admin

Received: 26th November 2020; Accepted: 20th December 2020

Abstract

Rice planthoppers have again attained a major pest status in this century causing enormous yield losses through direct feeding and transmission of pathogenic viruses. Consequently, there has been increased focus of research on their biology, genetics and molecular biology in search of alternative methods to manage them. This review highlights main findings of these studies to reveal how genetic plasticity of the brown planthopper (BPH) has equipped the species to fight back adversities and pose challenges for its effective management. Genome of BPH with size of 1141 Mb spread across 30 chromosomes is predicted to have 27,571 genes. Salivary glands, first line of offense, secrete proteins that trigger either susceptibility (ETS) or immunity (ETI) reaction in the host plant. Fat bodies, spread all over the body, are sites of primary lipid metabolism, endocrine regulation, systemic immunity, vitellogenesis, and housing of microbial symbionts. BPH harbours yeast like symbionts (YLS) in its fat bodies that play critical role in insect survival. BPH populations across Asia have acquired resistance against almost all classes of insecticides which has been attributed to neofunctionalization of duplicated P450 genes. So far about 40 major host plant resistance genes and 72 QTLs have been reported from cultivated rice and its wild relatives but BPH has ability to quickly evolve virulent populations. Role of cytochrome P450 enzymes and of symbiotic YLS in this ability has been shown. Several studies have focused on the reproductive physiology of BPH and identified key genes that can be target for RNAi mediated silencing as novel strategy for pest management. Several recent studies have also covered genetic and molecular basis of wing polymorphism and adaptation for long distance migration in this insect. Other recent studies on effect of climate change on BPH incidence and its genetic ability to adapt to the changes in the weather and climate have cautioned that this insect is likely to continue to be a major problem in days to come. On a larger perspective, this rapidly expanding knowledge is providing us with novel approaches and tools to contain the pest and stay a step ahead of it in the evolutionary race.