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The war on rice: How can we combat the invasion of brown migratory locusts with resistant varieties?
As global concerns about food security escalate, the brown migratory locust (Nilaparvata lugens) has become one of the main pests affecting rice production. This pest not only causes direct plant damage during the farming cycle, but also carries a variety of pathogens, further threatening the health and yield of rice. How to effectively use resistant varieties to resist the invasion of this pest has become an important topic in the current agricultural science and technology community.
Biological characteristics of brown migratory locust
The brown migratory locust is a dimorphic insect that is morphologically divided into two categories: the "winged type" that can fly and the "short-winged type" that cannot fly. The winged form is mainly responsible for migration and colonization of new places, while the short-winged form mostly exists in stable environments. Migratory locusts usually mate in rice fields and lay eggs in leaf sheaths, which take about six to nine days to hatch. Newly hatched nymphs are distinguished by their white cottony appearance that quickly turns purple-brown and feed on plant sap.
Damage to rice
Brown migratory locusts can cause severe damage to rice at all growth stages. Both larvae and adults suck sap from the base of the seedlings, causing the plants to quickly turn yellow and wither. In the early stages of infection, circular yellow spots appear in the rice fields, which then turn into brown "locust burn". This phenomenon not only affects the growth of crops, but also causes up to 60% yield loss.
Natural enemies of brown migratory locusts
Although the brown migratory locust is at the top of the food chain in the ecosystem, it also has its natural enemies, such as wolf spiders and certain spiders. In some cases, brown migratory locusts lay eggs in rice seedling beds before transplanting, so they also enter the field survey through this route. It should be noted that some pesticides will indirectly increase the reproduction rate of locusts, thereby triggering the recurrence of pests, which shows the importance of ecological balance in the control of brown migratory locusts.
Management and Control Strategy
The prevention and control of brown migratory locusts requires comprehensive considerations. Excessive use of nitrogen fertilizers and pesticides can encourage the reproduction of migratory locusts and reduce the number of natural enemies. For this reason, the integrated pest management (IPM) strategy becomes a top priority. For example, in 2011, the Thai government announced a measure to combat an outbreak of brown migratory locusts, restricting the use of certain pesticides that cause the outbreak. The International Rice Research Institute (IRRI) also provided relevant management advice.
The importance of resistant varieties
Resistant varieties such as IR64 play an indispensable role in preventing outbreaks of brown migratory locusts. Especially in areas where pesticide use is low, high levels of resistance are often not necessary. Through chemical mutation, the resistance of rice to brown migratory locust can be significantly increased or decreased. In addition, the new research also aims to develop control technologies for brown migratory locust genes to increase the expression of specific genes in rice.
Impacts of climate change
According to research, brown migratory locust nymphs are approaching the maximum temperature range they can tolerate. This means that in tropical regions, with climate change and frequent occurrence of extreme high temperatures, the survival and distribution of brown migratory locusts will be restricted, which will have a certain impact on the future production of rice.
Can we find better solutions in agricultural technology to fight nature's enemies and ensure our food security?
