Elevated atmospheric CO₂ adversely affects a dung beetle’s development: Another potential driver of decline in insect numbers?

Abstract

Insect declines have been attributed to several drivers such as habitat loss, climate change, invasive alien species and insecticides. However, in the global context, these effects remain patchy, whereas insect losses appear to be consistent worldwide. Increases in atmospheric CO2 concentrations are known to have indirect effects on herbivorous insects, but the effects on other insects are largely unexplored. We wondered if elevated atmospheric CO2 (eCO2) could influence the growth and survival of insects, not via rising temperature, nor through their changes in food quality, but by other means. Rearing tunnelling dung beetle Euoniticellus intermedius (Reiche, 1848) at pre‐industrial (250 parts per million [ppm]), current (400 ppm) and eCO2 levels (600 and 800 ppm), we found that exposure to eCO2 resulted in longer developmental times and increased mortality. Elevated CO2 also caused reduction of adult size and mass which is detrimental to dung beetle fitness. Additional results showed associated increases in CO2 levels inside dung brood balls, dung pH and respiration rates of the soil surrounding the developing dung beetles (CO2 flux). We thus hypothesize that elevated CO2 increases competition for O2 and nutrients between soil microbiota and subterranean insects. Given that many insect orders spend at least part of their life underground, our findings indicate the possibility of a negative ubiquitous effect of eCO2 on a large portion of the earth's insect biota. These findings therefore suggest an important area for future research on the soil community in the context of atmospheric change.

The response of ants to climate change

“…In contrast, effects on animals have received much less attention and, for ants, the effects are virtually unknown. Recent work by Tocco et al (2021), however, demonstrated that elevated CO 2 can increase dung beetle developmental time, increase mortality and result in reduced adult body size and mass. Because many ants also spend a large proportion of their life, including their developmental phase, underground, it is possible they will respond similarly.…”

“…Yet, currently CO 2 levels inside ant nests belowground can be much higher than background levels (e.g., 1-3% in leafcutter nests) and this does not pose a problem (Römer et al, 2017(Römer et al, , 2018-as is the case for some other insects too (e.g., termites, tiger beetles, Tocco et al, 2021). Ants also manage CO 2 levels via nest architecture and ventilation systems, and ground-nesting ants can move brood to shallower depths (and therefore lower CO 2 levels) when necessary (Kleineidam & Roces, 2000;Römer et al, 2018).…”

Importance of restoration of dung beetles in the maintenance of ecosystem services

“…Dung beetles (Coleoptera: Scarabaeidae) are among the most recognizable of the dung fauna. Dung beetles occur globally (Frank et al, 2018) and contribute to important ecosystem functions (Thomas, 2001) but are facing multiple threats (Tocco et al, 2021).…”

“…Dung beetles (Coleoptera: Scarabaeidae) are among the most recognizable of the dung fauna. Dung beetles occur globally (Frank et al., 2018) and contribute to important ecosystem functions (Thomas, 2001) but are facing multiple threats (Tocco et al., 2021). Despite their importance, very little attention has been paid to the restoration of these charismatic insects where they have been lost.…”

Insect Annihilation: Causes for Decline and Strategic Conservation Plan in 21st Century

“…Dung beetles become smaller as CO2 levels rise in the atmosphere. Increased CO 2 in the atmosphere makes dung beetles smaller (Tocco et al 2021). Carbon dioxide levels in the atmosphere are rising, which reduces monarch tolerance and increases parasite virulence by altering the medicinal properties of milkweeds (Dicker et al 2018) Technological interventions: Mobile telecommunication antenna emits electromagnetic radiation which influences the abundance and composition of wild pollinators.…”