What are the specific insecticides for the small brown planthopper? Scientific application gives good results
The small brown planthopper (Laodelphax striatellus) is widely distributed in East Asia, Southeast Asia, Europe and North Africa, and within China it is found throughout the country, with more in the Yangtze River basin and northern rice-growing areas. So what are the specific insecticides for the small brown planthopper? What are good control methods?
1. Specific insecticides for the small brown planthopper
For control agents, single products such as pymetrozine, nitenpyram, etofenprox and thiamethoxam and their mixtures can be selected; attention should be paid to alternating the insecticides to delay the development of resistance in the small brown planthopper.
The rice seedling stage is the key period for preventing and controlling the damage of the small brown planthopper, and prevention and control work must be done in time. In terms of control methods, for seedling fields not covered with insect-proof nets and with high insect numbers, apply insecticide in time. Before transplanting the seedlings, use the rice planthopper product from the Rice Heavy Weapon series, so as to transplant with the insecticide applied. For fields with high insect numbers that have already been transplanted (including direct-seeded rice fields), apply insecticide immediately after the seedlings turn green or after the seedlings show green.
2. Occurrence pattern
Except in southern rice areas where there is no overwintering phenomenon, the small brown planthopper mostly overwinters as 3rd to 5th instar nymphs in wheat fields, green manure fields, at the roots of weeds, under fallen leaves and in soil cracks. When the temperature is above 5°C it can climb onto the host to feed, and in spring when the average temperature is around 10°C it begins to emerge. When the temperature rises, the overwintering nymphs seek suitable nearby places to survive, generally migrating to wheat fields to cause damage. The adults emerging from the overwintering generation are generally mainly brachypterous (short-winged), living on weeds or in wheat fields, and the first-generation nymphs they produce form the peak of insect numbers; the small number of macropterous (long-winged) adults emerging from the overwintering generation may migrate to double-season early rice seedling fields to cause damage.
3. Living habits
The population dynamics of the small brown planthopper are mainly related to factors such as the farming and cultivation system, climate, natural enemies, host food conditions and artificial control. In Jiangsu Province, the small brown planthopper usually has 5 to 6 generations, mainly overwintering as 3rd to 4th instar diapause nymphs on wheat and weeds; after spring it reproduces one generation on wheat, and from late May to mid-June is the peak emergence period of the first-generation adults. At this time the small brown planthopper migrates in large numbers from wheat fields and weeds to rice, transmitting the virus and forming the first virus-transmission peak in seedling fields and early-planted fields, and in late June the first peak of disease symptoms appears in the field.
In mid-to-late June, the hatched nymphs of the second generation of the small brown planthopper pierce and suck to transmit the virus in the main rice fields, forming the second virus-transmission peak, and in mid-to-late July the second peak of disease symptoms appears; when the climate is suitable, the third generation of the small brown planthopper will form the third and fourth peaks of virus-transmission damage, and 2 to 4 peaks of symptoms can appear in the field in a normal year; afterwards, the small brown planthopper oversummers in extremely low numbers on hosts such as gramineous weeds and rice, and high temperatures can cause diapause in the small brown planthopper; when the weather turns cool in late September it reproduces one more generation (the fifth generation) to overwinter, and in autumn, as the rice is harvested, it moves nearby to field-edge weeds or interplanted wheat seedlings to overwinter.
The control of the small brown planthopper can also be carried out through various methods such as biological control and chemical control, and it is best to choose varieties with relatively strong insect resistance.