Heifers were treated with the recommended doses of ivermectin: 0.2 mg/ kg bw by subcutaneous injection or 0.5 mg/kg bw by pour-on. An analytic procedure is described and used for the detection of ivermectin residues excreted in dung. A large amount of the higher pour-on dose was excreted during the first five days after dosing due to a more rapid distribution to intestinal contents. Later faecal concentrations after the pour-on treatment were lower than those found after subcutaneous injection. No degradation of ivermectin was detected in pats exposed in the field for up to 45 days. Ivermectin excreted in dung voided 1–2 days after both treatments significantly reduced the number of dung inhabiting larvae of Aphodius spp. (Coleoptera: Scarabaeidae), but no effect was seen in dung deposited 13–14 days after treatments. Development of cyclorrhaphan larvae was inhibited in dung deposited up to 28–29 days after subcutaneous injection treatment, but only inhibited in dung deposited up to 13–14 days after pour-on treatment. The numbers of Nematocera larvae were not affected. In a laboratory bioassay the Diptera Musca autumnalis DeGeer and Haematobia irritans (Linnaeus) suffered higher mortality in dung from heifers treated by the subcutaneous injection 13–14 days earlier than in dung from heifers treated by pour-on at the same time. After subcutaneous injection, a significant reduction in the rate of decomposition was found in dung from heifers treated 1–2 days earlier, whereas pour-on led to a delayed decomposition in dung collected up to 13–14 days after treatment.
Coastal benthic biodiversity is under increased pressure from climate change, eutrophication, hypoxia, and changes in salinity due to increase in river runoff. The Baltic Sea is a large brackish system characterized by steep environmental gradients that experiences all of the mentioned stressors. As such it provides an ideal model system for studying the impact of on‐going and future climate change on biodiversity and function of benthic ecosystems. Meiofauna (animals < 1 mm) are abundant in sediment and are still largely unexplored even though they are known to regulate organic matter degradation and nutrient cycling. In this study, benthic meiofaunal community structure was analysed along a salinity gradient in the Baltic Sea proper using high‐throughput sequencing. Our results demonstrate that areas with higher salinity have a higher biodiversity, and salinity is probably the main driver influencing meiofauna diversity and community composition. Furthermore, in the more diverse and saline environments a larger amount of nematode genera classified as predators prevailed, and meiofauna‐macrofauna associations were more prominent. These findings show that in the Baltic Sea, a decrease in salinity resulting from accelerated climate change will probably lead to decreased benthic biodiversity, and cause profound changes in benthic communities, with potential consequences for ecosystem stability, functions and services.
The effect of ivermectin treatment of cattle on the rate of dung beetle colonization of cow pats was assessed by pitfall trapping in Denmark, Tanzania and Zimbabwe. Ivermectin was injected subcutaneously into heifers at the recommended dose of 0.2 mg/kg body weight, and dung to be used as bait in pitfalls was collected at intervals after treatment. In one experiment in Denmark, species of the scarab beetle Aphodius and the hydrophilids Sphaeridium and Cercyon, preferred control dung from untreated cattle; no preference was found in two other experiments, involving some of the same species. In the Tanzanian trials, the overall tendency for scarabaeid beetles was to prefer control dung. In Zimbabwe, two scarabaeid species (Euoniticellus intermedius (Reiche) and Liatongus militaris (Castelnau), both belonging to Oniticellini) were particularly attracted to dung from treated cattle; two other scarabaeids showed no preference. It is concluded: 1. That ivermectin therapy can affect the rate of dung colonization by attracting or repelling beetles. 2. That the responses are probably not caused by ivermectin per se, but by some side effect, the nature of which is obscure and unpredictable with our present knowledge.
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