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# Living With Locusts: Connecting Soil Nitrogen, Locust Outbreaks, Livelihoods, and Livestock Markets

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Coupled human and natural systems (CHANS) are systems of feedback linking people and ecosystems. A feature of CHANS is that this ecological feedback connects people across time and space. Failing to account for these dynamic links results in intertemporal and spatial externalities, reaping benefits in the present but imposing costs on future and distant people, such as occurs with overgrazing. Recent findings about locust–nutrient dynamics create new opportunities to address spatiodynamic ecosystem externalities and develop new sustainable strategies to understand and manage locust outbreaks. These findings in northeast China demonstrate that excessive livestock grazing promotes locust outbreaks in an unexpected way: by lowering plant nitrogen content due to soil degradation. We use these human–locust–livestock–nutrient interactions in grasslands to illustrate CHANS concepts. Such empirical discoveries provide opportunities to address externalities such as locust outbreaks, but society's ability to act may be limited by preexisting institutional arrangements.
Special Section on CHANS
http://bioscience.oxfordjournals.org June 2015 / Vol. 65 No. 6 BioScience 551
Living With Locusts: Connecting
Soil Nitrogen, Locust Outbreaks,
Livelihoods, and Livestock Markets
ARIANNE J. CEASE, JAMES J. ELSER, ELI P. FENICHEL, JOLEEN C. HADRICH, JON F. HARRISON,
AND BRIAN E. ROBINSON
Coupled human and natural systems (CHANS) are systems of feedback linking people and ecosystems. A feature of CHANS is that this ecological
feedback connects people across time and space. Failing to account for these dynamic links results in intertemporal and spatial externalities,
reaping benefits in the present but imposing costs on future and distant people, such as occurs with overgrazing. Recent findings about
locust–nutrient dynamics create new opportunities to address spatiodynamic ecosystem externalities and develop new sustainable strategies
to understand and manage locust outbreaks. These findings in northeast China demonstrate that excessive livestock grazing promotes locust
outbreaks in an unexpected way: by lowering plant nitrogen content due to soil degradation. We use these human–locust–livestock–nutrient
interactions in grasslands to illustrate CHANS concepts. Such empirical discoveries provide opportunities to address externalities such as locust
outbreaks, but society’s ability to act may be limited by preexisting institutional arrangements.
Keywords: coupled human and natural systems, sustainable agriculture, telecoupling, institutions, ecosystem externality
Locust outbreaks have affected communities for
millennia. Exodus describes the devastation of a locust
plague (Exod. 10:15 RSV): “They covered the face of the
whole land so that the land was darkened, and they ate all
the plants in the land and all the fruit of the trees which
the hail had left; not a green thing remained, neither tree
nor plant of the field, through all the land of Egypt.” Large
locust outbreaks, often called plagues, affect multicountry
regions with devastating consequences on ecology and agri-
culture. For example, during plague years, the desert locust
(Schistocerca gregaria) has adverse impacts on more than
60countries and the livelihood of one out of every 10people
on the planet (Symmons and Cressman 2001). Desert
locust plagues have been recorded since biblical times.
More recently, other locusts have increasingly inflicted
agricultural damage. For example, the Senegalese locust
(Oedaleus senegalensis) was not reported to cause economic
damage before the 1970s, but a plague in the mid-1980s
required pesticide treatment of 5 million hectares, and this
locust is now considered the main pest of the African Sahel
(Maiga etal. 2008). There are at least 20 different agricul-
turally important locust species affecting the economies
of large fractions of all continents except North America
and Antarctica, and many locusts originate in grasslands
(reviewed in Pener and Simpson 2009).
As with most ecosystems, grasslands are driven by feed-
back between human and ecological processes (Qi et al.
2012) and are a classic example of how resource degrada-
tion can come about from unmanaged and uncoordinated
use (Hardin 1968). In particular, ecological interactions
can extend human impacts through time and over space,
producing both local and far-reaching environmental and
social impacts, a process called telecoupling (Liu et al. 2013).
Research on natural resource institutions (Ostrom 1990)
and social–ecological systems (Berkes et al. 2003) has flour-
ished recently but often underplays ecosystem externalities
(Crocker and Tschirhart 1992)—the negative impacts of
human actions on other aspects of ecosystem function that,
in turn, affect people. Swarming locust outbreaks are a clear
example of a kind of ecosystem externality in which the
decisions in one location can dramatically affect the out-
comes in other—often distant—localities.
Some locusts, such as the desert locust, originate in
remote areas and only become an economic problem when
they migrate to agricultural lands. In these scenarios, there
may be minimal potential for mitigation because initial
outbreaks are dependent on factors not heavily influenced
by people. However, other locusts, such as the Senegalese
locust, originate in human-dominated (usually agricul-
tural) landscapes, where there is considerable potential for
BioScience 65: 551–558. © The Author(s) 2015. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. All rights
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doi:10.1093/biosci/biv048
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mitigative and adaptive responses. Recent research by Cease
and colleagues (2012) uncovered mechanisms showing how
degraded grasslands change the nutritional quality of vegeta-
tion in ways that promote outbreaks of the Mongolian locust
(Oedaleus asiaticus). This signals the potential for grassland
system management rules and property rights, which we
broadly refer to as institutions (North 1990), to mitigate or
exacerbate locust plagues. Here, we frame livestock grazing
systems, with locusts embedded, as a telecoupled social–eco-
logical system (figure 1) and examine the potential for man-
aging grazing systems to reduce the probability and severity
of locust outbreaks.
