The main threats to insects are the expansion and intensification of agriculture, resulting in the loss or degradation of their habitats; excessive chemical contamination; the spread of invasive species; and global climate change. In the tropics, massive deforestation and agricultural intensification and expansion play a major role in the loss of biodiversity. The same threats apply to the dung beetles which have co-evolved for many millions of years in close association with the vertebrates whose dung they exploit. The extinction or scarcity of dung producers, especially mammalian herbivores and omnivores, can result in significant, detrimental changes in the composition of dung beetle assemblages. By manipulating, redistributing and degrading feces, dung beetles play a major role in the functioning of ecosystems. Their contributions include the replenishment of soil nutrients through the burial of feces, soil bioturbation that facilitates plant growth, and also the secondary dispersal of seeds. These ecological functions render important ecosystem services to humans, such as the biological control of livestock pests, reduction of greenhouse gas emissions from livestock, and soil enrichment through nutrient replenishment and the boosting of soil organic matter levels.
Numerous studies have reported the decline of dung beetles in various parts of the world, especially in the last 30 years. The gradual abandonment of traditional mixed grazing in Europe has led to the depletion of the trophic resources available to dung beetles. This abandonment has led to the reforesting of the landscape, which is detrimental to species of open habitats. These environmental changes have coincided with the increased use of veterinary parasiticides, whose residues often retain their insecticidal properties after defecation. Some residues can cause the near-immediate death of dung beetles while other residues can cause a greater or lesser degree of paralysis of the muscles of adults. This reduces their ability to locate feces, as well as decreasing female fertility and causing significant mortality of larvae, leading to a gradual and sometimes rapid decline in the number of individuals. The routine use of these parasiticides over long periods results in the decimation of exposed dung beetle populations and a reduction in their overall functional efficiency, leading in the long term to the accumulation of dry dung on the ground. The same effects have been observed on dung beetles after the regular use of some selective herbicides to prevent the invasion of pastures by bushy vegetation and forest trees.
The massive destruction and degradation of tropical forests has badly impacted their particularly diverse dung beetle faunas. Many forest dwelling dung beetles are in a precarious situation as most species have been unable to adapt to the grossly simplified grassy pasture habitats or the remaining fragmented and/or degraded forest habitats. In addition, the elimination or population crashes of many large forest mammals due to intensive hunting have resulted in the loss or scarcity of their feces for exploitation by forest dung beetles. The newly pastured areas and other simplified ecosystems are home to a very impoverished fauna, partly made up of exotic species intentionally introduced to compensate for the deficiency of ecosystem services. However, these introduced species can become invasive and compete with native dung beetles.