Elemental concentrations in the frass of saproxylic insects suggest a role in micronutrient cycling

Multi-Elemental Analysis of Edible Insects, Scorpions, and Tarantulas from French (Online) Market and Human Health Risk Assessment Due to Their Consumption: A Pilot Study

Edible insects are becoming increasingly popular as protein alternatives to traditional animal-based products. As such, information on their elemental composition is important to ensure they are safe for human consumption. This article describes the development and validation of a rapid, reliable method for the simultaneous determination of 19 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Pb, Se, Sr, and Zn) in edible insects by inductively coupled plasma mass spectrometry (ICP-MS) following closed vessel microwave digestion. The method was validated using three insect certified reference materials, namely black soldier fly larvae meal (BFLY-1), cricket flour (KRIK-1), and mealworm powder (VORM-1). The method was applied to analyze twelve different (whole) insect species. The maximum amount of each sample was calculated for As, Cd, and Pb with respect to their provisional tolerable daily intake values established by the Food and Agricultural Organization/World Health Organization. Most of the samples, except for scorpions and tarantulas, were safe to consume at large doses (1000-10,000 insects per day). Furthermore, most of the samples contained high levels of Fe, K, Na, and Zn, providing a preliminary overview of the nutritional profile of these novel protein alternatives.

The contribution of photodegradation to litter decomposition in a temperate forest gap and understorey

Litter decomposition determines carbon (C) backflow to the atmosphere and ecosystem nutrient cycling. Although sunlight provides the indispensable energy for terrestrial biogeochemical processes, the role of photodegradation in decomposition has been relatively neglected in productive mesic ecosystems. To quantify the effects of this variation, we conducted a factorial experiment in the understorey of a temperate deciduous forest and an adjacent gap, using spectral-attenuation-filter treatments. Exposure to the full spectrum of sunlight increased decay rates by nearly 120% and the effect of blue light contributed 75% of this increase. Scaled-up to the whole forest ecosystem, this translates to 13% loss of leaf-litter C through photodegradation over the year of our study for a scenario of 20% gap. Irrespective of the spectral composition, herbaceous and shrub litter lost mass faster than tree litter, with photodegradation contributing the most to surface litter decomposition in forest canopy gaps. Across species, the initial litter lignin and polyphenolic contents predicted photodegradation by blue light and ultraviolet B (UV-B) radiation, respectively. We concluded that photodegradation, modulated by litter quality, is an important driver of decomposition, not just in arid areas, but also in mesic ecosystems such as temperate deciduous forests following gap opening.