Ecotoxicological impact of Albendazole and low-density polyethylene microplastics on the collembola Folsomia candida (Willem, 1902)

Plastics offer significant benefits but also pose serious environmental concerns, especially in areas of intensive livestock production where they frequently coexist in soil with veterinary drugs such as albendazole (ABZ), a broad-spectrum anthelmintic. ABZ can enter soil ecosystems either directly through cattle excretion or indirectly via the application of contaminated manure, raising concerns about its potential harmful effects on soil health. Collembola play a vital role in soil ecosystems through organic matter decomposition and nutrient cycling and the species Folsomia candida is widely used in ecotoxicological studies due to its sensitivity to pollutants. This study examined the individual and combined effects of 28-day exposure to low-density polyethylene (LDPE) microplastics (MPs) at 0 and 0.1 w/w% (0 and 1000 mg kg- 1), alone or in combination with ABZ at 0, 0.0001, 0.1, and 1 w/w % (0, 1, 1000, and 10,000 mg kg- 1) on F. candida in a sandy soil (LUFA 2.2.). Results showed that LDPE alone had no lethal or reproductive effects on F. candida, while ABZ, either alone or with MPs, significantly reduced the insect reproduction, pointing at ABZ as the key driver of the adverse effects. Reproductive inhibition was observed even at 1 mg kg- 1, suggesting that ABZ may affect soil mesofauna at concentrations that can occur in manure-amended agricultural soils. The absence of differences in F. candida survival and reproduction suggests no synergistic effects between ABZ and MPs, nor any potential co-action mechanisms influencing ABZ behaviour under the specific experimental conditions, including soil substrate characteristics.