In addition, the undergrowth in the oil palm plantations, proximity to larger blocks of forest and the complexity of forest fragment edges may affect the pest and pest predator abundances, and the impact of these factors also deserves further investigation. Although we found little evidence that conserving riparian forest provides a pest control service, it is equally important that we found no pest “disservice” created by retaining the Raf inhibitor reserves. This evidence should reassure oil palm managers concerned about negative impacts of conserving non-crop habitat. The extent to which riparian reserves provide other ecosystem

services aside from hydrological services also deserves further attention. For example, in our study area in Borneo, aboveground biomass is higher in riparian reserves compared to adjacent areas of oil palm (Singh, 2012). Combining all the possible costs and benefits of conserving riparian reserves will

be necessary to inform management guidelines and policy. The results of studies using artificial mimics should be interpreted with caution, as the extent to which attack marks on mimics correlate with real predation LY294002 in vivo rates remains unclear (Howe et al., 2009). We found that bird attacks dropped when the mimic no longer resembled a prey item, but that there was no change in arthropod attacks, suggesting that attack marks from birds are more likely to correspond to predatory behaviour. This is probably because birds rely more on visual cues, whereas arthropods rely much more on olfactory cues and are unlikely to be mistaking

the mimics for potential prey (Tvardikova & Novotny, 2012). It is possible that the plasticine mimics elicit a response from foraging arthropods that would not attack pest species why on oil palm. Therefore, we suggest that attack rates on plasticine pest mimics are indicative of density or activity of foraging arthropods rather than an actual predation rate. We did not find lower attack rates from either birds or arthropods on aposematic (warning) mimics. The dependence of arthropods on olfactory cues may also explain this result, whereas the lack of an effect of colour on bird attacks may be because frugivorous species mistook the mimic for the red colour of the ripe oil palm fruits; several bird species within oil palm plantations are known to feed on palm fruit (Chenon & Susanto, 2006). It is not possible to determine from our data whether the attacks on brown and red mimics are similar because they both attract the attention of the same bird species, or those with different feeding behaviours. We hope that this methodological assessment will provide a useful insight for future such studies.