Orchid pest-- APHIS gossypii

Cotton aphid Aphis gossyPii Glover, also known as melon aphid, belongs to Homoptera, aphid family, commonly known as honey aphid, oil worm, oil sweat and so on. Cotton aphid (APHIS gossypii) is a worldwide pest, which is also distributed all over China, and the damage degree varies from place to place. The occurrence is generally serious in the north, followed by the Yangtze River basin, and it is also very serious in the dry years in the south. There are many kinds of hosts, such as Fusang, Luo Kui, hibiscus, orchid, pomegranate, bauhinia, plum and plum, etc. The adult nymphs of APHIS gossypii concentrated on tender shoots, buds and leaf back, absorbed juice and wrinkled the back of leaves to affect flowering.

Morphological characteristics:

Wingless viviparous female aphids: body length 1.5~1.8mm, yellowish green in summer, dark green to bluish black in spring, mottled back, all covered with wax powder, 6 antennae, only one sensory circle at the end of the fifth segment, short abdominal tube, cylindrical, broad base and papillary tail.

Winged fetal female aphids: 1.2~1.7mm, yellow in summer, or green to dark green in summer, blue-black in autumn, 3-4 pairs of black spots on both sides of the back, 6 antennae, longer than the body, 4-10 sensory circles in the third segment, usually 6-7, almost in a row, 2 sensory circles in the fourth section, a sensory circle near the end of the fifth section, a cylindrical abdominal tube, black, with tile patterns on the surface.

Winged viviparous male aphid: about 1.4mm long, grayish black head, reddish brown compound eyes, 6 antennae, sensory circle

Born in verses 3, 4 and 5.

Eggs: oval, long O.5~0.6mm, orange at first birth, then dark brown, pitch black after 6 days.

Occurrence regularity: more than 20 generations a year, the eggs overwintered on branches such as mulberry, hibiscus and pomegranate, and hatched at 11 ℃. Winged migration aphids were first harmed by overwintering hosts. Winged migration aphids began to harm flowers from March to April. Winged migration aphids flew to hibiscus and other overwintering hosts in September and October to continue to reproduce. Winged male aphids and wingless female aphids were produced when the weather was cold in November.

Cotton aphids are generally viviparous and only produce egg-type female aphids before overwintering. The migration of aphids depends not only on the migration of winged aphids, but also on their creeping ability. The optimum temperature for the reproduction of cotton aphid is 16-22 degrees, the temperature is above 25-27 degrees, and the relative humidity is above 75%. When the climate is suitable, the cotton aphid can reproduce in 4-5 days, and the reproduction capacity is large, and each female aphid can produce 5 small aphids on average. When the weather is cold, it takes 19 days to reproduce, and continuous torrential rains can significantly reduce the number of cotton aphids.

Prevention and control methods:

1. Protection and utilization of natural enemies, ladybugs, lacewings and other natural enemies have been released after artificial breeding.

2. Remove the overwintering hosts around the orchid nursery, such as chrysanthemums, and destroy the overwintering eggs.

3.3% pyrethrin, 2.5% rotenin, 800mm 1200 times, 20% fenvalerate EC 3000 times

2.5% permethrin EC 2000-3000 times. 40% dimethoate EC 1000 liquid spray.

Liu Zhongjian