The negative effects of the residues of ivermectin in cattle dung using a sustained-release bolus on Aphodius constans (Duft.) (Coleoptera: Aphodiidae)

Abstract

-This paper reports the findings of two trials into the effects of the treatment of cattle with ivermectin slow-release (SR) bolus on the larval development of the dung beetle Aphodius constans Duft. Rectal faecal samples were collected prior to treatment and every 3 and 2 weeks in a first and second trial, respectively, and up to 156 days post-administration of the SR bolus. Faecal ivermectin concentration reached a peak at 63 days post-treatment (1427 ng⋅g -1 ) and ivermectin was detected up to 147 days post-treatment in the first trial (7.2 ng⋅g -1 ). First stage larvae of A. constans were reared with control or contaminated dung and adult beetles were counted after emergence. In the first trial, the comparison of pairwise samples showed that ivermectin prevented the development of larval A. constans until day 105, while at day 135 the rate of emergence was still significantly lower than the corresponding series of control (p < 0.05). In the second trial, the difference between control and treated series remained significant until 143 days post-treatment, with no emergence until 128 days post-administration of SR bolus to cattle. These results show the negative effect of ivermectin on the development of larval A. constans, even at a low concentration (38.4 ng⋅g -1 ). The administration of ivermectin sustained-release bolus to cattle was highly effective in killing dung beetle larvae for approximately 143 days after treatment. The results were similar when dung was obtained from a single animal kept alone, or from a blending of faecal pats obtained from a group of animals kept in field conditions during the whole trial period.ivermectin / sustained-release (SR) bolus / cattle / dung beetle / rate of emergence / environmental risk Vet. Res. 32 (2001) [421][422][423][424][425][426][427] 421

New screening test to predict the potential impact of ivermectin-contaminated cattle dung on dung beetles

“…were significantly reduced in dung pads 1-2 days after excretion while there was no effect starting on days 13/14 [26]. These results were also similar with those obtained in independent experiments in which ivermectin was applied as a sustained-release bolus [5]. In one trial, the concentration of ivermectin 135 days after treatment (i.e.…”

“…(Aphodiinae). This species was selected on the basis of its wide distribution in Europe, its long activity period and short larval development time and because it is known to have a high sensitivity to veterinary avermectins [5,15,16].…”

Use of anthelmintics in herbivores and evaluation of risks for the non target fauna of pastures

“…Normally, about 80% of the ammonia release from dung pats is lost during the first five days, but when sufficient numbers of beetles are present for quick burial, the loss is reduced to 5-15% and permits the use of this N by plants for up to two years. Under such conditions, pats become progressively soil annexes, with the network of tunnels making colonisation of pats by edaphic fauna easier [25]. Tunnels made by beetles improve the oxygen supply to coprophagous flies but also provide runways so predatory Staphylinids can get at the flies [105].…”

“…Faecal residues or metabolites of drugs belonging to the benzimidazole and levamisole/morantel groups are thought to be relatively harmless to dung fauna [81,110], on the contrary to other anthelmintics such as coumaphos, dichlorvos, phenothiazine, piperazine [12,64], synthetic pyrethroids [10,115], and most macrocyclic lactones [25,50,99,100,102] which have been shown to be highly toxic for dung beetles.…”

“…Several factors can modify the environmental risks: (i) The amount of the active agent which enters the environment; this amount depends on the route or delivery system of administration [50], and on the physiology of the treated animals [3,4]; (ii) The concentration and persistence of the drug in the faeces, and the total amount of droppings from treated animals compared to the total faecal deposits in the pasture [30,81]; (iii) Environmental factors (light, rainfall, temperature…) and the coincidence of deposits with activity of non-target organisms [30,41]; (iv) The susceptibility of organisms, some taxa are more susceptible than others, and some are highly resistant [24,25,28,29,35,39,41,112,113].…”