Effects of microplastics on the physiology of living organisms on the example of laboratory reared bloodsucking mosquitoes Aedes aegypti L.

The presence of environmental microplastics (MPs) poses a significant threat to terrestrial and aquatic animals, including insects such as blood-sucking mosquitoes. The paper reports on the laboratory study of the effect of three different types of MPs, including fragmented high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS), on the viability, innate immune responses, activity of detoxifying enzymes and malondialdehyde (MDA) concentration in Aedes aegypti (Linnaeus, 1762). The results showed that dietary administration of microfragments of PP, PS and HDPE at low concentrations (4 mg/L) had no effect on the survival rate of mosquito larvae, but was observed to suppress the larval immune response. The addition of MPs to the diet resulted in a significant suppression of phenoloxidase activity compared to the control. A decrease in the activity of the detoxifying enzymes glutathione-S-transferase and non-specific esterase was observed. Dietary administration of MPs did not cause any significant change in alkaline proteolytic enzyme activity in larvae compared to the control. However, we observed a twofold increase in the activity of acid proteolytic enzymes in all experiments compared to the control (p < 0.05). MDA levels in larval homogenates remained unchanged, while lysozyme-like activity showed a slight decrease compared to the control. The observed processes may be a consequence of intestinal obstruction by MPs, which may cause microtraumas to intestinal tissues and changes in the structure and composition of the microbiota. These changes may have a profound effect on the resistance of mosquito larvae to insecticides and pathogens.