Microplastics alter toxicity of the insecticide Bacillus thuringiensis israelensis to chironomid larvae in different ways depending on particle size.

Publisher: Elsevier Country of Publication: Netherlands NLM ID: 0330500 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1879-1026 (Electronic) Linking ISSN: 00489697 NLM ISO Abbreviation: Sci Total Environ Subsets: MEDLINE

Original Publication: Amsterdam, Elsevier.

Chironomidae*/drug effects ; Microplastics*/toxicity ; Larva*/drug effects ; Bacillus thuringiensis* ; Water Pollutants, Chemical*/toxicity ; Insecticides*/toxicity ; Particle Size*; Animals

Microplastics (<5 mm) are emerging freshwater contaminants that can have a wide range of effects on aquatic biota. One concern is that combined effects of microplastics (MPs) with other stressors, such as co-occurring contaminants in urban or agricultural runoff may be significant even when the direct effects of MPs may be modest. Despite the frequent detection of both insecticides and MPs in freshwater ecosystems, there is a lack of co-exposure studies of insecticides (especially Bacillus thuringiensis israelensis (Bti)) and MPs. Here we tested the effects of ingested MPs and Bti individually and in co-exposure using the aquatic midge Chironomus riparius as a model organism. First instar larvae were fed two sizes of white polyethylene particles (34-50 and 125 μm diameter) at 106 mg/L in an artificial diet and simultaneously exposed to increasing concentrations of Bti (7, 13, 27, 53, and 89 ng/L Active Ingredient) in the water column for 21 days. For comparison, a trial was also conducted with naturally occurring kaolin clay particles (1-10 μm diameter) at 106 mg/L in the artificial diet. Bti alone reduced 7-day larval survival at higher concentrations (53, and 89 ng/L). Dietary PE-MPs and kaolin did not affect the survival of C. riparius larvae. However, when exposed in combination, PE-MPs modified the toxicity of Bti. This modification was size-dependent, with smaller particles (34-50 μm) increasing survival of Bti-exposed larvae and larger particles (125 μm) reducing survival. Our results show the potential for microplastics to alter the efficacy of an insecticide widely used to control nuisance midges and mosquitoes and add to a growing body of literature describing how the toxicological effects of microplastics are influenced by the size and shape of particles.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024. Published by Elsevier B.V.)

Keywords: Bacillus thuringiensis israelensis (Bti); Chironomid; Pesticide, microplastics; Polyethylene, kaolin

0 (Microplastics)
0 (Water Pollutants, Chemical)
0 (Insecticides)

Date Created: 20241003 Date Completed: 20241115 Latest Revision: 20241116

20241116

10.1016/j.scitotenv.2024.176637

39362536