Livestock grazing systems, decisionmaking,
and institutions
The pressure on grasslands is growing worldwide. Grassland–
livestock systems cover 45% of the world’s land surface
(Ramankutty and Foley 1999, Reid et al. 2008), they contrib-
ute over US$1.4 trillion to the world economy (Thornton 2010), and the demand for grassland-based meat produc- tion is increasing as worldwide affluence grows (Foley et al. 2011). Therefore, grassland degradation is likely to increase in the coming decades, most notably in developing regions (Tarawali et al. 2011), where livestock and grasslands sup- port the livelihoods of over 600 million of the world’s poor (Thornton et al. 2002). Mitigating degradation requires understanding how livestock managers make decisions. Livestock managers generally choose stocking rates on the basis of grassland and socioeconomic factors, including the prices for wool, milk, or meat products. Especially in developing regions, livestock can also function as “productive assets” because they contribute to farm activities and productivity (e.g., plowing, manure), diversify “savings” portfolios (Dercon 1998), and provide a buffer against risk (Jarvis 1974). While considering these factors, farm managers can poten- tially enhance the long-run productivity and value of livestock enterprises by including information on the long- term effects of stocking decisions on the quality of their land. In addition, the long-term productivity of a region or country may be enhanced by including information on the effects of ecosystem externalities, such as the negative effects of a migrating locust swarm on crop production of neighboring lands. Figure 1. Human behavior, market forces, and ecological systems in situations in which overgrazing alters plant nutrient content, potentially producing outbreaks of agriculturally damaging locusts. at Yale University on June 2, 2015http://bioscience.oxfordjournals.org/Downloaded from Special Section on CHANS http://bioscience.oxfordjournals.org June 2015 / Vol. 65 No. 6 BioScience 553 Institutions and property-rights regimes influence the ability of communities or managers to use information about ecosystem externalities when developing grassland management strategies (McCarthy et al. 1999). Property rights are a foundational type of institution (North 1990) and are commonly classified into the following categories: individual private property, open access to a common resource, and socially optimal management (a theoretical best-case scenario in which resources are managed coopera- tively and provide the greatest net benefits to society). Let us look at these three classic regimes in turn. Private property managers generally have an incentive to consider the long-term effects of their decisions when man- aging their livestock and land holdings (Jensen and Meckling 1976). However, they have little incentive to account for spatial externalities (Smith et al. 2009) or similar ecosystem processes, such as locust outbreaks, that exceed the spatial scale of their property rights. Therefore, changing the spatial scale of management can drastically alter optimal private decisions (Hansen and Libecap 2004). Private property owners may also engage in strategic behavior, either comple- menting or free riding on neighbors’ actions (Fenichel et al. 2014). For example, if one farmer sprays locust pesticides on his own land, this may increase (in the complementing case) or decrease (in the free-riding case) the incentives for neigh- boring farmers to spray pesticides on their lands. Livestock managers will likely only voluntarily incorporate new eco- logical knowledge into their management practices if they are able to internalize the benefits from a management change. If farm managers do not capture these benefits, then institutional change (such as a change in property rights or policy) may be able to provide incentives for them to do so. Unregulated communal management seldom provides incentives for decisionmakers to proactively protect their resources (Stavins 2011). Anecdotal evidence from Inner Mongolia, China, suggests that some households with pri- vate (fenced) grazing plots choose to graze on communal grasslands and only use their own land after the common areas are severely degraded. The case of overgrazing was classically described by Hardin (1968) and has become the textbook example of the “tragedy of the commons. However, communal property regimes can have a range of welfare outcomes—from a case in which no one earns any real profit from a grazing system to the case in which live- stock managers benefit as much as a sole owner (Cheung 1970). How well a community fares depends on levels of trust and cooperation, the strength and appropriateness of rules, and, crucially for these cases, the scale at which rules are enacted and enforced (Robinson et al. 2013). Still, even communities with strong resource-management institutions do not have an incentive to incorporate effects beyond their boundaries. Finally, a socially optimal strategy could guide society to act in a cooperative fashion and internalize the benefits from acting on knowledge of ecological links. However, the trans- action costs from monitoring and enforcing such socially optimal strategies can be prohibitively costly and must be taken into account for realistic policy solutions (McCarthy et al. 1999, Libecap 2014). In any case, it seems clear that when large-scale ecosystem externalities such as locust plagues occur, the coordination of activities at a higher spatial and temporal scale by public institutions is necessary to maxi- mize social welfare. Locusts and grasshoppers and their impacts on people Some grasshoppers can become migratory locusts that link ecosystems, people, and land management decisions over long distances. Grasshoppers are key components of grassland ecosystems around the globe and play an impor- tant role in trophic dynamics and the cycling of nutrients. However, from the perspective of local livestock managers, some grasshopper species are serious pests, and outbreaks can have detrimental effects on livestock and agriculture, affecting the regional food supply. Under certain environ- mental conditions, including high grasshopper population density, some grasshopper species undergo a phenotypic shift termed phase change. In phase change, grasshoppers switch from shy and solitarious individuals to gregarious and migratory individuals that can collectively form long- distance migratory swarms. Grasshoppers that have the ability to undergo this phase change