Control of leaf gall midge caused by insect pests of mango

This insect is a frequent and important pest and is distributed in Guangdong, Guangxi, Hainan, Yunnan, Fujian and other producing areas. The insect is a serious damage to shoot stage leaves, each leaf can have several or more than a dozen galls, which has a great impact on the quality of new shoots, leaving a large number of perforations in damaged leaves, affecting leaf photosynthesis efficiency, resulting in poor crown growth and affecting tree potential and yield.

Morphological characteristics of mango leaf gall midge (ErosomyiamangiferaeFelt), belonging to the family Diptera. Adult Cordyceps is yellow and its body length is about 1-1.2 mm. The egg is approximately oval, about 1 mm long and colorless. The larvae are shaped like maggots and yellow. The last instar larvae are about 2 mm long and 0.6 mm wide, with obvious body segments and slender sword bones. The pupa is short oval and yellow, the pupa is 1.4 mm long, and there is a yellowish-brown membrane capsule on the outside.

The occurrence regularity and habits of the insect are about 8 generations a year. After the middle of November, the larvae pupate at a depth of 3-5 cm in the topsoil over the winter, and the Eclosion is unearthed around the first ten days of April in the following year. The mating peak is from 9 to 10:00 in the evening, and the female lays eggs on the back of the tender leaves in the next morning. The female died 2-3 days after oviposition, and the male died the next day or the third day after mating. After hatching, the larvae bite through the epidermis of the tender leaves and drill into the leaves to feed on the mesophyll, causing scalding spots, forming small tumorous galls as the larvae grow up, there may be more than a dozen galls in one leaf, the tissue of the injured leaves is necrotic, and the larvae break in the center after leaving the galls, resulting in perforation and irregular reticular rupture of the seriously damaged leaves, and then the aged larvae enter the topsoil to pupate.

The prevention and cure method ① strengthens the fertilizer and water management, promotes the shoot to be neat, is advantageous to the shoot stage unified spraying to control insect pests. When the leaves of new shoots and tender leaves of ② draw out 3-5 cm, choose 20% fenpropathrin EC or 10% cypermethrin EC or 25% dimethoate EC 2000-3000 times, 40% dimethoate EC or 40% isocarbophos EC, 40.8% chlorpyrifos (Lesben) EC 1000-1500 times liquid foliar spray, application interval 7-10 days, each shoot period 2-3 times, apply evenly Spray the ground within the drip line of the tree crown in spring. ③ poisonous soil kills insects. Before the spring rain comes from February to March every year, it is recommended that every 666.7 square meters isomalidophos granules 4-5 kg plus fine sand or mud powder 20 kg, evenly spread on the soil surface within the crown drip line, and then covered with 2 cm thick mud powder, can kill larvae buried in the soil and adults that will be Eclosion unearthed in spring. At this time, the activity space is limited, the population density is low and the resistance is weak, so it is better to concentrate efforts on control. The duration is about 60 days.