Systems approach: integrating IPM in the production system

Abstract

We have been doing a lot of research to optimize biocontrol and to convince growers that biocontrol is the way to go, but good pest control is still hit or miss because we still concentrate too much on the individual components instead of on the whole picture. Using the systems approach, I think we can build more robust IPM programs and identify areas of weakness that have to be addressed by research or innovation.

Full text

Integrated Control in Protected Crops, Temperate Climate
IOBC-WPRS Bulletin Vol. 102, 2014
pp. 37-43
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Systems approach: integrating IPM in the production system
Rose Buitenhuis
Vineland Research and Innovation Centre, 4890 Victoria Ave. N., Vineland, ON, L0R 2E0,
Canada
e-mail: Rose.Buitenhuis@vinelandresearch.com
Abstract: We have been doing a lot of research to optimize biocontrol and to convince growers that
biocontrol is the way to go, but good pest control is still hit or miss because we still concentrate too
much on the individual components instead of on the whole picture. Using the systems approach, I
think we can build more robust IPM programs and identify areas of weakness that have to be
addressed by research or innovation.
Key words: plants, environment, control agents
Introduction
Over the last decades, integrated pest management (IPM) has become the main pest control
approach in greenhouse horticulture worldwide. Many countries have taken a regulatory
approach to reduce reliance on pesticides and promote alternative approaches to pest
management (Pilkington et al., 2010). Other factors motivating adoption of IPM are the
paucity of pesticide registrations for protected agriculture in many countries, development of
pest resistance and the inherent health risks to workers and the environment. Finally,
consumer expectations are an increasingly important determining factor to reduce pesticide
residues on produce. For example, pest management practice appeared to be the second most
important factor in determining Canadian consumers’ likelihood to purchase both tomatoes
and chrysanthemums after price (Grygorczyk et al., 2014).
There are many definitions of IPM, but all involve a reduction in pesticide use through
monitoring, use of thresholds, reduced risk / selective pesticides and use of alternative pest
control methods such as biological, cultural and physical control. Almost twenty years ago,
Lewis et al. (1997) wrote: “In practice, IPM has been primarily a monitoring program in
which thresholds are established and chemicals are used only on an as-needed basis. In other
words, IPM programs have been operated with pesticide management objectives rather than
pest management objectives.” a statement that is unfortunately still true for most crops. In
principle, IPM programs include a greater role for biological control, but natural enemies are
often seen as less reliable and more expensive than the chemical alternatives (Grygorczyk,
unpublished data). One of the causes for these perceptions is that growers who are switching
(or thinking about switching) to IPM still hold a “replace pesticides with biocontrol agents”
mentality. More experienced (and successful) practitioners will tell you that you can’t directly
substitute one for the other, but that switching to biological control-based IPM involves a
paradigm shift for users and a steep learning curve.
Contrary to reactive chemical pest control, which generally has a rapid and readily
observed effect on pest numbers, biological control is best utilized in a more preventative
manner and effects are less evident in the short-term. This means that we try to predict pest
outbreaks and establish biocontrol agents before pest numbers exceed a critical threshold.