are classified as locusts (Pener and Simpson 2009). The term locust is not a taxo- nomic classification; indeed, their trait of swarming and migrating likely has evolved independently multiple times within the grasshopper family (Acrididae) because locust species appear in several subfamilies (e.g., table 1; Song 2011). There are approximately 12,000 species of grasshop- pers worldwide, but only about 20 have shown the poten- tial to transform into locusts (Pener and Simpson 2009). Although many grasshopper species can threaten agriculture on a local scale, locusts are of special concern because they can threaten agricultural production and food security over large regions. Such migratory pests impose unique interna- tional challenges, requiring coordinated multinational strat- egies for pest control (Toleubayev et al. 2007). Locust species are found on every continent outside of North America and Antarctica. North America was his- torically plagued by the Rocky Mountain locust (Melanoplus spretus), but it went extinct around 1900 (Lockwood 2004). The desert locust (S. gregaria) and the migratory locust (Locusta migratoria) are the most studied locusts because these species have broad distributions and dramatic popula- tion fluxes. The desert locust (S. gregaria) is found mostly in the Sahara Desert and other areas with low human popula- tion densities during nonoutbreak years. Although it origi- nates in natural landscapes, it can cover 20% of Earth’s land surfaces during severe plague years and cause widespread economic damage. The migratory locust (L. migratoria) is found in Africa, Europe, Asia, and Australia and has many subspecies that exhibit regional plagues (table 1). For example, the Madagascar locust plague involving Locusta at Yale University on June 2, 2015http://bioscience.oxfordjournals.org/Downloaded from Special Section on CHANS 554 BioScience June 2015 / Vol. 65 No. 6 http://bioscience.oxfordjournals.org migratoria capito began in June 2012 and continues (as of November 2014)—currently threatening the livelihoods and food security of 13 million people (see www.fao.org). The desert locust (S. gregaria) and the migratory locust (L. migratoria) have affected people for thousands of years, but other locusts have only recently emerged as agricultural threats. Locusts in the Oedaleus genus, which are found throughout Africa, Europe, Asia, and Australia, are a good example and have been particularly well studied since they became a major agricultural problem. Prior to the early 1970s, the Senegalese locust (Oedaleus senegalensis) was not reported to occur in mass numbers or cause economic dam- age, but it is now considered the main pest of the African Sahel (Maiga et al. 2008). In 1986–1987, about 5 million hectares were treated for O. senegalensis infestations (Brader 1988), whereas in a period of 7 years (1986–1992), US$177
million was spent on control (reviewed in Cheke 1990). In
Asia, the Mongolian locust (O. asiaticus) was also rarely
reported to cause agricultural damage before the 1970s, but
it is now a similarly dominant pest of grasses and crops in
northern China (Kang et al. 2007). Could the emergence of
these new threatening locust pests be the result of land-use
changes mediated by population growth and increasing
human pressure on grasslands?
Locust species are concentrated in arid grasslands (Uvarov
1957), where they compete with livestock and other grazers
for plants. For example, Australian plague locust juveniles
(Chortoicetes terminifera) form collective marching groups
and pass through pastures, consuming nearly everything in
their path (Hunter 2004). The Australian plague locust has
been a frequent agricultural pest since at least the 1870s, when
early swarms may have been promoted by the introduction
of European livestock and agriculture to Australia (Deveson
2012). During the 1984 plague, crop loss was estimated at $5 million AUD (see www.agriculture.gov.au); however, with- out locust control, an estimated$100 million AUD in crops
would have been lost. Such mechanisms of chemical control
include financial and poorly quantified
costs to human health and the environ-
ment due to pesticide use. The primary
locust control agency in Australia, the
Department of Agriculture’s Australian
Plague Locust Commission, reduces
the need for pesticide use through early
detection and intervention, targeted
spraying, and introducing biocontrol
agents such as Green Guard (a fungus,
genus Metarhizium, that targets grass-
hoppers; Hunter 2004).
In Africa and the Middle East,
(S. gregaria) plagues is orchestrated by
the United Nation’s Food and Agriculture
Organization Locust Watch. Since the
1960s, effective pesticides and concerted
monitoring and control programs have
reduced the frequency and severity of desert locust plagues
(van Huis et al. 2007). However, the monetary costs incurred
by governments and international aid agencies to control
locust plagues have been high. For example, US\$400 million
was required to control the 2003–2005 desert locust plague
cide use is accompanied by significant secondary effects on
human health and ecosystem biodiversity and may not be
conducive to long-term, sustainable intensification of agri-
cultural production in Africa (Jepson et al. 2014).
Despite control measures, locust plagues still have signifi-
cant socioeconomic impacts. Communities with persistent
vulnerabilities, such as poorer regions that have strong
dependencies on local agriculture, may be less resilient to
locust plagues (and other shocks) because households have
limited options and opportunities (Baro and Deubel 2006).
Locust plagues often exacerbate other shocks such as drought
or conflict, as was the case in the 2004–2006 Niger food crisis
(Barrett 2010). In addition to immediate impacts on food
supply, locust plagues can have far-reaching consequences.
For example, De Vreyer and colleagues (2012) studied Mali’s
1987–1989 desert locust plague’s impact on educational
outcomes. For both boys and girls born during 1987–1989
in rural locust-infested regions, there was a 25% reduction
in the proportion of children to ever enroll in school rela-
tive to urban regions. These results suggest that the financial
burden inflicted on families by the locust plague limited
funds for school fees and increased the need for children to
contribute to family incomes, further reducing school atten-
dance. Therefore, whereas locusts may have major ecological
impacts everywhere, their economic impacts are likely most
severe on poorer, agriculturally based regions.
