Harm and Control of Liriomyza huidobrensis in Rice seed production

Rice stalk miner (ChloropsoryzaeMatsumura) is mainly distributed in Heilongjiang, Zhejiang, Jiangxi, Hunan, Hubei, Guangdong, Guangxi, Yunnan, Guizhou, Sichuan, Chongqing and other provinces in China. In recent years, it has become one of the main pests in rice production in hilly and mountainous areas of Chongqing, and the loss caused by it has exceeded that of some important pests such as borer. In rice seed production, the occurrence of Liriomyza huidobrensis seriously affected the development process of rice, which led to poor meeting of parents at this flowering stage and affected the yield of seed production. Through experimental observation and recording, the author systematically introduced the biological characteristics of Liriomyza huidobrensis and its occurrence, harm and control techniques in rice seed production for reference.

1 morphological characteristics and main living habits of Liriomyza huidobrensis

1.1.Morphology characteristics of Liriomyza huidobrensis belongs to Diptera Liriomyza huidobrensis. The adults have long 2~3mm, wingspan 5~6mm and bright yellow body. There is a diamond-shaped black spot on the top of the head; the compound eyes are large and dark brown; there are three dark brown longitudinal stripes on the back of the chest and a black horizontal band at the junction of the abdominal and dorsal segments. There are 1 black spots on each side of the back of the first section, and the ventral surface of the body is light yellow; wings transparent, wing veins brown; feet yellowish brown, dark black at the end of the foot; oval, white, long 0.7~1mm The larva is maggot-shaped, the body is 5~6mm when mature, slightly fusiform, 11 nodes, milky white or yellow, the mouth hook is light black, the tail end is 2-forked; the pupa is long 6mm, yellowish brown, with black spots on the upper part, and the tail end is also divided into 2 forks.

1.2 Life habits of Liriomyza huidobrensis in Chongqing, there are mainly two generations in a year, and the occurrence of each generation is extremely irregular. The overwintering larvae overwintered on weeds such as wheat grain, wandering grass, Kentucky bluegrass and paspalum grass. The overwintering larvae reached the peak period of pupation from late March to late April, and the first oviposition period was from late April to early May. The adults mostly laid eggs on the back of the leaves and laid eggs scattered. The newly hatched larvae moved downward along the back of the leaves by means of dew, mainly harming the heart leaves of rice seed production seedlings, the second spawning period was from mid-late June to late July, and mainly damaged the young panicles in the young panicle differentiation stage after hatching. After one month of larval stage and maturity, most of each generation crawls to the inside of the plant leaf sheath to pupate, generally 1 sheath 1 to 2 pupae, then Eclosion into adults, migrates to overwintering host plants to lay eggs, mostly overwintering as larvae. It generally occurs above 300m above sea level, and the damage is aggravated with the increase of altitude, and the occurrence time is slightly delayed.

2 occurrence and harm of Liriomyza huidobrensis in rice seed production

2.1 the occurrence of Liriomyza huidobrensis in rice seed production is more common in rice seed production than in hybrid rice. In the process of rice seed production, in order to make the male parent grow well and have more tillers and apply a large amount of nitrogen fertilizer, the growth is relatively light green, and the population density of the female parent is also larger, so that the resistance is weakened, so it is more vulnerable to the harm of Liriomyza huidobrensis; on the other hand, the resistance of medium hybrid rice is generally stronger than that of conventional varieties (including parents and female parents), and the planting density is relatively rare, which is not conducive to the growth of diseases and insect pests. For example, in 2005, in the seed production field of Shituo Town, Fuling District, Chongqing, which is 300m in Haipu, it was found that on May 2, the injured plant rate of male parent seedlings without pesticide control was 35%-40%, while that of adjacent medium hybrid rice seedlings under the same management was 10%-20%. Seed production was conducted in Tongle Township, Fuling District, Chongqing from 2003 to 2005. It was found that the injured plant rate of male parent seedlings without pesticide control was 50%-70%, while that of adjacent medium hybrid rice was 30%-40%. The harm of rice stalk leafminer in the young panicle differentiation stage of rice in the seed production area is the same as that of medium hybrid rice. If the control is not effective, the damaged plant rate can reach about 70%, resulting in a yield loss of about 20%.

2.2 occurrence time and harmful symptoms of Liriomyza huidobrensis in seed production field, Liriomyza huidobrensis was mainly harmful to the parents of early sowing in the seedling stage of rice seedlings, mainly male parents, Ⅱ ~ 32A and other parents with long growth period and early sowing, and the occurrence was slightly delayed with the increase of altitude. It was found that the oviposition period of adults was about 300m above sea level, and the first occurrence of larvae could be seen at the end of April after egg hatching, and the first occurrence of larvae could be seen at the beginning of May after egg hatching. It is thought that the seedlings in the seedling field are mainly harmful to the seedlings with 3 to 8 leaves, such as eating heart leaves, the damaged leaves are in the shape of row holes or filaments, the growth of seedlings is slow or even stagnant, which significantly prolongs the growth period of the injured parents, resulting in a serious lack of florescence. The second damage peak was mainly in the middle and late June, when the rice seed production entered the young panicle differentiation stage, and the larvae were harmed at the growth point. After the first half of the young panicle was fed, the spikelets degenerated and could not form normal grains, and after heading, there were only a small amount of degenerated white branches or abnormal spikelets in the upper part of the panicle, and the panicle did not hook up after grain filling, which caused serious loss to the yield of rice seed production.

3 control of Liriomyza huidobrensis

3.1 Agricultural control of rice stalk Liriomyza huidobrensis combined with fertilizer accumulation in winter and spring to remove weeds on the edge of the field, ditch and hillside, and reduce the source of overwintering insects.

3.2.The period of ① control of Liriomyza huidobrensis. According to the occurrence period of Liriomyza huidobrensis in rice seed production, the whole process of rice seed production should focus on 4 times of special control in 2 periods. The first period is the seedling stage, the first time grasps the larva hatching stage control (the end of April), the second time grasps the larval harm initial control (early May), this stage mainly kills the eggs and larvae, the second period is the young panicle differentiation stage, the first time grasps the young panicle differentiation initial control (mid-June), the second time grasps the control of young panicle differentiation stage 2-3 (late June), mainly to protect the panicle from damage. ② control agents. The generations of damage caused by the larvae of Liriomyza huidobrensis in the field overlap, which leads to the difficulty of control, so the pesticides with strong internal absorption and long effective period should be selected in the use of chemicals. The ideal control effect can be achieved by spraying 5% Regent 600~750mL/ ha or 2% BBG 750 ~ 1050ml/ ha to water 750~900kg/ ha. In rice seed production, chemical control is given priority to, supplemented by agricultural control.