Whiteflies are a major problem for tomato growers, causing significant crop damage and financial losses. Traditional pest control relies heavily on insecticides, but these can have negative environmental impacts and often lead to pest resistance. This has driven research into alternative, more sustainable methods of pest management, such as using companion plants – growing specific plants alongside the main crop to deter pests or attract their natural enemies.
A recent study by researchers at Sophia Agrobiotech Institute investigated the potential of Tagetes (marigold) species and Crotalaria juncea (sunn hemp) as companion plants for controlling whiteflies (Bemisia tabaci) on tomato plants. The study began by confirming that whiteflies readily settle and lay eggs on tomato plants alone, establishing a baseline for comparison. When either Tagetes or Crotalaria was introduced alongside the tomatoes in a controlled environment, a significant reduction in both whitefly settlement and egg-laying was observed. This indicated that both plants had a deterrent effect.
To understand how these plants were deterring the whiteflies, the researchers designed a follow-up experiment. They altered the arrangement of the plants to differentiate between two possible mechanisms: a physical barrier preventing whiteflies from reaching the tomatoes, or a chemical repellent effect that actively discouraged them. The results suggested a combination of both. Tagetes species appeared to act as a partial barrier, while also releasing chemicals that repelled the whiteflies. Interestingly, Crotalaria seemed to function more as a "sinkhole," attracting and trapping the pests.
Read more at Natural Science News