From grasshopper to locust
The ecological conditions that promote grasshopper popu-
lation growth are diverse and vary by species. The under-
lying factors that promote explosions of swarming locust
Subfamily Species Common name Distribution
Cyrtacanthacridinae Schistocerca gregaria Desert locust Africa, Middle
East, Asia
Oedipodinae Locusta migratoria Migratory locust Broadly
throughout Africa,
Asia, Europe,
Australia, and
nearby islands
Oedipodinae Locusta migratoria capito
(subspecies)
Oedipodinae Oedaleus senegalensis Senegalese locust African Sahel
Oedipodinae Oedaleus asiaticus Mongolian locust China, Mongolia,
Russia
Oedipodinae Chortoicetes terminifera Australian plague
locust
Australia
Melanoplinae Melanoplus spretus
(extinct)
Rocky Mountain locust North America
Note: All locusts are in the grasshopper family Acrididae.
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populations are not well understood despite their social
and ecological importance (Pener and Simpson 2009). For
example, precipitation is a major abiotic factor influencing
locust and grasshopper populations; however, the effects are
complex and nonlinear and depend on life stage (Joern and
Gaines 1990).
Locusts require specific soil conditions for ovipositing
eggs in the ground: damp enough to prevent desiccation but
not wet enough to promote fungal and bacterial infections.
Rains that bring new vegetation can encourage the rapid
growth of hatchling nymphs. However, precipitation can
create cooler microclimates, potentially slowing growth and
extending intergenerational times. Locust plagues are often
the result of multiple generations of population growth,
culminating in one to several generations of sustained high
populations followed by a crash in which populations return
to low density levels (Joern and Gaines 1990).
However, precipitation is just one factor that is thought to
influence the propensity for locust outbreaks; plant quality
can also affect the growth rate, survival, and fecundity of
individual insects, thereby affecting the rate of population
increase. The specific aspects of plant quality that influence
locust growth are also complex and vary across grasshopper
species. For example, in the desert locust, S. gregaria, the
fastest growth rates occur when the insects consume equal
amounts (by mass) of protein and carbohydrate (Pener
and Simpson 2009), whereas the Mongolian locust, O. asi-
aticus, favors diets with a 1:2 protein-to-carbohydrate ratio
(Cease et al. 2012), a lower protein preference than that of
any grasshopper previously studied (Behmer 2009). Plant
quality—including the amounts and balance of protein,
carbohydrate, and other nutrients that locusts can obtain
from plants—depends greatly on soil quality and the nutri-
ents that plants can extract from soils. In turn, soil quality
is greatly influenced by land-use practices, particularly in
rangelands and agricultural ecosystems.
Research in the arid grasslands of Inner Mongolia in
northeast China illustrates the complex feedback that con-
nects livestock management to Mongolian locust outbreaks
in scenarios in which locusts originate from human-domi-
nated landscapes (Cease et al. 2012). This literature demon-
strated that excessive livestock grazing promotes Mongolian
locust outbreaks in an unexpected way: by lowering plant
nitrogen (N) content (Kang and Chen 1995, Cease et al.
2012). In this pathway, heavy grazing promotes loss of
nutrients (e.g., nitrogen) by amplifying soil erosion through
leaching and by export of manure (figure 1; Giese et al.
2013). This results in N-poor plant tissues (Chen et al.
2002). Because most N in plants is in the form of protein,
low plant nitrogen content implies protein-poor forage. In
contrast to the commonly held view that herbivores are
ubiquitously protein limited (White 1993), Cease and col-
leagues (2012) showed that the Mongolian locust preferred
and performed best on low-protein plants found in degraded
or heavily grazed pastures. Anecdotal evidence suggests
that related West African and Australian locusts have a
similar preference for low protein-to-carbohydrate ratios
in their diets. Intriguingly, agricultural reports indicate that
outbreaks of these species are common on degraded lands
(Amatobi et al. 1988, Bailey 2007, Deveson 2012). However,
the connections among land use, soil quality, plant nutrient
content, and locust plagues have yet to be investigated in
species other than the Mongolian locust.
The convergence of these patterns suggests that a com-
mon mechanism may promote locust outbreaks on degraded
lands in several parts of the world. Excessive grazing depletes
soil nitrogen, resulting in forage that is of lower quality for
livestock (an intertemporal externality) but—because low-N
plants are of higher quality for the locust—increasing the
production of migratory locusts (an ecosystem externality).
This feedback generates a spatial externality (Smith et al.
2009) that potentially induces feedback via market mecha-
nisms and governmental responses. Therefore, to under-
stand locust outbreaks, one needs to understand human
systems, locust and grassland ecology, and the connections
among them.
Telecoupling
Liu and colleagues (2013) suggested that the idea of tele-
coupling is a way of extending the concept of coupled
human and natural systems (CHANS) analysis over space
and capturing interactions across geographical locations.
A notable difference between conceptualizing grassland–
locust–livestock systems as telecoupled and previous tele-
coupling examples in the literature is the role of ecosystem
externalities (Crocker and Tschirhart 1992). Although Liu
and colleagues’ (2013) framework is flexible enough to
include ecosystem externalities, in their examples, humans
either deliberately couple geographic regions (most notably
through trade or material flows) or unintentionally couple
systems, such as through the movement of invasive spe-
cies. However, energy and materials naturally flow through
ecosystem components, such as locusts, even in the absence
of human intervention. Anthropogenic activities can create
externalities that affect these natural energy and material
flows through, say, the movement and behavior of animals,
suggesting a potentially important role for mobile organisms
as telecouplers themselves (Schmitz 2010). Such a role cre-
ates a pathway through which ecosystem externalities extend
and transfer existing conventional externalities. In such a
case, natural processes that are affected or perturbed by
humans can result in undesirable outcomes, such as reduced
ecological and economic productivity.
