Resource stocks are higher as commodity prices rise. Oil explorer and producer Salamander Energy and platinum specialist Aquarius Platinum are among the risers.However, not all commodity stocks are joining the party, with oil explorer Melrose Resources among the fallers.Investors also have an appetite for food stocks, with sugar firm Tate & Lyle and Hovis bread maker Premier Foods among the top risers.FTSE 250 - RisersYell Group (YELL) 15.70p +8.58%Redrow (RDW) 114.00p +6.54%CSR (CSR) 298.80p +6.37%Salamander Energy (SMDR) 234.00p +5.98%Melrose (MRO) 271.90p +5.59%Tate & Lyle (TATE) 429.60p +5.01%Morgan Crucible (MGCR) 204.10p +4.99%Hikma Pharmaceuticals (HIK) 801.50p +4.77%Aquarius Platinum Ltd. (AQP) 292.10p +4.70%Premier Foods (PFD) 16.75p +4.69%FTSE 250 - FallersRathbone Brothers (RAT) 840.00p -2.55%Laird (LRD) 127.00p -2.46%International Public Partnerships Ltd. (INPP) 112.40p -2.43%Computacenter (CCC) 280.20p -1.89%Melrose Resources (MRS) 299.10p -1.87%Jardine Lloyd Thompson Group (JLT) 568.50p -1.73%JD Sports Fashion (JD.) 775.00p -1.65%BTG (BGC) 197.70p -1.64%Moneysupermarket.com (MONY) 72.45p -1.50%Davis Service Group (DVSG) 375.00p -1.45%