Histopathological changes in the perivisceral fat body of Rhinocricus padbergi (Diplopoda, Spirobolida) triggered by biosolids

Abstract

Human activities generate a great amount of sewage daily, which is dumped into the sewer system. After sewage-treatment processes, sewage sludge is generated. Such byproduct can be treated by different methods; the result of treatment is a stabilized compost of reduced pathogenicity that has a similar inorganic chemical composition to the raw sewage sludge. After such pretreatment, sewage sludge is called a biosolids, and it can be used in agriculture. In this contest, the present study evaluated the effects of a sample of biosolids on the perivisceral fat body of a diplopod. These invertebrates are soil organisms that play an important role in the dynamics of terrestrial ecosystems, and as a consequence, they are in contact with xenobiotics present in this environmental compartment. Special emphasis is given on the interpretation of the effects of complex mixtures in target organs of diplopods. A semiquantitative analysis for the evaluation of histopathological changes in the perivisceral fat body was proposed. The sample-induced histopathological and ultrastructural changes in individuals exposed to it, and the severity of the effects was positively related to the exposure time, resulting in the deaths of exposed individuals after 90 days. Thus, the results indicate the need for caution in the use of biosolids as well as the need for improving waste management techniques, so they will produce environmentally innocuous final products.

Histologic lesions of giant African millipedes (Archispirostreptus gigas) from a zoological institution

“…Diplopod pathology should be more thoroughly investigated as they are the third-most important detritivores (after termites and earthworms) 14 and are keystone species in many terrestrial ecosystems, often serving as a bioindicators for the evaluation of pollutants in the environment. 9,21 Millipedes are also widely studied models in ecological, engineering, and medical fields with many publications utilizing them for research on body segment development, morphology and locomotion dynamics, 10 analysis of secretions for antimicrobial and other industrial and medical properties, 1,11,15,16,23,28,35 soil ecotoxicology, 6 and gut microbiota and enzymatic processes for organic matter transformation. 14,37 Importantly, millipedes are found in zoo settings, involved in outreach and educational programs, and are now considered a nontraditional pet; therefore, interest in optimizing husbandry and veterinary care for these invertebrates will become increasingly relevant.…”

“…14 Although millipedes can be highly destructive agricultural pests, they are still considered keystone species in their ecosystems and are used as indicator species in ecotoxicology studies, 6 evaluating soil contamination and other environmental pollutants. 9,14,36 Millipedes have varied morphologies and sizes, some with vibrant colors, and are generally docile, making them ideal for zoological exhibits and educational encounter programs. They may be housed successfully in mixed species exhibits as they are nonaggressive, and most are herbivorous.…”

“…14 Although millipedes can be highly destructive agricultural pests, they are still considered keystone species in their ecosystems and are used as indicator species in ecotoxicology studies, 6 evaluating soil contamination and other environmental pollutants. 9,14,36…”