Externalities that arise via spatial ecosystem telecoupling
may be a common, important, and often overlooked aspect
of CHANS. The introduction of exotic, invasive species is
a good example in which the human-assisted dispersal of
organisms acts as a telecoupler but the nonhuman organisms
migrate, creating an ecosystem externality. The Mongolian
locust system shows that such ecosystem externalities can
also originate locally, in which human actions indirectly
enhance the migration and dispersal behaviors of Oedaleus
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locusts. Humans do not intentionally create the conditions
that increase the likelihood of locusts forming migratory
swarms, but when grassland users intensively compete for
resources, they have little incentive to conserve grassland
quality. As we discussed above, intensive grazing affects
nitrogen cycling and nutrient availability, which, in turn,
influences the propensity of locusts to migrate. In this case,
migration is influenced by local human decisions, but the
migration itself is what couples multiple regions. When this
happens, humans in other areas must then respond to the
locusts.
Two interconnected telecoupling paths play important
roles in the coupled human–livestock–locust–grassland
system: (1) markets, a traditional telecoupling pathway,
and (2) locust migration, a novel telecoupling pathway. The
elements of the traditional pathway can be mapped into
Lui and colleagues’ (2013) five telecoupling components:
system, flows, agents, causes, and effects. The system has
been well defined above as the grassland–locust–livestock
system. Markets, especially livestock and agricultural
markets, are telecoupling pathways that enable the flows
of information (through prices) and materials (through
global and regional trade in goods). The chief agents in the
system are the individuals (herders, agricultural vendors),
firms, and government entities that set the rules for mar-
ket interactions, such as grazing policies and agricultural
subsidies. Material flows through trade move resources
from where they are plentiful to where they are needed
(Varian 1992), and the root cause for this trade stems from
local scarcities and individuals trying to improve their
own condition. The trade of livestock and agricultural
products is an obvious—but perhaps not the most impor-
tant—way that markets couple regions. Markets also natu-
rally send price signals, which provide information about
the value and scarcity of a good in an economy, and help
regulate production (supply) and consumption (demand)
of that good. Herders and farmers adjust livestock and
agricultural production—and consumers adjust their rela-
tive consumption of meat, grain, and vegetables—on the
basis of these market signals. However, one consequence
or effect of this system is that these markets often fail to
adequately account for all the benefits and costs of these
activities, especially because ecosystems interactions seem
to play an important role.
Therefore, a novel telecoupling pathway exists in the
grassland–locust–livestock CHANS, in which human activ-
ity affects the local ecosystem and components of the ecosys-
tem (locusts) act as the telecouplers. Telecoupling through
ecosystem externalities is likely not unique to our case, but
we think it could apply to a range of CHANS contexts. In
the grassland–locust–livestock case, a resulting key empiri-
cal question is how migrating locust swarms affect local
and regional livestock and feed prices and subsequent range
management. Does locust-induced crop or range damage
increase the effective price of feed (because of decreased
supply), thereby increasing livestock prices? If so, we might
expect such a price signal to encourage the intensification of
grazing in neighboring locations (potentially causing longer-
term range degradation). Alternatively, the grassland dam-
age that results from a locust outbreak might lead herders
current herd size, resulting in a dump of livestock onto the
market. Livestock prices would then decrease, potentially
reducing vulnerability to migrating locusts. Whether such
price changes benefit livestock producers will depend on
the producer’s local situation, including the region’s level of
market integration. However, because locust risk generally
goes unpriced in the market, the ecosystem externality must
reduce overall social well-being. Recognizing the pathways
through which this feedback occurs is important for creat-
ing institutions that decrease vulnerability and help promote
welfare.
Conclusions
Ecosystem externalities and market-based information (gen-
erally via prices) link distant regions in seldom-considered
ways. The locust–grassland example we present is interesting
in itself: Locust management matters for food security for a
substantial number of people globally. However, this type of
system is not unique. The concern about the interconnec-
tions between market signaling and ecosystem externalities
telecoupling geographically distinct human and natural sys-
tems touches many of Earth’s most pressing problems. For
example, markets may send signals in a similar fashion that
influence conservation behavior with implications for biodi-
versity conservation (Horan and Shortle 1999). Ecosystem
externalities coupling geographically distinct human popu-
lations via natural ecological processes may be crucially
important for some of the most pressing emerging infec-
tious diseases, such as West Nile virus (Kilpatrick 2011) and
avian influenza (Vandegrift et al. 2010). Therefore, although
understanding the grassland–locust–livestock system can
inform solutions to pressing food security and livelihood
issues, it also provides a heuristic framework for dissecting
the pathways that connect human and ecological systems
over large spatial distances.
Acknowledgments
This research is supported by National Science Foundation
grants no. DEB-1313693 to AJC, JJE, EPF, JCH, JFH, and
BER and no. CHE-1313958 to AJC.
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Arianne J. Cease (acease@asu.edu) is an assistant professor in the School of
Sustainability at Arizona State University, in Tempe. She studies how the
dynamic interactions among plant–herbivore systems, humans, and their
environment affect the sustainability of agricultural systems. James J. Elser
(j.elser@asu.edu) is Regents’ Professor and Distinguished Sustainability
Scientist in the School of Life Sciences at Arizona State University, in Tempe.
