Implications of Endectocide Residues on the Survival of Aphodiine Dung Beetles: A Meta-Analysis

Citation

Finch, D., Schofield, H., Floate, K.D., Kubasiewicz, L.M., Mathews, F. (2020). Implications of Endectocide Residues on the Survival of Aphodiine Dung Beetles: A Meta-Analysis. Environmental Toxicology and Chemistry, [online] 39(4), 863-872. http://dx.doi.org/10.1002/etc.4671

Plain language summary

Cattle treated with parasiticides can excrete residues in dung harmful to dung-breeding insects, but comparing results across difficult studies can be difficult. Studies may differ in experimental approach, type of parasiticide (eprinomectin, doramectin, ivermectin, moxidectin) and how the parasiticide is formulated for application (injectable, pour‐on, spiked). To compensate for these differences, we performed a quantitative meta‐analysis that combined results across 22 studies to assess the overall effect of parasiticide residues on the occurrence (presence or absence) and abundance of dung beetles. Our results showed that residues were associated with an increase in the number of adult beetles, which indicated to us that adults tended to be attracted to dung with residues. Conversely, our results showed that dung beetle larvae were less likely to occur in dung containing residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. When we examined individual types of parasiticides, only ivermectin was associated with a significant decline in numbers of both adults and larvae, possibly because our meta-analysis contained relatively few studies testing the effects of eprinomectin, doramectin, or moxidectin. In laboratory studies, only dung “spiked” with parasiticides reduced the abundance of larvae. In field studies, only pour‐on applications were shown to reduce the abundance of larvae. Results of our meta-analysis further establish the harmful effects of parasiticide residues in dung of cattle on dung beetles, provide strong evidence on the consequences of different application methods, and emphasize the need for standardized methodological techniques in future studies.

Abstract

It is often difficult to compare studies examining the effects of endectocides on dung fauna because of different experimental approaches, for example, active ingredients (eprinomectin, doramectin, ivermectin, moxidectin) and formulations (injectable, pour-on, spiked). To gain a better understanding, we performed a quantitative meta-analysis using 22 studies to assess the overall effect of endectocide residues on the occurrence (presence or absence) and abundance of aphodiine dung beetles. Our results document a positive effect on the occurrence of adult beetles, indicating that adults tend to be attracted to dung with residues. Conversely, larvae are less likely to occur in the presence of residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. Abundance of adult and larval stages was shown to be significantly reduced in dung containing residues. When individual endectocides were compared, only ivermectin demonstrated a significantly negative effect on the abundance of both adults and larvae, possibly owing to a small sample size for other agents. In laboratory studies, only dung “spiked” with endectocides reduced the abundance of larvae, whereas during field research, only pour-on applications were shown to reduce the abundance of larvae. The present study further documents the nontarget effects of endectocide residues on dung-dwelling organisms, provides robust evidence on the consequences of different application methods, and emphasizes the need for standardized methodological techniques in future studies. Environ Toxicol Chem 2020;39:863–872. © 2020 SETAC.

Publication date

2020-04-01

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