Migration allows animals to track favorable environments and avoid harmful conditions but is energetically costly. There are different types of migration, such as tidal/daily, seasonal, and lifetime. Locust migratory swarms are one such famous phenomena that can have dramatic effects on human livelihoods. During long-distance flight, locusts rely on lipid oxidation from fat stores, while initial flight is fueled by carbohydrates. However, limited studies have tested how dietary macronutrients affect insect flight performance. Therefore, we asked: How do different dietary macronutrient ratios affect prolonged flight migration? We predicted that high carbohydrate diets would lead to high body lipid synthesis which would increase flight performance. We reared locusts in three crowded cages from 5th instar to adulthood on artificial diet varying in p:c ratio, supplemented with lettuce and water tubes, ad libitum. We used 7-14-day old adult males for flight performance assays where each day we used new individuals for tethered flight for 12 h in wind tunnels (~12 km·h-1) and video recorded their flight. We found that locust flight duration and quality increased with a decrease of dietary p:c ratio. Using control groups of locusts, we estimated that across 1 day of flight (up to 12 h), locusts lost on average in all treatments ~25 or ~30% of their total body lipid content. We concluded that long distance flight is improved by a high carbohydrate and low protein diet for L. migratoria by increasing their fuel sources. This work was supported by NSF # 1942054.

Studies in both terrestrial and aquatic ecosystems have documented the potential importance of consumers on ecosystem-level nutrient dynamics. This is especially true when aggregations of organisms create biogeochemical hotspots through nutrient consumption, assimilation, and remineralization via excretion and egestion. Here, we focused on aggregations of humans in cities to examine how diet and waste management interact to drive nitrogen- (N) and phosphorus- (P) fluxes into nutrient pollution, inert forms, and nutrient recycling. We constructed six diet patterns (five US-based and one developing nation) to examine N- and P-consumption and excretion, and explored their implications for human health. Next, we constructed six waste-management patterns (three US and three for developing nations) to model how decisions at household and city scales determine the eventual fates of N and P. When compared to the US Recommended Daily Intake, all US diet patterns exceeded N and P requirements. Other than the “enriched CO₂ environment scenario” diet, the typical US omnivore had the greatest excess (37% N and 62% P). Notably, P from food additives could account for all of the excess P found in US omnivore and vegetarian diets. Across all waste-management approaches, a greater proportion of P was stored or recycled (0 to > 100% more P than N) and a greater proportion of N was released as effluent (20 to > 100% more N than P) resulting in pollution enriched with N and a recycling stream enriched with P. In developing nations, 60% of N and 50% of P from excreta entered the environment as pollution because of a lack of sanitation infrastructure. Our study demonstrates a novel addition to modeling sustainable scenarios for urban N- and P-budgets by linking human diets and waste management through socio-ecological systems.

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.