He studies food web dynamics and biogeochemical processes using the theory
of biological stoichiometry. Eli P. Fenichel (eli.fenichel@yale.edu) is an assis-
tant professor of bioeconomics at Yale University, in New Haven, Connecticut.
He uses capital and ecological theory to build models that explicitly link eco-
logical and economic systems. This approach exposes how ecological and eco-
colostate.edu) is an assistant professor in the Department of Agricultural and
Resource Economics at Colorado State University, in Fort Collins. She studies
livestock economics with a focus on the interaction between environmental
systems and markets. Jon F. Harrison (j.harrison@asu.edu) is a professor in
the School of Life Sciences at Arizona State University. He studies the physiol-
ogy, ecology, and evolution of locusts and other insects. Brian E Robinson
(brian.e.robinson@mcgill.ca) is an assistant professor in the Department of
Geography at McGill University, in Montreal, Quebec, Canada. He studies the
relationships between natural systems and development, particularly impacts
on household livelihoods.
... A socialecological approach is a way to emphasize the interlinked social and ecological dynamics and the cross-scale and cross-level social-ecological complexity involved in managing the environment [29,30]. For example, Cease et al. [31] described the locust-grassland-human system as a coupled human and natural system, implying complex feedback that connect geographically distinct people and places across time (ecological connections with locust migration or socio-economic connections through markets). Considering locusts as a "wicked" problem [32] also induces new ways of doing science, capable of dealing with problems characterized by high stakes, uncertainties, values in dispute, and urgent decisions [33]. ...
... Diverse disciplinary approaches can be found in the social science literature on locusts: contributions can be embedded in one subdiscipline of the social sciences, such as sociology [9] or economics [25]; they can emerge from social science fields that are specifically interested in environmental issues, such as environmental history [10] or political ecology [51]; finally, they can come from interdisciplinary and transdisciplinary groups of authors who are willing to address the social variables impacting locust management [31,48]. Such papers may involve both entomologists/natural scientists alongside social scientists (interdisciplinary approach) and practitioners (transdisciplinary approach) who sometimes have a strong interest in social sciences and can even be double-hatted at the same time, being a practitioner or entomologist and trained as a social scientist. ...
... Ecologists can be pushed towards such an approach when studying the interactions between locusts and their environment, which thus includes the impact of human practices (crop farming, grazing) on the surrounding environment. For example, Cease et al. [31], Le Gall et al. [56], Word et al. [57] and others before them [58,59], demonstrated there can be a substantial impact of overgrazing or the type of crops and soil management regime on locust dynamics. This opens a space for discussion to include land management practices as a way to manage locusts, and thus to include farmers and their social environment (e.g., markets, policies) as key players. ...
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Locust outbreaks have impacted agricultural societies for millennia, they persist today, and humans aim to manage them using preventative strategies. While locusts have been a focus for natural sciences for more than a century, social sciences remain largely underrepresented. Yet, organizational, economic, and cultural variables substantially impact these management strategies. The social sciences are one important means through which researchers and practitioners can better understand these issues. This paper examines the scope and purpose of different subﬁelds of social science and explores how they can be applied to different issues faced by entomologists and practitioners to implement sustainable locust research and management. In particular, we discuss how environmental governance studies resonate with two major challenges faced by locust managers: implementing a preventative strategy over a large spatial scale and managing an intermittent outbreak dynamic characterized by periods of recession and absence of the threat. We contend that the social sciences can help facilitate locust management policies, actions and outcomes that are more legitimate, salient, robust, and effective.
... However, no studies have examined macronutrient preferences of M. sanguinipes collected directly from field populations. Understanding how an organism's nutritional requirements compare to their habitat's macronutrient composition can aid in developing management strategies based on nutrition (e.g., Cease et al. 2015, Le Gall and Tooker 2017, Word et al. 2019, Le Gall et al. 2020a. ...
... Biopesticides aside, knowing how pests respond to nutritional landscapes can open pathways for population suppression through agricultural practices. For example, for locusts and migratory grasshoppers that thrive in low nitrogen environments (Cease et al. 2012, Word et al. 2019, the nutritional landscape could be altered through soil amendments, crop rotations, or other practices that increase soil organic matter and nitrogen availability; this would, in turn, increase the plant protein: carbohydrate ratio and suppress pest populations (Cease et al. 2015, Word et al. 2019. To support the development of sustainable management options, future research should study how biopesticide challenges affect the nutritional demands of M. sanguinipes and if this species can alter its diet to decrease its susceptibility. ...
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When given a choice, most animals will self-select an optimal blend of nutrients that maximizes growth and reproduction (termed “intake target” or IT). For example, several grasshopper and locust species select a carbohydrate-biased IT, consuming up to double the amount of carbohydrate relative to protein, thereby increasing growth, survival, and migratory capacity. ITs are not static, and there is some evidence they can change through ontogeny, with activity, and in response to environmental factors. However, little research has investigated how these factors influence the relative need for different nutrients and how subsequent shifts in ITs affect the capacity of animals to acquire an optimal diet in nature. In this study, we determined the ITs of 5 th instar (final juvenile stage) Melanoplus sanguinipes (Fabricius, 1798), a prevalent crop and rangeland grasshopper pest in the United States, using two wild populations and one lab colony. We simultaneously collected host plants to determine the nutritional landscapes available to the wild populations and measured the performance of the lab colony on restricted diets. Overall, we found that the diet of the wild populations was more carbohydrate-biased than their lab counterparts, as has been found in other grasshopper species, and that their ITs closely matched their nutritional landscape. However, we also found that M. sanguinipes had the lowest performance metrics when feeding on the highest carbohydrate diets, whereas more balanced diets or protein-rich diets had higher performance metrics. This research may open avenues for studying how management strategies coincide with nutritional physiology to develop low-dose treatments specific to the nutritional landscape for the pest of interest.
