Limitations of allometry, morphometry, and fluctuating asymmetry in detecting environmental stress caused by lead soil contamination in aphids under field conditions
2024
Bruna Corrêa-Silva | Tiago Morales-Silva | Lucas Del Bianco Faria
ABSTRACT One of the tools used to investigate the influence of environmental contaminants and other stresses on the development of organisms is the analysis of morphometric traits used to detect changes in growth and size patterns. To evaluate the effects of the heavy metal lead (Pb) present in experimentally contaminated soil on the morphometric traits of the aphid Brevicoryne brassicae (L.) reared on cultivated Brassica oleracea L. (var. acephala), we analyzed three different metrics: morphometry, allometry, and fluctuating asymmetry (FA). Additionally, we aimed to assess the effectiveness of these analyses in detecting environmental stress. We cultivated kale plants in soil contaminated with the maximum allowable limit of Pb for local soils in Brazil, and the colonization of plants by aphids occurred naturally under field conditions. After collection, we photographed and measured the antennae, tibiae, and total body length of aphids from the control and contaminated treatments. We observed no significant differences in the allometry and morphometric analysis, and the presence of the contaminant did not result in any observed FA. The study demonstrated that the morphometric trait analyses employed were not effective in detecting environmental stress resulting from field exposure of aphids to Pb in soil, since these insects suffered a reduction in their population density in the presence of Pb, as indicated in our previous findings. This result diverges from those found in studies conducted under laboratory conditions. We discussed mechanisms of metal accumulation, detoxification in aphids, and population aspects in natural conditions.
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