Brevicoryne brassicae Linn. is a species belonging to the order Hemiptera, not Acridoidea, and it is commonly known as the cabbage aphid. These small, soft-bodied insects are typically found on the undersides of leaves, especially on cruciferous vegetables such as cabbage, broccoli, and cauliflower. They are predominantly distributed in regions like northwest China, northern Inner Mongolia, and the northeastern central areas. However, in recent years, their occurrence has also been reported in eastern China, indicating a potential expansion of their range.
What are the damage characteristics of B. brassicae? The adults and nymphs feed by sucking sap from the host plant's leaves, stems, and seed pods. This feeding causes yellowing, curling, and even wilting of the leaves. Additionally, they excrete honeydew, which promotes the growth of sooty mold, further reducing plant health. Infestations can lead to stunted seedling growth, twisted peduncles, and deformed seed pods, ultimately resulting in lower yield and poor quality of the crop. More seriously, these aphids act as vectors for various viral diseases, and the damage caused by virus transmission is often more severe than the direct feeding damage.
Morphologically, B. brassicae has a short, rounded body (shorter than the tail piece) and is covered with a thick layer of wax, giving it a waxy appearance. This wax coating helps protect them from environmental stress and some insecticides.
In terms of habitat, B. brassicae does not have a woody overwintering host. Instead, it reproduces rapidly in warm, dry conditions, and winged forms migrate to new areas when population density increases. Winged individuals are attracted to yellow and orange colors, followed by green, while they are repelled by silver and gray. Optimal conditions for their development include temperatures between 18-25°C and relative humidity below 75%. There are over 70 natural enemies that help control their population, including ladybugs, lacewings, parasitic wasps, and certain species of ants. Among them, hoverflies and parasitoid wasps are particularly effective in long-term biological control.
Control methods include both cultural and chemical approaches. One effective practice is the use of yellow or yellow sticky traps to capture and reduce aphid populations. Reflective silver or white mulch can also be used to deter them from settling in the field. For chemical control, recommended options include 50% imidacloprid wettable powder diluted at 3000 times, 4.5% emulsifiable concentrate of cypermethrin at 3000 times, or 50% malathion wettable powder at 2000 times. It is important to rotate insecticides to prevent resistance development and ensure long-term effectiveness.
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