Author Contributions
TMB designed the field experiment. RH, FZ, MH, TMB, executed the first phase of the field experiment. All authors contributed to maintenance of the second phase of the experiment. RH, SEH, JDL, FZ, KS, MH, RJ, TMB collected field data. SEH and RH analyzed data. RH led the writing of the manuscript, in close collaboration with SEH, JDL and TMB. All co-authors contributed critically to the manuscript and approved the final version for publication.