• Energy Research

ABSTRACTThe desert locust, Schistocerca gregaria, shows a strong phenotypic plasticity. It can develop, depending upon population density, into either a solitarious or gregarious phase that differs in many aspects of behaviour, physiology and morphology. Prominent amongst these differences is that solitarious locusts have proportionately longer hind femora than gregarious locusts. The hind femora contain the muscles and energy-storing cuticular structures that propel powerful jumps using a catapult-like mechanism. We show that solitarious locusts jump on average 23% faster and 27% further than gregarious locusts, and attribute this improved performance to three sources: first, a 17.5% increase in the relative volume of their hind femur, and hence muscle volume; second, a 24.3% decrease in the stiffness of the energy-storing semi-lunar processes of the distal femur; and third, a 4.5% decrease in the stiffness of the tendon of the extensor tibiae muscle. These differences mean that solitarious locusts can generate more power and store more energy in preparation for a jump than can gregarious locusts. This improved performance comes at a cost: solitarious locusts expend nearly twice the energy of gregarious locusts during a single jump and the muscular co-contraction that energises the cuticular springs takes twice as long. There is thus a trade-off between achieving maximum jump velocity in the solitarious phase against the ability to engage jumping rapidly and repeatedly in the gregarious phase.

ABSTRACTThe desert locust, Schistocerca gregaria, shows a strong phenotypic plasticity. It can develop, depending upon population density, into either a solitarious or gregarious phase that differs in many aspects of behaviour, physiology and morphology. Prominent amongst these differences is that solitarious locusts have proportionately longer hind femora than gregarious locusts. The hind femora contain the muscles and energy-storing cuticular structures that propel powerful jumps using a catapult-like mechanism. We show that solitarious locusts jump on average 23% faster and 27% further than gregarious locusts, and attribute this improved performance to three sources: first, a 17.5% increase in the relative volume of their hind femur, and hence muscle volume; second, a 24.3% decrease in the stiffness of the energy-storing semi-lunar processes of the distal femur; and third, a 4.5% decrease in the stiffness of the tendon of the extensor tibiae muscle. These differences mean that solitarious locusts can generate more power and store more energy in preparation for a jump than can gregarious locusts. This improved performance comes at a cost: solitarious locusts expend nearly twice the energy of gregarious locusts during a single jump and the muscular co-contraction that energises the cuticular springs takes twice as long. There is thus a trade-off between achieving maximum jump velocity in the solitarious phase against the ability to engage jumping rapidly and repeatedly in the gregarious phase.

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.

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.