Effects of Atmospheric Pollution on a Front Line Species

Background

Atmospheric pollutants such as industrial emissions, crop sprays can be deposited long distances from their points of release. There are three routes of entry for such pollutants into animals: respiratory absorption of inhaled airborne material, skin absorption from contact with contaminated substrates, and absorption through the gut from the ingestion of contaminated material. The experiments described here are concerned with absorption due to ingestion and contact. The effects of acidic gases such as sulfur dioxide on epiphytic lichens and algae have long been known. Recently it has become apparent that these organisms can accumulate large amounts of other atmospheric pollutants such as heavy metals, organic compounds, and radionuclides. Many arthropod assemblages are associated with epiphytic algae and lichens, most using these as a source of nutrients. In this study one such group, the bagmoths (Lepidoptera: Psychidae), were used for measuring biological effects of atmospheric pollutants. Bagmoth larvae were used as they constitute a "front-line" or sentinel group of indicator organisms because of the ability of their algal diet to absorb large quantities of atmospheric pollutants.

The global distribution of the Psychidae ranges from Finland to the tip of South America. They are commonly referred to as bagmoths because their larvae construct portable dwellings from silk coated externally with their various pabulae. These bags protect the larvae from desiccation and provide them with camouflage enabling them to avoid the attention of predators.

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Conclusions

There are many features of the biology of Luffia ferchaultella that make it a useful organism in ecotoxicological studies. Of most importance for assessing the toxic effects of atmospheric pollutants is that the diet of its larvae is capable of sequestering such pollutants, resulting in measurable detrimental effects on their feeding. Results of laboratory experiments designed to simulate pollution from agricultural sprays and vehicle exhaust emissions identified feeding as the most sensitive endpoint of those examined. A field transect demonstrated that larvae supplied with algae collected from an environment impacted by atmospheric pollution exhibited reduced feeding compared with those fed algae from a "clean" control site.

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