They achieved the status after being tested against 10 other ready to use products for controlling aphids by Which? Gardening.
Bayer Ultimate Fruit and Vegetable Bug Killer scored 68 per cent, Westland Earth Matters Insect Control scored 68 per cent and Doff Greenfly and Blackfly Killer scored 64 per cent.
Westland Horticulture brand manager Amy Lawrence said: "Aphids are one of the most common gardening pests and can cause damage to plants by feeding on sap, causing the plant to weaken, distorting its growth.
"Due to the recent mild weather, aphid infestations are common and set to increase, meaning Resolva Bug Killer is a must-have buy for the coming season."
Meanwhile, Westland and Syngenta have donated product to Christchurch C of E Infant School in Surrey, where QVC TV presenter Julia Roberts commemorated the 75th birthday of the British Polio Fellowship this month by planting a garden. She is an ambassador for the charity, having contracted polio aged 14 months.
Roberts is working with The British Polio Fellowship on their ‘Sowing the Seeds of Hope’ campaign because polio is still posing a real threat to people in the UK in the form of Post Polio Syndrome.