Abstract
Vertebrates obtain the prohormone vitamin D primarily by endogenous cutaneous synthesis under ultraviolet b (UVb) exposure. To date, endogenous synthesis of vitamin D in insects has never been investigated. In an initial experiment, we exposed four insect species which differ in ecology and morphology (migratory locusts, house crickets, yellow mealworms and black soldier fly larvae (BSFL)) to a low irradiance UVb source. In a second experiment we exposed these species to a higher UV irradiance, and in a third we tested the effect of exposure duration on vitamin D concentrations in yellow mealworms. Low irradiance UVb tended to increase vitamin D3 levels in house crickets, vitamin D2 levels in BSFL and vitamin D2 and D3 in yellow mealworms. Higher UVb irradiance increased vitamin D3 levels in all species but BSFL. Both BSFL and migratory locusts had increased vitamin D2 levels. Longer UVb exposure of yellow mealworms increased vitamin D2 and increased vitamin D3 until a plateau was reached at 6400 IU/kg. This study shows that insects can synthesize vitamin D de novo and that the amounts depend on UVb irradiance and exposure duration.
Highlights
Vitamin D metabolites perform a hormonal function in a wide variety of animal species[1,2,3]
We conducted three experiments in which we investigated: 1) whether insect species, differing in phylogeny and ecology have the capacity to synthesize vitamin D when exposed to ultraviolet b (UVb), 2) whether exposure
The complete chicken feed provided to the house crickets and black soldier fly larvae (BSFL) in the first experiment had a high concentration of vitamin D3 (12,000 IU/kg DM)
Summary
Vitamin D metabolites perform a hormonal function in a wide variety of animal species[1,2,3]. Most commercially produced insects have far lower vitamin D concentrations[9,24,25,26] As these are normally not exposed to sunlight or other sources of UVb radiation, they likely obtain their vitamin D solely via the diet. Whether insects are capable of de novo synthesis is hitherto unknown This animal class is highly diverse and contains species with large differences in their morphology and ecology, including their degree of exposure to solar radiation. These aspects could affect their vitamin D synthesizing capacity and their vitamin D content. Diet ingredients Carrot (Daucus carota) Ryegrass (Lolium perenne) Wheat bran Mealworm feed (experiment 1) Mealworm feed (experiment 2) Chicken feed (experiment 1) Cricket feed (experiment 2) Migratory locusts House crickets Yellow mealworms Black soldier fly larvae to a higher UVb irradiance leads to a higher vitamin D concentration, and 3) how the duration of UVb exposure affects the vitamin D concentration
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