in North America.
CEPA, DPR, EMPM. CA.
10 Kareiva, P. 1982. Ecological Monographs 52(3): 261-282.
11 Kareiva, P.M. & N. Shigesada. 1983. Oecologia 56: 234-238.
12 Parrella, M.P., K.M. Heinz, & L. Nunney. 1992. American Entomologist
38(3): 172-179.
13 Rabasse, J.M. & I.J. Wyatt. 1985. In Biological Pest Control.
The Glasshouse Experience. Cornell University Press.
14 SAS Institute Inc. 1988. SAS/STAT User’s Guide, Release 6.03 Edition.
SAS Institute, Inc. 1028 pp.
15 Scopes, N.E.A. l969. Annals of Applied Biology 64:433-439.
16 Scopes, N.E.A. & R. Pickford. 1985. In Biological Pest Control.
The Glasshouse Experience. Cornell University Press.
17 Sokal, RR. & F.J. Rohlf, 1981. Biometry. W.H. Freeman and Co.,
San Francisco, CA.
18 van Lenteren, J.C. 1986. In Insect Parasitoids. Academic Press,
Orlando, FL.
19 van Steenis, M.J. 1993. IOBC/WPRS Bulletin 16(2): 157-160.
20 Vehrs, S. & M.P. Parrella. 1991. California Agriculture 45:
28-29.
21 Vehrs, S.L.C., G.P. Walker, & M.P. Parrella. 1992. Journal of
Economic Entomology 85(3): 799-807.
22 Wyatt, I.J. 1966. In Proceedings of the 3rd British Insecticide
and Fungicide Conference 1965. 519 pp.
Budget
Salaries and Benefits*: PI, Dr. Kevin M. Heinz** No Charge
1 graduate research assistantship (100% time) $ 20,000
1 full-time research assistant (W. Brent Merrigan at 50% time) 10,000
Supplies and Equipment: 3,000 Pots, sods, shipping of plant material,
and other miscellaneous items.
Travel: 2,000 Travel from College Station to research plots provided
by cooperating greenhouse operators in Central (Ellison’s Greenhouses)
and East (Powell Plant Farms) Texas.
Total Request***: $ 35,000
* Funding is requested for a graduate student and a technician, both
will be dedicated solely to this research on aphids infesting floricultural
crops. The graduate student win be enrolled in pest management-horticulture
curriculum at East Texas State, a member institution of the A&M system.
East Texas State University is located near Powell Plant Farms, a situation
that will reduce the costs associated with this student’s field research.
Mr. Brent Merrigan has been working with me since March 29, 1995 and
he will be retained as the technician in charge of the project. He is well-trained
and possesses the necessary talents to satisfactorily perform the detailed
work outlined in this proposal.
** The Texas Agricultural Experiment Station will contribute 10% of
Dr. Heinz’s salary and benefits in the amount of $5,967 toward this project.
*** Texas A&M University will contribute the indirect costs associated
with administering this project at the rate of 45% of the total costs,
or $15,750.
Leader Qualifications
I have been an Assistant Professor in full standing within the Entomology
Department of Texas A&M University since September 1, 1994. The focus
of my research program is to develop biological control programs for annual
cropping system. I maintain 1200 ft2 of greenhouse space and 2000 ft2 of
laboratory space with isolated insect rearing facilities to facilitate
my research on the use of predators and parasitoids to control arthropod
pests of greenhouse crops. My laboratory is well equipped to handle all
of the above studies, including four controlled environmental cabinets,
3 microscopes, four temperature recording devices from Omnidata International
Inc., a CID leaf area meter, three personal computers and printers, and
a complete video and photographic systems for documenting natural enemy
and aphid behavior. In addition, I maintain ties with the Department of
Horticulture, Texas A&M University (Dr. Don Wilkerson) and with our
extension faculty for the greenhouse industry (Dr. Bart Drees).
All of the individuals for whom I am seeking support from the Endowment
are committed to the betterment of the floriculture and greenhouse industry.
In addition to the immediate impact this research will have on the industry,
the majority of funds will be used for the education and training of students
interested in pursuing careers in floriculture. The combination of expertise,
facilities, philosophy, and aid from the Endowment guarantee that the proposed
research will contribute to the development of effective and environmentally
safe biological control programs for the floriculture industry.
Five Recent Research Publications.
Heinz, K.M. & J.M. Nelson. 1995. Interspecific interactions among
natural enemies of Bemisia in an inundative biological control program.
Biological Control. In Press.
Heinz, K.M. 1995. Predators and parasitoids as biological control agents
of Bemisia in greenhouses. In (D. Gerling & R.T. Mayer, eds.) Bemisia
1995: taxonomy, biology, damage and management In Press.
Heinz, K.M. & M.P. Parrella. 1994. Biological control of Bemisia
argentifolii (Bellows & Perrings) (Homoptera: Aleyrodidae) infesting
poinsettia (Euphorbia pulcherrima): Evaluations of releases of Encarsia
luteola Howard (Hymenoptera: Aphelinidae) and Delphastus pusillus LeConte
(Coleoptera: Coccinellidae). Environmental Entomology. 23(5): 1346-1353.
Heinz, K.M. & M.P. Parrella. 1994. Poinsettia (Euphorbia pulcherrima
Willd. ex Koltz) cultivar- mediated differences in the performance of five
natural enemies of Bemisia argentifolii (Bellows & Perring) (Homoptera:
Aleyrodidae). Biological Control. 4: 305-318.
Heinz, K.M., J.R. Brazzle, C.H. Pickett, E.T. Natwick, J.M. Nelson,
& M.P. Parrella. 1994. Delphastus pusillus as a potential biological
control agent for silverleaf whitefly. California Agriculture 48(2): 35-40.
Five Recent Grower-oriented Publications:
Heinz, K.M. 1995. Putting control in contact with your aphids. Greenhouse
Grower. Submitted.
Heinz, K.M. & M. Rose. 1995. Biological control in greenhouse crops:
New regulations are being developed that will equate beneficials with plant
pests. GrowerTalks To be published in August, 1995 issue.
Heinz, K.M. & M.P. Parrella. 1994. Bios are in Control. Greenhouse
Grower. 12(12): 32 – 39.
Heinz, K.M. 1994 Management techniques for whitefly on floricultural
crops. pp. 45-57. K.L. Robb [ed.], Proceedings of the Tenth Conference
on Insect and Disease Management, The Society of American Florists; Alexandria,
Virginia. Dallas, TX 19-21 February 1994. Ball Publishing, Batavia, EL.
Heinz, K.M., H. Munnecke, E. Lin, D. Conca, & M.P. Parrella. 1994.
New research to battle whiteflies: Does cultivar really make a difference?
GrowerTalks 57(5): 67-69.
Studentes Supervised:
1 M.A. student, 4 undergraduate projects
Papers Presented:
49 invited symposia, university lectures, and industry or scientific
conferences 28 submitted papers for scientific meetings.