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However, biocontrol-based IPM requires more than that: if we do not understand the reason
why there are pest outbreaks, we will always face a recurrent pest problem. Fixing a situation
that is inherently flawed takes a lot of effort (and money). The paradigm shift involves a
change from reactive interventions to redesigning the components of the production
ecosystem to address underlying weaknesses that have allowed organisms to reach pest status.
This is also called the systems approach. By definition, the systems approach is a pest
management strategy where the influence of all factors affecting pest abundance is
considered, with the goal of creating a system that is inherently more robust. Pests rarely
reach damaging levels, plants are better able to tolerate feeding injury and conventional
pesticides are rarely required (Lewis et al., 1997; Bale et al., 2008). Lewis et al. (1997)
suggested three lines along which pest management approaches should be developed using
the systems approach: (i) ecosystems management, (ii) crop attributes and multitrophic
interactions and (iii) therapeutics (chemical, biological) with minimal disruption on the
system. Other authors have used a slightly different division, i.e. cultural control, host-plant
resistance and biological control (Bale et al., 2008; Skirvin, 2011).
The concepts around the systems approach were developed over 20 years ago, but has
there been much uptake? The focus in IPM research has been on making improvements to
individual components of horticultural production separately, with little regard for the impacts
that changes in the component of interest may have on the other components in the system
(Skirvin, 2011). For example, we have become very good at optimizing biocontrol agents to
make them work, but greenhouse production seems to be one of the only cropping systems
where biocontrol is successful. This is probably because greenhouse produce and flowers are
high value crops where we can afford to put in a lot of natural enemies. However, there is still
plenty of room for increasing the efficacy and cost-effectiveness of biocontrol strategies.
Systems approach in protected culture
To apply the systems approach to pest control in protected culture, I translated the systems
approach theory into three factors that need to be considered to obtain effective pest control:
the right plant, the right environment and the right control agents (Figure 1), which are
slightly different from Lewis et al. (1997), Bale et al. (2008) and Skirvin (2011). To be
successful, IPM practitioners need to build their pest management strategy on at least two,
preferably all three of these factors. Although they start out seemingly separate, these factors
are not independent. There are many interactions between the factors and changes in one
factor will affect the results of other factors in the system (symbolized by the circle in
Figure 1). All parameters within the system have to be chosen to be disadvantageous to the
pests, make the crop less susceptible/ acceptable to pests, make biocontrol agents as effective
as possible and still produce a good crop for a profit.
Much research has been done recently on individual factors and the interaction between
two factors, but a general overview of how everything fits together is missing. In the
following section, I attempted to summarize and to provide a “checklist” of elements that
should be considered within each factor in Figure 1, illustrated with some examples from
recent scientific research. Note that this is not meant to be a complete review of the scientific
literature on these subjects.

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Figure 1. Essential factors for effective pest management using a systems approach.
Plant factors
 Plant breeding for resistance
Greenhouse crops have traditionally been bred for higher yields (vegetables) or nice
appearance (ornamentals) with little regard for susceptibility to pests and diseases. Now, the
breeding industry is increasingly investing in the development of pest resistance. Results are
promising, even in ornamentals where thousands of species and cultivars are grown. For
example, chrysanthemum cultivars vary considerably in resistance to arthropod pests, and
show cross-resistance, where selection for increased resistance to one herbivore will result in
enhanced resistance to another herbivore (Kos et al., 2014), which can potentially speed up
the selection process considerably. The development of new breeding techniques, such as
marker-assisted breeding, will make selection of specific resistance traits easier, faster and
cheaper.
 Induced resistance
In addition to genetic resistance traits that are present at all times, plants also have defence
mechanisms that are induced only in response to herbivore feeding or pathogen infection.
Several beneficial soil-borne microbes or plant defense activators are known to activate these
mechanisms as well and thus prime plant defenses to help plants deal with herbivores through
mechanisms like induced systemic resistance, as well as the emission of plant volatile organic
compounds that attract beneficial insects (Pineda et al., 2010).

