Phenoloxidase activity and electroantennography – methods to measure sublethal effects of particulate stressors in insects

Frederic Hüftlein1, Matthias Schott1, Christian Laforsch
1 Tierökologie I,

O 4.3 in Methods in Ecology and Environmental Research

14.10.2021, 09:27-09:33, H 36

The introduction of traffic emissions is a major factor for species decline worldwide. They are mainly derived from incomplete combustion from exhaust engines, brake wear, and tire wear. We grasp to understand and unravel the impacts and, in the case of harmful substances, the mode of action of these particles on organisms and whole ecosystems. A first step in ecotoxicology is to assess a substance's acute toxicity, with often high, unrealistic concentrations, when orally ingested or applied on an organism's surface. A next possible step is to identify sublethal effects of lower environmentally relevant concentrations. We want to unravel the effects of exhaust and brake abrasion particles on the buff-tailed bumblebee Bombus terrestris and the larvae of the non-biting midge Chironomus riparius. One point of reference is measuring the level of phenoloxidase in the hemolymph of the respective insect. Pathogens or foreign particles induce melanin deposition around them, resulting in encapsulation. Phenoloxidase is a critical enzyme for melanin synthesis and, therefore, a good proxy for induced stress. Another point of reference we measure is the neuronal responsiveness in the insect's antenna after exposure to exhaust particles. Reduced ability to sense volatiles could result in bumblebees having difficulties finding suitable flowers or back to their nest. The measurement of neuronal responsiveness is being achieved by assessing the strength of the amplitude after a stimulus. Revealing the effects of stressors on organisms is crucial for understanding possible changes in biodiversity and management solutions concerning the protection of organisms.


Keywords: particulate stressors, sublethal effects, phenoloxidase, electroantennography, insects

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