Linking Rangeland Management with the Nutritional Physiology and Ecology of Locusts

Rangeland management practices alter soil and plant characteristics and communities. These changes have implications for the success of pests common to grass and forage systems. Understanding how pests respond to anthropogenic influences is a key variable for the development of sustainable pest management strategies that minimize potential risk and severity of pest damage. For example, heavy livestock grazing in northeast China promotes locust outbreaks by lowering plant nitrogen content. This in turn likely decreases the amount of protein, relative to carbohydrate, that locusts receive. In this case, a low protein/high carbohydrate diet is just what this locust species needs to thrive. While many environmental factors influence locust outbreaks and plagues around the globe, understanding the interactions between livestock grazing, range quality, and locust populations is central to developing integrated control practices

Linking stoichiometric homeostasis with ecosystem structure, functioning, and stability

Ecosystem structure, functioning, and stability have been a focus of ecological and environmental sciences during the past two decades. The mechanisms underlying their relationship, however, are not well understood. Based on comprehensive studies in Inner Mongolia grassland, here we show that species-level stoichiometric homeostasis was consistently positively correlated with dominance and stability on both 2-year and 27-year temporal scales and across a 1200-km spatial transect. At the community level, stoichiometric homeostasis was also positively correlated with ecosystem function and stability in most cases. Thus, homeostatic species tend to have high and stable biomass; and ecosystems dominated by more homeostatic species have higher productivity and greater stability. By modulating organism responses to key environmental drivers, stoichiometric homeostasis appears to be a major mechanism responsible for the structure, functioning, and stability of grassland ecosystems

Efficient utilization of aerobic metabolism helps Tibetan locusts conquer hypoxia

Abstract Background Responses to hypoxia have been investigated in many species; however, comparative studies between conspecific geographical populations at different altitudes are rare, especially for invertebrates. The migratory locust, Locusta migratoria, is widely distributed around the world, including on the high-altitude Tibetan Plateau (TP) and the low-altitude North China Plain (NP). TP locusts have inhabited Tibetan Plateau for over 34,000 years and thus probably have evolved superior capacity to cope with hypoxia. Results Here we compared the hypoxic responses of TP and NP locusts from morphological, behavioral, and physiological perspectives. We found that TP locusts were more tolerant of extreme hypoxia than NP locusts. To evaluate why TP locusts respond to extreme hypoxia differently from NP locusts, we subjected them to extreme hypoxia and compared their transcriptional responses. We found that the aerobic metabolism was less affected in TP locusts than in NP locusts. RNAi disruption of PDHE1β, an entry gene from glycolysis to TCA cycle, increased the ratio of stupor in TP locusts and decreased the ATP content of TP locusts in hypoxia, confirming that aerobic metabolism is critical for TP locusts to maintain activity in hypoxia. Conclusions Our results indicate that TP and NP locusts have undergone divergence in hypoxia tolerance. These findings also indicate that insects can adapt to hypoxic pressure by modulating basic metabolic processes. </jats:sec

Merging an agent-based modelling approach of nutritional ecology and a population dynamics model at landscape level for the management of the Senegalese grasshopper

Locusts are among the most destructive agricultural pests in the world. Oedaleus senegalensis, the Senegalese grasshopper, may cause serious crop damage and food security problems throughout the Sahel region. Contrary to the protein-limitation paradigm which stipulates that low N concentration in plants impairs herbivores fitness, recent studies have shown that the Senegalese grasshopper can maximize its performance by selecting foods with high carbohydrate content relative to protein. Previous studies conducted in experimental plot fields showed that soil amendments, which decrease carbohydrate/protein content within plants had a negative impact on the pest fitness. However, the extent to which soil amendment linked with the nutrition al ecology of individuals may shape population dynamics remains unknown. This study aims at testing if we can extrapolate those results supporting a Carb-limitation hypothesis, at a landscape scale and population level of the Senegalese grasshopper. We developed an agent-based model coupling processes extracted from a population dynamics model from the 1990s with an agent-based modelling approach of nutritional ecology representing the individuals' choices of food according to their carbohydrates to protein ratio. The resulting ABM describes the lite cycle and the dynamics of Oedaleus senegalensis in a virtual landscape representing habitats and environ mental conditions in Senegal. Simulations with the model examined the effect of soil amendments on the population dynamics while considering other sources of seasonal and latitudinal variability, such as predation, climate, vegetation availability and composition. We believe that such model combining population ecology with agricultural land use practices can further provide evidence-based management strategies to support farmers in their decision-making to keep the pest below a density threshold and minimize damage

Global perspectives and transdisciplinary opportunities for locust and grasshopper pest management and research