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 Crop management practices
High drought stress had a negative impact on aphid performance, even though the drought-
stressed plants had higher concentrations of nitrogen and amino acids. In contrast, under more
moderate levels of drought stress, aphid performance and populations may increase (Tariq et
al., 2013 and references therein). Under drought, percent parasitism of aphids was also
significantly reduced, which was probably related to reduced suitability of the aphid hosts and
reduction of volatile organic plant emissions (Tariq et al., 2013 and references therein).
Most greenhouse crops are on high-fertilizer regimes and research on greenhouse potted
gerbera and potted mini-rose suggests that nutrient solution concentrations can be reduced 50-
75% without adversely affecting the quality of the finished crop (Zheng et al., 2004; Zheng et
al., 2010). This also has the potential of making crops less susceptible to common pests such
as thrips, aphids and spider mites. Several studies have found that reducing fertilizer by 50%
can reduce pest abundance by up to 50% (Chau et al., 2005a; Chau et al., 2005b; Chau &
Heinz, 2006; Chow et al., 2009; Chow et al., 2012). Plant fertilization can affect natural
enemies as well. For example, fertilizer type altered percent parasitism by aphid parasitoids,
presumably through changes in host suitability (Pope et al., 2012 and references therein). The
potential to manipulate fertilizer or irrigation to promote negative effects on herbivorous
insects is different for each crop-pest combination. For example, in contrast to the previous
studies, sub-optimal nitrogen input (too high or too low) and drought were unfavourable to
Tuta absoluta but also unfavourable to tomato plants (Han et al., 2014).
Plant growth regulators can reduce aphid parasitism through direct toxic effects on the
parasitoid and by interfering with aphid feeding location and parasitoid foraging efficiency,
with potentially negative implications on the long-term efficacy of biological control (Prado
and Frank, 2013a; Prado and Frank, 2013b).
Environmental factors
 Physical control methods
Physical pest control includes the use of preventative strategies such as exclusion by
screening, quarantine and sanitation. Recent research in Ontario, Canada lead to the
development of biopesticide immersion treatments to control Bemisia tabaci on poinsettia
cuttings, so growers can start with a clean crop and use biocontrol agents throughout the
growing cycle (see Brownbridge et al., this issue).
During the growing season, mass trapping is a good method to lower pest numbers in a
crop. In semi-protected strawberry crops, mass trapping of Frankliniella occidentalis using
blue sticky roller traps, combined with the the F. occidentals aggregation pheromone, neryl
(S)-2-methylbutanoate, reduced adult thrips numbers per flower by 73% and fruit bronzing by
68% and was a cost-effective (Sampson and Kirk, 2013). Mass trapping of thrips is likely to
be cost-effective in other countries and other high-value crops affected by thrips, such as
cucumber and cut flowers. Alternatively, trap plants can be used for the same purpose
(Buitenhuis et al., 2007).
 Environmental conditions
An advantage of growing plants in a greenhouse is improved climate control. Temperature,
humidity, light intensity, wavelength and photoperiod can all be manipulated. Seasonal
climate conditions may affect the choice of predatory mite in greenhouse ornamentals,
especially in hot summers (Hewitt, 2013). New technologies and energy saving strategies are
leading to changed environmental conditions in greenhouses, which can also affect pests and
their natural enemies, either directly or indirectly through changes in the plant (Messelink et
al., 2014). Two reviews investigated plant mediated and direct effects of artificial lighting on
pest, natural enemies and IPM (Vänninen et al., 2010; Johansen et al., 2011). A recent new

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technology is the use of photoselective greenhouse covers that reduce aphid population
growth, but not the performance of their parasitoids (Legarrea et al., 2014).
Control agents
 Augmentative biocontrol
In crops with short production cycles, natural enemies are often not expected to establish.
High numbers are introduced and pest control is achieved mainly by the individuals that have
been released rather than their offspring. A good example is the use of Neoseiulus cucumeris
mini breeding sachets in potted flowering crops, where each pot receives a sachet which will
provision the plant with hundreds of predators over the course of several weeks (Buitenhuis et
al., 2014).
 Establishment of biocontrol ecosystem
In other crops, natural enemies are released at the beginning of the production cycle and pest
control relies on establishment of natural enemy populations throughout the growing season.
Poor establishment of natural enemies can be enhanced by providing additional resources,
such as alternative food, prey, hosts, oviposition sites or shelters (Messelink et al., 2014).
Examples are the use of ornamental pepper plants as banker plants for Orius insidiosus in
non-flowering stages of greenhouse ornamentals (Waite et al., 2014) or the addition of pollen
as supplemental food for predatory mites of thrips (Delisle et al., 2014). Designing effective
biological control programs for more than one pest species requires an understanding of all
interactions occurring among species within biocontrol communities (Messelink et al., 2012).
These include for example direct interactions between natural enemies against the same
(intra-guild predation) or different (hyperpredation) pests, and indirect interactions among
pests through the host plant or shared predators.
 Chemical control
When all of the above factors and strategies are considered there is still a role in IPM for
chemical pesticides against pests that have no alternative control agents or applied locally to
get quick suppression of pest hotspots. However, their use is more considered as backup
rather than as a primary line of defense (Lewis et al., 1997). Care must be taken to choose
chemicals that are compatible within the IPM system, with an emphasis on reduced risk
materials.
Conclusions and future research directions
The systems approach to IPM depends on strategic selection of methods, taking into account
the three main factors, right plant, right environment and right control agents, combined with
innovative approaches to enhance their effectiveness. The resulting combination should be
carefully considered for potential interactions – positive and negative – to see what delivers
the most effective and economical pest control solution. Using the systems approach, I think
we can build more robust IPM programs and identify areas of weakness that have to be
addressed by research or innovation.
Acknowledgements
Thanks to Graeme Murphy, all people at the Vineland Research and Innovation Centre,
biocontrol consultants, growers and researchers for the discussions leading up to this paper.

