Green peach aphid

〔Pest scientific name〕Myzus persicae (Sulzer)

〔Damaged crops〕The green peach aphid is a polyphagous pest. On vegetables it can damage radish, Chinese cabbage, rapeseed, mustard, kohlrabi, eggplant, pepper, tomato, cucurbits, legumes, spinach, etc. On fruit trees, peach, plum, apricot, cherry, etc. suffer severely.

〔Pest identification〕Adult aphids and nymphs gather on the underside of leaves to suck sap, causing damaged leaves to turn yellow and shrivel. If they gather on the young stems and flower stalks of seed vegetables, the flower stalks become twisted and deformed. The green peach aphid can also transmit viral diseases. The green peach aphid belongs to Homoptera, Aphididae. The wingless parthenogenetic female is about 2.6 mm long, with a green, yellow-green or cherry-red body, well-developed frontal tubercles that slant inward. The cornicles are relatively long, longer than the fifth antennal segment, dark at the tip, swollen in the middle and rear parts, and constricted at the end. The cauda is conical, with 3 pairs of hairs on both sides. The winged parthenogenetic female is about 2 mm long, with a black head and prominent frontal tubercles that slant inward. The compound eyes are reddish brown. The thorax is black, the abdomen green or yellow-green, with pale black markings on the dorsal surface. The cornicles and cauda are the same as those of the wingless female.

〔Living habits〕The green peach aphid occurs in all regions, with 10 to 40 generations a year varying by place. In the north it has more than 10 generations a year; in Shandong, Anhui and other places it has 24 to 28 generations, in Hunan 30 generations, and in Guangdong up to 40 generations. In winter in the north, most green peach aphids overwinter as fertilized eggs on peach branches or in leaf axils and buds, and some overwinter with autumn vegetables in vegetable cellars, or in winter spinach fields; in greenhouses and other protected areas they can reproduce and cause damage all year round. In the south, because temperatures are relatively high, they can reproduce and cause damage all year round on cruciferous vegetables, with no overwintering phenomenon. From March to April of the following year, the overwintering eggs begin to hatch. After reproducing for several generations on the overwintering host, winged aphids are produced and migrate to vegetable fields, first reproducing and causing damage on cruciferous seed vegetables, then spreading and migrating to solanaceous vegetables, legumes and other crops, and in mid-to-late October they migrate again to the overwintering host to overwinter. Aphids that overwinter as parthenogenetic females on autumn vegetables or in winter spinach fields can migrate directly to vegetable fields in early spring; this portion occurs early. In protected areas, especially in greenhouses, they can reproduce and cause damage throughout the year. The green peach aphid has a short generation time, strong reproductive capacity, and severe overlapping of generations. The green peach aphid has a strong attraction to yellow and orange-yellow, followed by green, and a negative response to silver-gray. Yellow sticky boards or yellow pans can be used to trap and kill aphids or to monitor and forecast aphid population dynamics, and silver-gray film can also be used to repel aphids and prevent aphids from transmitting viral diseases. The optimum temperature for green peach aphid development is about 24°C, and the relative humidity is 50%-80%. In addition, the occurrence of the green peach aphid is greatly affected by natural enemies, such as ladybugs, lacewings, hoverflies, aphidiine wasps, etc. If natural enemies are abundant in nature, they can control aphid damage.

〔Control measures〕(1) Take advantage of the aphid's attraction to yellow by placing yellow sticky boards in the field, which can attract large numbers of winged aphids; the control effect is even more pronounced in protected areas. (2) Chemical control. Spray with 50% pirimicarb wettable powder at 2000-3000 times dilution, or 40% or 50% dimethoate emulsifiable concentrate at 1000-1500 times dilution, or 2.5% deltamethrin emulsifiable concentrate, or 2.5% kung fu emulsifiable concentrate at 3000-4000 times dilution, or 25% beta-cypermethrin emulsifiable concentrate at 1500 times dilution, or 20% cypermethrin-malathion emulsifiable concentrate at 2000 times dilution, or 10% dichlorvos-cypermethrin emulsifiable concentrate at 4000 times dilution.