Locusts and other migratory grasshoppers are transboundary pests. Monitoring and control, therefore, involve a complex system made up of social, ecological, and technological factors. Researchers and those involved in active management are calling for more integration between these siloed but often interrelated sectors. In this paper, we bring together 38 coauthors from six continents and 34 unique organizations, representing much of the social-ecological-technological system (SETS) related to grasshopper and locust management and research around the globe, to introduce current topics of interest and review recent advancements. Together, the paper explores the relationships, strengths, and weaknesses of the organizations responsible for the management of major locust-affected regions. The authors cover topics spanning humanities, social science, and the history of locust biological research and offer insights and approaches for the future of collaborative sustainable locust management. These perspectives will help support sustainable locust management, which still faces immense challenges such as fluctuations in funding, focus, isolated agendas, trust, communication, transparency, pesticide use, and environmental and human health standards. Arizona State University launched the Global Locust Initiative (GLI) in 2018 as a response to some of these challenges. The GLI welcomes individuals with interests in locusts and grasshoppers, transboundary pests, integrated pest management, landscape-level processes, food security, and/or cross-sectoral initiatives

How to Manage Migratory Pests and Potential Food Crises: Locusts Plagues in the 2020’s

This book is a reprint of the Special Issue How to Manage Migratory Pests and Potential Food Crises: Locusts Plagues in the 2020’s that was published in Agronomy.International audienceLocusts (Orthoptera: Acridoidea) constitute a threat to agriculture and livelihoods in many countries globally. The economic, social, and environmental consequences of these highly migratory pests are so substantial that they are treated as a national priority by many countries and several international commissions have been established to unite efforts. The start of 2020 was marked by the continued South American locust upsurge—the first major upsurge of this species in 60 years, as well as the onset of a dangerous desert locust invasion now extending from Kenya to India—the first many of these countries have seen in decades. This special issue aims to shed light on the overarching questions: What have we learned from historical outbreaks, what research is ongoing and what is needed, how serious is the current threat, and how should the world respond to plagues today? Articles in this special issue may address locust issues concerning any of the following: biotic and abiotic factors that affect population and/or behavioral dynamics including the potential role of climate change, surveys and monitoring, forecasting, management technologies, governance including the capacity of affected countries to respond, the impact of outbreaks (economic, social, and/or environmental), or related research. Specific questions authors may wish to consider include: What are the primary drivers of the current outbreaks and is climate change involved? Are recommended preventative strategies effective and what are the constraints to their application? Is there a possibility to use biological alternatives to chemical pesticides? What additional research is needed to better manage these insects? Papers addressing similar topics for other transboundary migratory pests are also welcome

Are Mycopesticides the Future of Locust Control?

International audienceLocusts are a very serious problem for agriculture and for the livelihoods of populations around the world. Many lessons have been learned from decades of controlling these pests [1]. After the intensive use of chemical insecticides, new perspectives that are more respectful of people and the environment have emerged over the last twenty years. Protozoa, such as Nosema locustae, have been used and have many benefits; however, some limitations still need to be overcome [2]. Currently, entomopathogenic fungi are the most promising alternative, at least partially, to traditional chemical insecticides. The article from Wakil et al. [3] in this Special Issue dedicated to locust management is the first field study to test the efficacy of four different entomopathogenic fungal formulations together—Metarhizium acridum (Green Muscle® and Green Guard®), Metarhizium anisopliae, and Beauveria bassiana—against nymphs and adults of the desert locust Schistocerca gregaria. The study shows that all of these formulations have the potential to control locusts under field conditions. In addition, there are sublethal effects on their reproductive ability and behavior, with reductions in diet consumption, frass production, and weight observed. The authors conclude that future research needs to explore the combination of fungus with other control agents—including chemical insecticides, microsporidia, and botanical extracts—as a means of integrated pest management of locusts in the field.Chemical pesticides have many side effects, and these have been increasingly elucidated, including their impact on human health, the environment, nontarget organisms, and biodiversity [4]. They have been shown to contribute to insect decline worldwide [5]. In addressing this issue, the use of biopesticides as a possible important component of locust management programs is a most significant recent development [6]. The benefits of using biopesticides include specificity to locusts and grasshoppers and the preservation of natural enemies [7]. The credibility of biopesticides as part of locust management programs is increasingly recognized, and programs that have included biopesticides have found them invaluable for treating locusts and grasshoppers wherever they occur [8]. As restrictions on the use of chemical pesticides rightly increase, treatment programs in the future will need to ensure their effectiveness by including biopesticides and by putting mechanisms in place to facilitate their use. Research and development supported by governments and donors will be critical in providing pathways to navigate logistical challenges such as manufacturing, storing, applications, and environmental limitations, especially the low temperature range over which locust mycopesticides are effective. It seems that we are at a turning point in locust control and that substitutes to chemical insecticides—notably mycopesticides—will become increasingly important in the future, not only in prevention—as originally thought—but also in periods of invasion, as shown by the mycopesticide-based treatments carried out during the last desert locust invasion in 2019–2020 [9,10,11]. Metarhizium anisopliae has already been listed for some years as one of the few products recommended by the Locust Pesticide Referee Group of the FAO to control the desert locust and any other locust species [12]

Are Mycopesticides the Future of Locust Control?

