Yellow mealworms (Tenebrio molitor) are rich sources of dietary protein, fats, vitamins, fiber, moisture, and antioxidants (Kröncke and Benning, 2023, Moruzzo et al., 2021, Ravzanaadii et al., 2012, Rumpold and Schlüter, 2013, van Broekhoven et al., 2015). Given their favorable nutritional profile, mealworms are a popular sustainable feeder insect for birds, amphibians, reptiles, fish, and even human populations worldwide. Although mealworms primarily consume grains and flour, historical texts indicate that mealworms have been found in decaying wood and plant materials, which is suspected to be their natural diet (Buckland, 1981, Palm and Holz, 1959). They have also been found in bird nests and have been observed consuming the waste products of animals and other insects (Palm and Holz, 1959). Various studies have shown that the specific nutritional profile of mealworms is impacted by their diet (Kröncke and Benning, 2023, van Broekhoven et al., 2015, Bordiean et al., 2022, Noyens et al., 2023). However, it is less understood how materials found in urban environments, such as microplastics and lawn additives, affect their nutritional profile in comparison to grains or plant materials.

Urbanization results from increased human population density and the built environment with the level of urbanization varying among cities. The shift from rural to urban areas is accompanied by significant alterations to natural habitats and ecosystems that include habitat fragmentation and loss as well as pollution (Liu et al., 2016). Therefore, urban insects may be exposed to pollutants like heavy metals, pesticides, chemicals, plastics, polystyrene, and other wastes found in their environment (Adewumi et al., 2023, Sajjad et al., 2022) that could impact their nutritional composition. For example, a recent review reported that feeder insects exposed to agricultural waste accumulate pesticides as well as pharmaceuticals used to treat livestock (Malematja et al., 2023). Polystyrene is widely utilized to produce disposable packaging materials such as food containers and is known to release large quantities of microplastics, which can pollute the environment and accumulate in the soil (Sajjad et al., 2022, Wang et al., 2023). Of relevance to this study, mealworms can digest a variety of waste products including paper and Styrofoam with the help of specialized gut bacteria (He et al., 2023, Machona et al., 2022, Wang et al., 2022, Brandon et al., 2021, Yang et al., 2015). In fact, a study found that mealworms fed a diet consisting solely of Styrofoam do not exhibit signs of oxidative stress, apoptosis, or cytotoxicity (Zielińska et al., 2021).

The goal of the present study was to utilize mealworms as an emerging model organism to understand how feeding in urban substrates impacts the nutritional composition of insects. We hypothesized that mealworms consuming Styrofoam, soils, or decaying plant materials found in lawns would have a different macronutrient profile than mealworms consuming wheat germ. In addition, we predicted that mealworms consuming Styrofoam or soil treated with a weed preventative (Turf Builder) would develop oxidative stress.