42
References
Bale, J. S., Van Lenteren, J. C., Bigler, F. 2008: Biological control and sustainable food
production. Philos. T. Roy. Soc. B 363: 761-776.
Buitenhuis, R., Glemser, E., Brommit, A. 2014: Practical placement improves the
performance of slow release sachets of Neoseiulus cucumeris. Biocontrol Sci. Techn. 24:
1153-1166.
Buitenhuis, R., Shipp, J. L., Jandricic, S., Murphy, G., Short, M. 2007: Effectiveness of
insecticide-treated and non-treated trap plants for the management of Frankliniella
occidentalis (Thysanoptera: Thripidae) in greenhouse ornamentals. Pest Manag. Sci. 63:
910-917.
Chau, A., Heinz, K. M. 2006: Manipulating fertilization: a management tactic against
Frankliniella occidentalis on potted chrysanthemum. Entomol. Exp. Appl. 120: 201-209.
Chau, A., Heinz, K. M., Davies, F. T. 2005a: Influences of fertilization on Aphis gossypii and
insecticide usage. J. Appl. Entomol. 129: 89-97.
Chau, A., Heinz, K. M., Davies Jr., F. T. 2005b: Influences of fertilization on population
abundance, and control of Frankliniella occidentalis on chrysanthemum. Entomol. Exp.
Appl. 117: 27-39.
Chow, A., Chau, A., Heinz, K. M. 2009: Reducing Fertilization for Cut Roses: Effect on Crop
Productivity and Twospotted Spider Mite Abundance, Distribution, and Management.
J. Econ. Entomol. 102: 1896-1907.
Chow, A., Chau, A., Heinz, K. M. 2012: Reducing fertilization: a management tactic against
western flower thrips on roses. J. Appl. Entomol. 136: 520-529.
Delisle, J., Shipp, L., Brodeur, J. 2014: Influence of supplemental food on the biology and
control efficacy of two predatory mites, Amblyseius swirskii and Neoseiulus cucumeris
(Acari: Phytoseiidae) on western flower thrips. Exp. Appl. Acarol. accepted manuscript.
Grygorczyk, A., Turecek, J., Lesschaeve, I. 2014: Consumer preferences for alternative pest
management practices used during production of an edible and a non-edible greenhouse
crop. J. Pest Sci. 87: 249-258.
Han, P., Lavoir, A. V., Le Bot, J., Amiens-Desneux, E., Desneux, N. 2014: Nitrogen and
water availability to tomato plants triggers bottom-up effects on the leafminer Tuta
absoluta. Scientific Reports 4: 4455.
Hewitt, L. 2013: Seasonal climatic variations influence efficacy of predatory mites used for
control of western flower thrips in greenhouse ornamental crops. School of
Environmental Sciences. Thesis University of Guelph, Guelph.
Johansen, N. S., Vänninen, I., Pinto, D. M., Nissinen, A. I., Shipp, L. 2011: In the light of
new greenhouse technologies: 2. Direct effects of artificial lighting on arthropods and
integrated pest management in greenhouse crops. Ann. Appl. Biol. 159: 1-27.
Kos, S. P., Klinkhamer, P. G. L., Leiss, K. A. 2014: Cross-resistance of chrysanthemum to
western flower thrips, celery leafminer, and two-spotted spider mite. Entomol. Exp.
Appl. 151: 198-208.
Legarrea, S., Velázquez, E., Aguado, P., Fereres, A., Morales, I., Rodríguez, D., Del Estal, P.,
Viñuela, E. 2014: Effects of a photoselective greenhouse cover on the performance and
host finding ability of Aphidius ervi in a lettuce crop. BioControl 59: 265-278.
Lewis, W. J., Van Lenteren, J. C., Phatak, S. C., Tumlinson III, J. H. 1997: A total system
approach to sustainable pest management. P. Natl. Aced. Sci. USA 94: 12243-12248.
Messelink, G., Bennison, J., Alomar, O., Ingegno, B., Tavella, L., Shipp, L., Palevsky, E.,
Wäckers, F. 2014: Approaches to conserving natural enemy populations in greenhouse
crops: current methods and future prospects. BioControl: 1-17.