International audienceLocusts are a very serious problem for agriculture and for the livelihoods of populations around the world. Many lessons have been learned from decades of controlling these pests [1]. After the intensive use of chemical insecticides, new perspectives that are more respectful of people and the environment have emerged over the last twenty years. Protozoa, such as Nosema locustae, have been used and have many benefits; however, some limitations still need to be overcome [2]. Currently, entomopathogenic fungi are the most promising alternative, at least partially, to traditional chemical insecticides. The article from Wakil et al. [3] in this Special Issue dedicated to locust management is the first field study to test the efficacy of four different entomopathogenic fungal formulations together—Metarhizium acridum (Green Muscle® and Green Guard®), Metarhizium anisopliae, and Beauveria bassiana—against nymphs and adults of the desert locust Schistocerca gregaria. The study shows that all of these formulations have the potential to control locusts under field conditions. In addition, there are sublethal effects on their reproductive ability and behavior, with reductions in diet consumption, frass production, and weight observed. The authors conclude that future research needs to explore the combination of fungus with other control agents—including chemical insecticides, microsporidia, and botanical extracts—as a means of integrated pest management of locusts in the field.Chemical pesticides have many side effects, and these have been increasingly elucidated, including their impact on human health, the environment, nontarget organisms, and biodiversity [4]. They have been shown to contribute to insect decline worldwide [5]. In addressing this issue, the use of biopesticides as a possible important component of locust management programs is a most significant recent development [6]. The benefits of using biopesticides include specificity to locusts and grasshoppers and the preservation of natural enemies [7]. The credibility of biopesticides as part of locust management programs is increasingly recognized, and programs that have included biopesticides have found them invaluable for treating locusts and grasshoppers wherever they occur [8]. As restrictions on the use of chemical pesticides rightly increase, treatment programs in the future will need to ensure their effectiveness by including biopesticides and by putting mechanisms in place to facilitate their use. Research and development supported by governments and donors will be critical in providing pathways to navigate logistical challenges such as manufacturing, storing, applications, and environmental limitations, especially the low temperature range over which locust mycopesticides are effective. It seems that we are at a turning point in locust control and that substitutes to chemical insecticides—notably mycopesticides—will become increasingly important in the future, not only in prevention—as originally thought—but also in periods of invasion, as shown by the mycopesticide-based treatments carried out during the last desert locust invasion in 2019–2020 [9,10,11]. Metarhizium anisopliae has already been listed for some years as one of the few products recommended by the Locust Pesticide Referee Group of the FAO to control the desert locust and any other locust species [12]

How to Manage Migratory Pests and Potential Food Crises: Locusts Plagues in the 2020’s

This book is a reprint of the Special Issue How to Manage Migratory Pests and Potential Food Crises: Locusts Plagues in the 2020’s that was published in Agronomy.International audienceLocusts (Orthoptera: Acridoidea) constitute a threat to agriculture and livelihoods in many countries globally. The economic, social, and environmental consequences of these highly migratory pests are so substantial that they are treated as a national priority by many countries and several international commissions have been established to unite efforts. The start of 2020 was marked by the continued South American locust upsurge—the first major upsurge of this species in 60 years, as well as the onset of a dangerous desert locust invasion now extending from Kenya to India—the first many of these countries have seen in decades. This special issue aims to shed light on the overarching questions: What have we learned from historical outbreaks, what research is ongoing and what is needed, how serious is the current threat, and how should the world respond to plagues today? Articles in this special issue may address locust issues concerning any of the following: biotic and abiotic factors that affect population and/or behavioral dynamics including the potential role of climate change, surveys and monitoring, forecasting, management technologies, governance including the capacity of affected countries to respond, the impact of outbreaks (economic, social, and/or environmental), or related research. Specific questions authors may wish to consider include: What are the primary drivers of the current outbreaks and is climate change involved? Are recommended preventative strategies effective and what are the constraints to their application? Is there a possibility to use biological alternatives to chemical pesticides? What additional research is needed to better manage these insects? Papers addressing similar topics for other transboundary migratory pests are also welcome