Food and drug retailers were the worst performers of the day on Wednesday after a disappointing trading update from supermarket titan Tesco weighed on sentiment.Headline group sales (excluding petrol) in the first quarter grew 2.7% at the FTSE 100 group, but were flat at constant currency rates and sank 2.2% on a like-for-like (LFL) basis.The domestic market in the UK saw LFL sales fall by 1.0%, worse than the 0.7% decline that consensus estimates had pointed to, due to weak sales in the non-food category, consumer electronics specifically. Meanwhile, while the performance in food broadly strengthened over the preceding three months, the horsemeat scandal that swept through the UK did have an impact on Tesco's frozen foods and chilled convenience meals, the company admitted.Supermarket peers Morrison and Sainsbury were also firmly out of favour today, along with grocery delivery group Ocado.High Street chocolate shop Thorntons and bakery chain Greggs were also in the red.Top performing sectors so far todayBottom performing sectors so far todayFood & Drug Retailers 4,395.20 -3.49%Forestry & Paper 8,934.84 -3.49%Financial Services 6,807.83 -2.89%Gas, Water & Multiutilities 5,772.26 -2.72%Construction & Materials 3,692.85 -2.25%BC