43
Messelink, G. J., Sabelis, M. W., Janssen, A. 2012: Generalist predators, food web
complexities and biological pest control in greenhouse crops. In: Integrated pest
management and pest control – current and future tactics (eds. Larramendy, M. L. &
Soloneski, S.): 191-214. InTech.
Pilkington, L. J., Messelink, G., Van Lenteren, J. C., Le Mottee, K. 2010: "Protected
Biological Control" – Biological pest management in the greenhouse industry. Biol.
Control 52: 216-220.
Pineda, A., Zheng, S.-J., van Loon, J. J. A., Pieterse, C. M. J., Dicke, M. 2010: Helping plants
to deal with insects: the role of beneficial soil-borne microbes. Trends Plant Sci. 15:
507-514.
Pope, T., Girling, R. D., Staley, J. T., Trigodet, B., Wright, D. J., Leather, S. R., Van Emden,
H. F., Poppy, G. M. 2012: Effect of organic and conventional fertilizer treatments on host
selection by the aphid parasitoid Diaeretiella rapae. J. Appl. Entomol. 136: 445-455.
Prado, S. G., Frank, S. 2013a: Compact plants reduce biological control of Myzus persicae by
Aphidius colemani. Biol. Control 65: 184-189.
Prado, S. G., Frank, S. 2013b: Tritrophic effects of plant growth regulators in an aphid-
parasitoid system. Biol. Control 66: 72-76.
Sampson, C., Kirk, W. D. J. 2013: Can mass trapping reduce thrips damage and is it
economically viable? Management of the western flower thrips in strawberry. PLoS ONE
8: e80787.
Skirvin, D. 2011: Chasing the dream: a systems modelling approach to biological control.
Acta Hortic. 916: 129-140.
Tariq, M., Wright, D. J., Bruce, T. J. A., Staley, J. T. 2013: Drought and root herbivory
interact to alter the response of above-ground parasitoids to aphid infested plants and
associated plant volatile signals. PLoS ONE 8: e69013.
Vänninen, I., Pinto, D. M., Nissinen, A. I., Johansen, N. S., Shipp, L. 2010: In the light of
new greenhouse technologies: 1. Plant-mediated effects of artificial lighting on
arthropods and tritrophic interactions. Ann. Appl. Biol. 157: 393-414.
Waite, M. O., Scott-Dupree, C. D., Brownbridge, M., Buitenhuis, R., Murphy, G. 2014:
Evaluation of seven plant species/cultivars for their suitability as banker plants for Orius
insidiosus (Say). BioControl 59: 79-87.
Zheng, Y., Cayanan, D. F., Dixon, M. 2010: Optimum feeding nutrient solution concentration
for greenhouse potted miniature rose production in a recirculating subirrigation system.
HortScience 45: 1738-1783.
Zheng, Y., Graham, T., Richard, S., Dixon, M. 2004: Potted gerbera productrion in a
subirrigation system using low-concentration nutrient solutions. HortScience 39:
1283-1286.