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Nilaparvata lugens, the brown planthopper (BPH), is a serious pest species. BPHs cause significant damage to rice plants in Korea as well as other countries in East and Southeast Asia. As BPHs cannot survive winter in Korea, they annually migrate into Korea from foreign countries. The BPHs found in Korea are believed to originate from China, but most BPHs in China are also known to originate from Southeast Asia. To understand the origin of Korean BPHs, we conducted a genotyping‐by‐sequencing (GBS) study. We sampled BPHs from five locations in Korea and five countries in Southeast Asia and analyzed the GBS and sequencing results using various methods based on the f statistics and admixture graph analyses. We confirmed that the domestic BPHs shared a greater genetic drift than the BPHs from Southeast Asian populations over several years, implying that a continuous genetic substratum of Korea exists. This genetic substratum is genetically closer to BPHs from the southern part (Thailand and Cambodia) of Southeast Asia than to BPHs from the northern part (Bhutan, Myanmar and Laos) of Southeast Asia. In addition, direct gene flows from Southeast Asia seem possible, so Korea is considered a hotspot where diverse BPH populations mix. Therefore, the origin of Korean BPHs extends beyond China and as far as southern Southeast Asia. This result will help to understand and control the population dynamics of the Korean BPH population. [ABSTRACT FROM AUTHOR]

Brown planthopper, Nilaparvata lugens (Stål) is one of the most destructive pests of rice in Southeast Asia. It expresses a differential reaction to resistant rice cultivars and various insecticide groups in different geographic locations. Therefore, genetic diversity among N. lugens populations must be understood for their effective management. Hence, in the present study, the genetic structure and diversity of 22 N. lugens populations collected from 22 hotspot regions of India were analysed using with genomic simple sequence repeat (SSR) markers. Results revealed that the mean genetic diversity was 0.399 and polymorphic information content was 0.337 in the 30 selected SSR markers. Further, molecular variance revealed only a 2% variation among the populations and 98% within a population. In cluster and population structure analysis, all 22 populations were sub-grouped into three groups. Interestingly, the North and West Indian populations showed high genetic similarity and assembled into one cluster in cluster analysis. The East and South Indian populations were evenly segregated into the remaining two clusters. Similarly, the North and West Indian populations shared the same compartment in principal coordinate analysis. This variation might be associated with the N. lugens migration due to wind movement of the southwest monsoon in two branches, viz. Arabian Sea branch and Bay of Bengal branch. The present study provides molecular evidence for genetic variation among different populations of N. lugens in India. The information could be helpful to devise an efficient management strategy against this pest in different rice ecosystems. [ABSTRACT FROM AUTHOR]

Genetic resistance in rice through native traits is an important tactic to manage Brown planthopper (BPH), Nilaparvata lugens Staal (Homoptera: Delphacidae) which is one of the most dreaded pests in the farmer's field causing serious crop losses. Many sources of resistance, both from cultivated and wild accessions, are known with almost 36 resistance genes mapped to different chromosomes through phenotypic and genotypic selections. A majority of resistance genes identified are effective for BPH biotypes prevailing in Southeast Asia and China. For South Asia, very few BPH resistance genes are effective but without their utilization for the development of commercial hybrids and varieties. A new source of resistance HSPP 6417 has been identified in the present paper, which displayed resistance to 11 populations of BPH collected from different rice ecologies of India. The new source HSPP 6417 had an adverse effect on the population dynamics of BPH by inhibiting the population build-up on the plants. The resistance of HSPP 6417 was equivalent to the only source of resistance in India, G7253 used to develop a commercial rice hybrid AZ8433 DT. On crossing HSPP 6417 with other prolific restorer lines of the commercial hybrids, the major genes were found to control its modes of inheritance. Field trials with F4 generation revealed that resistance was stable with good agronomic performance under infestations. The implications of using such a source of resistance for developing BPH resistant hybrids are discussed in the paper. [ABSTRACT FROM AUTHOR]

In this paper, we studied the brown planthopper (BPH) infestation on rice under the effects of monsoon using a two-time scales stage-structured predator–prey model. We divided the BPH population into two distinct stages, mature and juvenile, owing to the significant biological differences between the two. We considered a heterogeneous environment composed of two adjacent rice fields. Using the two-time scales, we reduced the model into an aggregated model with smaller dimensions and topological equivalent. The positivity and boundedness of the model's solution were established. We conducted the dynamical analysis of the BPH–rice ecosystem through the local and global stability of the model's equilibria. Moreover, the effects of rice fields area and monsoon were analyzed using Hopf bifurcation theory. We performed numerical simulations to illustrate the theoretical results. Finally, we provided some emergence discussions from the ecological perspective to give useful information for preventing and managing BPH on rice. • Brown Planthopper causes "Hopperburn" outbreaks in rice fields in Southeast Asia. • A predator–prey model for the Brown Planthopper–rice system under the monsoon factor is proposed. • The model considered a heterogeneous environment, stage-structured population, and two-time scales. • The system was evaluated using stability analysis and Hopf bifurcation. • Numerical simulations were presented to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]