Pollution impacts on water bugs

The type of water pollution can be of a chemical, physical or microbiological nature and the consequences can compromise the health of the flora and fauna involved

by Lorenzo Ciotti
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Pollution impacts on water bugs

The type of water pollution can be of a chemical, physical or microbiological nature and the consequences can compromise the health of the flora and fauna involved, including humans, harming the ecosystem and water reserves for drinking.

There are two main routes through which pollutants reach the water: either directly or indirectly. Direct pollution occurs when polluting substances are poured directly into water courses without any purification treatment.

The indirect route, on the other hand, occurs when pollutants arrive in watercourses via air or soil. The study: Pollution impacts on water bugs (Nepomorpha, Gerromorpha): state of the art and their biomonitoring potential, published on the Environmental monitoring and assessment, tries to retrospect this implications.

The team of researchers explains: "As water pollution poses an increasing risk worldwide, it is timely to assess the achievements of the aquatic macroinvertebrate ecotoxicology to provide a sound basis for the discipline's future and support the development of biomonitoring.

Aquatic and semi-aquatic bugs are ubiquitous in almost all water types, sometimes in high densities, and play a significant role in organic material turnover and energy flow. Nevertheless, they are ignored in the water pollution biomonitoring schemes.

Here, based on 300 , we review and evaluate the effects of chemical pesticides, microorganism-derived pesticides, insecticides of plant origin, heavy metals, eutrophication, salinization and light pollution which are summarized for the first time.

Our review encompasses the results of 100 laboratory papers and 39 seeds -field / field experiments with 47 pesticides and 70 active ingredients. Pyrethroids were found to be more toxic than orga nochlorine, organophosphate and neonicotinoid insecticides to water bugs, like other macroinvertebrate groups.

Additionally, in 10 out of 17 cases, the recommended field concentration of the pesticide was higher than the LC50 values, indicating potential hazards to water bugs. The recommended field concentrations of pesticides used in mosquito larvae control were found non-toxic to water bugs.

As very few replicated studies are available, other findings on the effects of pesticides cannot be generalized. The microorganism-derived pesticide Bti appears to be safe when used at the recommended field concentration. Data indicates that plant-derived pesticides are safe with a high degree of certainty.

We have identified three research areas where water bugs could be better involved in water biomonitoring. First, some Halobates spp. are excellent, and Gerris spp. are promising sentinels for Cd contamination. Second, Micronecta and, to a certain extent, Corixidae species composition is connected to and the indicator of eutrophication.

Third, the species composition of the Corixidae is related to salinisation, and a preliminary method to quantify the relationship is already available. Our review highlights the potential of water bugs in water pollution monitoring. "