Effects of chemical and hydrological stress on the wing morphology of a damselfly.

Dragonflies and damselflies are exposed to various anthropogenic stressors in the aquatic-terrestrial ecosystem, which can affect their development and fitness. The symmetry of their wings, shaped during the aquatic larval stage, can serve as an indicator of environmental stress during development. Recent advances in computer-vision now provide the opportunity to standardize and enhance the precision of 2D assessments of entire wings, including many structural parameters, enabling a more reliable comparison of the effects of multiple anthropogenic stressors. We investigated the effect of 3 anthropogenic stressors on the fluctuating wing asymmetry of the damselfly Coenagrion puella: (i) Exposure to the agricultural insecticide chlorantraniliprole in a climate chamber experiment, (ii) alteration of the aquatic community with the mosquito control agent Bti (Bacillus thuringiensis israelensis), and (iii) altered hydrological regimes, both of which were applied in a floodplain mesocosm experiment in a full 2-factorial design. We found changes in wing size and several asymmetry parameters in response to the insecticide and altered hydrological regimes, whereas Bti treatment increased the number of cells in front wings. Our results show that damselflies' wing morphology and symmetry can be affected by anthropogenically induced stress in aquatic ecosystems. The intensity of stressor effects varied across treatments, with altered hydrology causing the strongest changes in wing size and asymmetry.