... Locusts are larger grasshoppers forming swarms which can migrate to a longer distance. The desert locust Shistocerca gregaria (Forksal) and the migratory locust (Locusta migratoria Linnaeus) are studied extensively because of their wide distribution [4]. ...
... Desert locusts arising from the rural area, seem problematic when they migrate to the field crops. Their alleviation is very difficult as their emergence is not highly anthropogenic [4]. Swarms of locust can attack the field of millions of square kilometers, thereby causing substantial loss in agricultural, social, economic and environmental aspects [16]. ...
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Desert locusts are the harmful pests that feed on every edible substance available on their way. One single mature locust can consume crops equal to its weight. In present condition where various world nations are struggling with the problem of food scarcity, this desert locust invasion has emerged as a considerable setback in achieving the universal goal of food security. Frequent outbreaks have led to tremendous environmental and economic losses. So, different control strategies are introduced in local as well as international level to deal with this dreadful issue. Desert locusts were observed in 55 districts of Nepal causing minimal crop damage compared to the past crop losses in Nepal in 2020. However, for the efficient way of mitigation of desert locust, farmers in developing nation like Nepal have to heavily rely on fast-acting chemicals that deliver rapid results but fail to maintain environmental integrity. A technical taskforce was formed in 26th May 2020, a month before the entry of desert locust in Nepal from India to prevent the possible crop loss. The government of Lumbini Province, Nepal had declared to buy locusts at Rs. 20 per kg so as to encourage the people for their collection. Approaches based on IPM (Integrated Pest Management) that emphasize on effective incorporation of chemical and biological insecticides with prediction and monitoring technologies have been prompted against desert locust. Recent experimental studies and researches are prioritizing on discovering potential solutions through financial coordination from governmental and non-governmental bodies. After reviewing articles from various journals, magazines and proceedings, the authors have highlighted the loss in the agricultural sector due to desert locust attack along with its advanced control and management options. The control and mitigation strategies mentioned in this article would be a useful resource for farmers as well as researchers on assessing this problem
... Locust outbreaks have occurred in many regions, lead to unpredictable agricultural outputs, and threaten human wellbeing (Cease et al., 2015;Zhang et al., 2019). The Tibetan Plateau, the highest area in the world, extending over 2.5 million km 2 , has suffered severe locusts damage (Cao et al., 2004). ...
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Plants have evolved various defense mechanisms to cope with biotic and abiotic stresses. Cooperation with microorganisms, especially arbuscular mycorrhizal fungi (AMF), strengthens the defense capabilities of host plants. To explore the effect of AMF on the growth of Elymus and the defenses against locust feeding, we designed a two-compartment device to connect or cut the mycelia and roots. We used this to investigate communication cues and pathways between donor and receiver plants. We found that AMF significantly increased the nitrogen content and decreased the carbon to nitrogen (C:N) ratio of donor plants and receiver plants and the carbon content of both. After the establishment of the common mycorrhizal network (CMN) with AMF between the two chambers, inoculations of donor plants challenged by locusts caused enhancement in four defense-related enzymes, namely, lipoxygenase, polyphenol oxidase, phenylalanine ammonia lyase, and β-1,3-glucanase, in the receiver plants. The main components of volatile organic compounds emitted by receiver plants were terpenoids. The findings indicated that AMF could not only improve plant growth but also activate the defense response of plants to insect feeding. Four defense enzymes, volatile organic compounds, and carbon and nitrogen content were involved in the defense response, and the mycelial network could act as a conduit to deliver communication signals.
... Land use is influenced by the abundance and distribution of grasshoppers, especially Oedaleus senegalensis, likely through soil-plant interactions. The O. senegalensis abundance was negatively correlated with plant Nitrogen (Word et al. 2019) because this species prefers low Nitrogen environments (Cease et al. 2015). Second, increasing crop diversity through a mixed planting system. ...
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Leksono AS, Yanuwiadi B, Khotimah A, Zairina A. 2021. Grasshopper diversity in several agricultural areas and savannas in Dompu, Sumbawa Island, Indonesia. Biodiversitas 23: 75-80. In Sumbawa Island, the conversion of forests and savannahs into agricultural land has increased rapidly since 2010. This research aims to compare grasshopper species' abundance, richness, and diversity between several farmland and savannas in Dompu, Sumbawa Island. It was conducted at ten locations in Dompu, Sumbawa Island, and included an ecotone, two post-harvested rice farms, two post-harvested corn farms, a mixed farm, a vegetable farm, and three savannas. Furthermore, samples were taken four times from four plots at each location in the post-harvest period from August to September 2021. Grasshopper sampling was carried out using the sweeping method with an insect net with each plot size of 2 x 10 m2. A total of 2264 individual grasshoppers belonging to 30 species and four families were collected from all research sites. The dominant species were Alloteratura sp., Trilophidia annulata, Atractomorpha crenulata, Phlaeoba fumosa, Oxya japonica and, Phlaeoba infumata. The greatest grasshopper species richness and diversity were found in post-harvest rice farms, while the lowest was in the vegetable farm, and most of these species are considered pests. This research shows that the composition of grasshoppers on agricultural land is very similar to that of the adjacent savannah. Hence, monitoring and controlling their presence is necessary by paying attention to savannas as refuge land.
