Examining effects of ontogenic microplastic transference on Culex mosquito mortality and adult weight

Abstract

Microplastics (MPs) continue to proliferate and pollute aquatic and terrestrial environments globally. The impacts of MP pollution on ecosystems and their functioning remain poorly quantified, with most research hitherto focusing on marine ecosystems. There is a paucity of information on the impacts of MPs in freshwater ecosystems, despite the broad range of pathways through which MPs can proliferate and the extensive range of species which actively ingest MPs in these systems. Of particular interest are organisms that bridge aquatic and terrestrial habitats. The present study thus examines the uptake, ontogenic transference and effect of different concentrations (0, 50, 100 and 200 MPs mL-1) and sizes (2 and 15 µm) of polystyrene MPs between aquatic and terrestrial life stages of Culex pipiens complex mosquitoes. Both 2 and 15 µm MPs transferred from the aquatic larval to terrestrial adult stage of Culex mosquitoes, and uptake correlated tightly with initial exposure concentration. However, neither concentration nor size of MPs significantly influenced mortality rates between the aquatic larval and terrestrial adult stage. There was also no impact of MPs on the weight of emerging mosquito adults. We thus demonstrate that MPs can be transferred ontogenically through organisms with complex life histories, presenting a potential pathway for dispersal of MPs into terrestrial environments. We also show that MPs exposure does not affect mortality rates between life stages of freshwater Culex populations. This suggests that MPs do not impact nutritional uptakes, with unhampered development to adulthood facilitating subsequent dispersal of MPs aerially and between freshwater and terrestrial habitats.

The influence of microplastics on trophic interaction strengths and oviposition preferences of dipterans

“…Microplastics continue to proliferate across the biosphere, with ecological implications frequently unknown (Carlos de Sá et al, 2018;Mason et al, 2018;Sighicelli et al, 2018;Wagner and Lambert, 2018). In the present study, we further demonstrate active uptake of MPs through filtering by larval mosquitoes (Al-Jaibachi et al, 2018a, 2018b. Furthermore, we demonstrate that MPs can be transferred and retained trophically from filter feeding organisms to higher predators, and that trophic transference relates to consumption rates.…”

“…It is probable that colonists are naïve to potential risks of MPs to fitness. However, Al-Jaibachi et al (2018a) found that MPs have little influence on the survival and fitness of Culex mosquitoes across their life history. Whilst this is the first study to quantitatively link MP transfer with predation rates, work is required to further explore potential trophic accumulation of MPs, alongside behavioural implications, and to discern the potential for aerial dispersal of MPs by freshwater insects aside from mosquitoes (Al-Jaibachi et al, 2018b).…”

“…Larval Culex mosquitoes actively filter and retain MP particles, and MPs have been shown to transfer ontogenically from larval to pupal stages, and then to the terrestrial adult mosquito stage (Al-Jaibachi et al, 2018a, 2018b. As with mosquitoes, C. flavicans exhibits both aquatic and terrestrial life stages, and thus the potential for ontogenic transference of MPs via this species from aquatic to terrestrial environments is high, and could accordingly impact terrestrial vertebrates.…”

“…Microplastics were stored as a stock suspension (2.5 mg mL -1 ) and mixed as per Al-Jaibachi et al (2018a). Chaoborus flavicans (1.0 -1.2 cm) larvae were purchased commercially (Northampton Reptile Centre, UK) and acclimated for 6 days in a laboratory at the University of Reading (19 ± 1 °C, 16:8 light:dark) on a diet of C. pipiens larvae in 5 L dechlorinated tapwater.…”

Microplastic and Organic Fibres in Feeding, Growth and Mortality of Gammarus pulex

“…Studies on MPs tend to be divided into those looking for evidence of ingestion and those looking at the impact of the MP on some aspect of the organism's biology, with mixed and sometimes conflicting results [16][17][18][19][20]. While the majority of studies have focused upon MP particles, those which focus upon MPFs have found similar results with good evidence for ingestion in marine crustaceans, Orchestia gammarellus, Carcinus maenas, Carcinus aestuarii and Nephrops norvegicus [21][22][23][24].…”