Using the DEFRA ecosystem services assessment framework, we estimated the economic value of a suite of four ecosystem services, delivered by dung beetles, to the U.K. cattle industry and to individual cattle farmers. We also estimated the potential economic benefits delivered by dung beetles if they were protected by agri‐environment schemes, under organic legislation, or if farmers stopped treating adult cows with anthelmintics.

Method critique

In this paper. we report a novel application of the ecosystem services framework (DEFRA, 2007a,b). Owing to limited data availability, our model only quantifies a small suite of services and is based on a number of oversimplifications and assumptions. As such, we see our values as preliminary estimates rather than definitive figures. Below, we highlight some of the limitations of our analyses and provide recommendations for closing the gaps in the ecological and economic data, which formed the basis of our valuations.

To better estimate the effects of anthelmintics on dung beetle functioning, we used data from a small mesocosm experiment. However, the selection of dung beetle communities was informed by species‐specific adult and larval survival data and dung beetle collection data from farms under different land management practices. This ensured that we attempted to include potential long‐term population trends into our model, which would have been largely driven by lethal and sub‐lethal impacts of anthelmintic on dung beetles. In our ‘Medium diversity,’ community, both species richness (n = 5) and abundance (n = 30) per dung pat were probably lower than is representative (Rosenlew & Roslin, 2008). Additionally, we excluded less common endocoprid species and small paracoprids (e.g. Onthophagus spp.), which may be functionally important and highly sensitive to some anthelmintics, but may also be abundant on some agricultural pastures (Beynon et al., 2012a; Beynon, 2013). Nevertheless, the overarching functional efficiency of the large paracoprid Geotrupes stercorarius L. would perhaps have masked any potential effects of including/excluding additional endocoprids or small paracoprids [as in Rosenlew and Roslin (2008)]. However, this meant that our estimates were probably conservative and ensured that we have confidence that the communities used to inform our model were representative of improved agricultural pastures, rather than of unimproved pastures or semi‐natural/natural habitat, where benefit values may be much greater. In addition, regular treatment of cattle with anthelmintics is likely to suppress dung beetle populations, even when dung containing those anthelmintics (which affect dung beetles) in a sufficient concentration to impact dung beetles is not being excreted: we did not take this into account in our model. We also based our estimates on the functioning of an early‐summer dung beetle community, which may be functionally less efficient than spring or autumn communities and more efficient than the midsummer community (Landin, 1961; Roslin, 2001; Lee & Wall, 2006). We purposefully selected an early‐summer community, with species that overlap amongst seasons, to be as representative as possible.

However, it is also important to note that, after changing patterns of anthelmintic use to benefit dung beetles, the recovery in functioning, and therefore ecosystem service benefits, may not be immediate. Barriers to re‐colonisation (e.g. local extinctions or dung beetle species‐specific dispersal limitations) may delay, or even prevent, swift population recovery, and/or functional recovery.

Many of our value estimates relied upon a number of broad generalisations owing to a lack of robust, UK‐centric data. In particular, information on ecological interactions between dung beetles and pest flies remains exceptionally limited. We assumed that dung beetle effects on pest fly and gastrointestinal parasite control increased proportionally with dung removal. However, this may not be the case (Nichols & Gomez, 2014), and we may have over‐estimated, or under‐estimated, dung beetle contributions to pest fly and gastrointestinal parasite control.

In particular, our estimates of pest fly control mediated by dung beetles rely on a large number of assumptions. These estimates probably contain some of the largest sources of uncertainty in our models. Owing to a lack of robust data, and in agreement with Fincher (1981) and Losey and Vaughan (2006), we did not take into account the fact that anthelmintics that are toxic to dung beetles will also be toxic to dung‐breeding pest flies. Therefore, we may have been overestimating dung beetle benefits for pest fly control in our ‘Current’ scenario. For our ‘Alternative’ scenarios, if fewer of the more toxic anthelmintics were employed, pest fly abundance may increase over and above any decreases in pest fly abundance owing to increased dung removal mediated by dung beetles. It is likely that anthelmintics less toxic to dung beetles will also be less toxic to dung‐breeding flies (Floate et al., 2001; Boxall et al., 2007). However, flies are generally more sensitive to anthelmintics than dung beetles (Ridsdill‐Smith, 1988; Doherty et al., 1994; Wardhaugh et al., 1998) so may be suppressed by anthelmintics that are less‐ or non‐toxic to dung beetles (Webb et al., 1991): but these anthelmintics may correspondingly be less effective for pest fly control (Doherty et al., 1994; Strong & Wall, 1994; Floate et al., 2001). Nevertheless, we assumed that dung removal mediated by dung beetles, together with the use of anthelmintics that are toxic to pest flies (but less or non‐toxic to dung beetles), may deliver net pest fly control similar to that delivered by the more toxic anthelmintics alone. To further control pest flies, farmers could also increase reliance on off‐host control (Wall, 2007) or specific fly control treatments (e.g. synthetic pyrethroid ear‐tags) but these chemicals may still be toxic to dung beetles (Krüger et al., 1998; Wardhaugh et al., 1998).

When calculating the benefits mediated by dung beetles on increased soil nutrients, we assumed that the activity of dung beetles would increase soil nutrients relative to the amount of dung removed. Thus, we assumed that additional nutrients would otherwise be lost by, for example, leaching into water courses (Hooda et al., 2000) or as greenhouse gas emissions (Penttilä et al., 2013), whereas nutrients may eventually be incorporated into soil by other means [e.g. by soil fauna (Atiyeh et al., 2000)].

Additional potential disbenefits, such as impacts on animal welfare and production associated with changing patterns of anthelmintic usage, may also be underestimated. For example, there may be production losses in adult dairy animals as a result of gastrointestinal parasites (Gross et al., 1999; Murphy et al., 2006). However, issues of parasite resistance to conventional anthelmintics (Jabbar et al., 2006) and potential human health concerns of anthelmintic residues in meat (Cooper et al., 2012) and milk (Moreno et al., 2005) means that savings to individual farmers, and at a policy level, could be greater than we have estimated here.

Data required for the economic valuation component of this research were based on actual market values (e.g. market prices for milk and meat) and livestock numbers. It is important to consider that these market values can be highly variable within and across years. Any variation in such values will obviously impact our ecosystem service valuation. Although it would have been desirable to provide rigorous sensitivity analyses, or confidence intervals, the lack of robust data meant that such an assessment of the range of benefits would have been difficult to implement in a systematic and objective manner. The reason that we only report a lower bound estimate is because this estimate is based upon justifiable assumptions.