JAPANESE JOURNAL OF ECOLOGY

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Insects as food will become an important issue in the 21st century due to population growth and global food insecurity. Most insects eaten currently by humans are terrestrial species. Some aquatic insect species are consumed in Japan, such as stoneflies, caddisflies, and dobsonflies. This study assessed the potential of aquatic insects in streams as food resources for humans using field and questionnaire surveys. Field surveys were conducted to estimate the abundance of large-bodied aquatic insects, such as dobsonfly (Protohermes grandis) and caddisfly (Stenopsyche spp.) larvae and stonefly nymphs (Perlidae). The biomass of the benthic invertebrate communities was 0.1-7.5 g/m² in dry weight, and the proportion of large-bodied insects to the total benthic invertebrates averaged 63%. The catch per unit effort (CPUE) of large-bodied aquatic insects was correlated positively with the biomass of benthic invertebrates. Considering the life histories of these insects and climate, large-bodied, edible aquatic insects could be collected efficiently from winter to early spring. Questionnaire surveys revealed a degree of distaste for the consumption of insects, or entomophagy, because of the appearance of insects. However, some people changed their negative attitude toward entomophagy after tasting cooked insects. We concluded that aquatic insects could be accepted as food items if their appearance on the plate is altered and that greater media communication and educational programs are needed to raise public awareness of the valuable roles that insects play in human life.

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Plants are adapted to use water and nutrients efficiently in environments where such resources are deficient. Typically, the way in which plants use nutrients and water for photosynthesis is illustrated using indices borrowed from economics: assimilates per nutrient used (nutrient-use efficiency, NUE) and assimilates per water lost (water-use efficiency, WUE). These are correlated with plant habitats, and ecological and physiological traits, such as foliar and wood morphology/anatomy, and can affect growth and reproduction. In nature, plants commonly face stressful environments that range from mild to severe, forming a stress gradient. Stress gradients include external factors like soil nutrients, precipitation, and altitude, but plants also face internal stress gradients through ontogeny, such as water stress arising from height growth. Therefore, plants develop various strategies to maximize resource-use efficiencies through morphological, anatomical, and physiological characteristics in response to both internal and external factors. Resource-use efficiencies are considered indices of adaptation to stressful environments. Here, we review the NUE (mainly for nitrogen and phosphorous) and WUE of plants in various ecosystems, and discuss ecological and physiological mechanisms that potentially increase these values.

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Remote sensing is an effective means of observing the spatio-temporal changes in ecosystems in the service of assessing the functions and services of such systems. Remote sensing consists of two components: the sensor and the platform. Spectral radiometers, microwave synthetic aperture radar (SAR), and laser scanners are often used to remotely sense ecosystems, whereas satellites and aircraft often serve as the platforms. Methodologies for remote-sensing ecosystem functions and services are categorized into three groups: direct mapping of individuals or communities, ecosystem mapping, and mapping of ecosystem functions and services using surrogates. In direct mapping, spatially high-resolution remote sensing, such as aircraft remote sensing, is required to accurately identify individuals. Recently, the chemical traits of individual trees in a tropical forest were delineated using an airborne hyperspectral camera and laser scanner. In terms of remote-sensing whole ecosystems, studies documenting tropical forest deforestation due to plantation development have used satellite-based optical sensors and SAR. The leaf area index and above-ground biomass of forests, derived from optical sensors and SAR, respectively, are good surrogates for the primary productivity and carbon stock of vegetation, respectively.

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