... To remedy this problem of locusts outbreak, we have designed smart agriculture and locust prevention system that will monitor agricultural factors such as soil moisture, temperature, and humidity using sensors in real-time. Locusts habitats are closely related to different agricultural factors [5], so we firmly believe that this work will help the farmers to supervise their land from the possible outbreak of locusts. Our proposed system will be able to alert the farmers so that they can take precautions against any possible outbreak. ...
Conference Paper
Full-text available
Locust and grasshopper infestation have a long history of affecting crops and human lives. From ancient Egypt to the Bronze age, everywhere, we have seen the manifestation of locust outbreaks and how humans have fought against it for their survival generations after generations. The latest locust eruption began in June 2019 and has continued through 2020. It has been the worst one in the last 70 years in Middle Africa, Middle East, South Asia, and South America. Countries are taking precautions to be safe from this outbreak because, after this corona pandemic, no nation is willing to face another economic pandemic. In advances of facing the consequences of the locust swarms, we need to find an effective and smart solution. In this paper, we have come up with the idea of monitoring important agricultural factors such as soil moisture, temperature, and humidity using sensors to provide real-time information to the farmers about imminent locust infestation to their mobile. Also, to ease their work, our proposed system will provide water and pesticides automatically to the fields by using Raspberry Pi and Node MCU. Our proposed system will generate ultraviolet light and loud noise to kill the insects in case of a locust outbreak. As locust's habitats are closely related to different agricultural factors, linear regression, logistic regression, and support vector regression, machine learning algorithms have been implemented to predict the temperature and humidity so that the farmers can anticipate these factors well ahead of time and plan accordingly. Overall a next-generation solution to fight the locusts has been implemented in this paper.
... It is evident from the previous studies that human activities can alter the locust population dynamics just by managing the land (Cease et al. 2015). Heavy livestock grazing Desert Locust Schistocerca gregaria Forskål (Acrididae): Biology, Management and Strategies: A Review practices in the region of Mongolia results in low plant nitrogen content thus makes the ecosystem more susceptible to Mongolian locust (Oedaleus asiaticus) outbreak (Cease 2012). ...
Article
Full-text available
Early 2020 witnessed the emergence of global agrarian crisis with the widespread burgeoning of the destructive migratory pest, Desert Locust (Schistocerca gregaria) in East Africa, South-west Asia, Pakistan and India. Characterized by the ability to eat ravenously, breed exponentially and migrate rapidly; locust swarms has led to substantial agrarian disaster. The current official strategy is to control the upsurges to evade plague. Though the strategy may seem attractive and efficient, it is sensible only if the numbers are relatively low. The socio-economic and environmental challenges posed by the unprecedented locust outbreak has prompted the scientists worldwide to emanate an effective preventive management strategy based on updated knowledge of pest biology, ecology and behaviour along with efficient monitoring, data management, analysis, forecasting, resource deployment and control techniques. Additionally, the integrated network of field teams, decision makers, analysts, rural governing bodies and farmers could potentially offer better compliance to the pest management strategies.
... However, a change in environmental conditions and growth in population may initiate the gregarious phase, which can lead to an outbreak [4]. Furthermore, locust population dynamics are also influenced by land management [7]. For locust phase polyphenism and population density research, we refer the reader to [8][9][10][11]. ...
Article
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Locust outbreaks around the world regularly affect vast areas and millions of people. Mapping and monitoring locust habitats, as well as prediction of locust outbreaks is essential to minimize the damage on crops and pasture. In this context, remote sensing has become one of the most important data sources for effective locust management. This review paper summarizes remote sensing-based studies for locust management and research over the past four decades and reveals progress made and gaps for further research. We quantify which locust species, regions of interest, sensor data and variables were mainly used and which thematic foci were of interest. Our review shows that most studies were conducted for the desert locust, the migratory locust and Australian plague locust and corresponding areas of interest. Remote sensing studies for other destructive locust species are rather rare. Most studies utilized data from optical sensors to derive NDVI and land cover for mapping and monitoring the locust habitats. Furthermore, temperature, precipitation and soil moisture are derived from thermal infrared, passive and active radar sensors. Applications of the European Sentinel fleet, entire Landsat archive or very-high-spatial-resolution data are rare. Implementing new methods (e.g., data fusion) and additional data sources could provide new insights for locust research and management.
Chapter
Insect populations can fluctuate dramatically in short periods of time, because of their short generation time and rapid reproductive rates. Population fluctuations vary in amplitude and frequency. Stable populations fluctuate little and attract little attention. Irruptive populations can fluctuate by orders of magnitude and threaten human resources. Cyclic populations fluctuate at relatively regular intervals. The factors that control these fluctuations have generated considerable scientific and public interest, both for understanding population dynamics and for managing insect populations. Fluctuations are controlled by both abiotic and biotic factors. Abiotic factors act in a density-independent manner. Exposed insects are affected without respect to their density. Biotic factors, especially competition and predation, act in a density-dependent manner. The effect of these factors increases with population density, thereby slowing and ultimately reversing population growth. Population irruptions are favored by concentration of suitable resources over wide areas, as in agricultural and silvicultural systems. Climate change is expected to exacerbate insect outbreaks.
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