Identical threats of rice: Insights into biotypes of brown planthopper (Nilaparvata lugens stal)

By continuous feeding, insects tend to overcome the host resistance. As the plant resistance mechanism gets upgraded in due course of time, the monophagous insects co-evolve as a means of adaptation, which includes biotype formation. A biotype is morphologically identical to its original form, primarily based on the selection pressure exerted by the host. Brown Planthopper (BPH) is a major rice pest in Asia, which could able to cause 60 % of yield loss under severe pest outbreak. This Brown planthopper exhibits multiple biotypes distinguished by their ability to overcome specific host resistance genes. Four original biotypes have been identified, with biotypes 1 and 2 being prevalent in Southeast Asia and East Asia. Biotype 3 developed under laboratory conditions on resistant varieties while biotype 4 is native to the Indian Subcontinent. These biotypes differ in virulence, feeding behaviour and overcoming resistant genes in rice cultivars. Understanding the genetic basis of biotype differentiation and host resistance mechanisms is crucial for durable, broad-spectrum BPH resistance in rice. Though more than 46 resistance genes/QTLs have identifies so far, long-term management depends on combining genetic strategies such as gene pyramiding by utilizing multiple genes at a time along with regional monitoring of biotypes and area-wide IPM programs which can slow down the adaptation by the pest. These strategies balance resistance durability with lower pest selection pressure, for better pest management and increased rice yields.