Brown planthopper, Nilaparvata lugens (Stål.) is one of the most ruinous pest of rice in south-east Asia. This insect had the tendency to express differential reaction to resistant rice cultivars and various insecticide groups in different geographic locations. Therefore, genetic diversity among the N. lugens populations is required to be understood for their effective management. Hence, in the present study, genetic structure and genetic diversity of 22 N. lugens populations collected from 22 hotspot regions of India were studied with genomic simple sequence repeats (NlSSR) markers. Results revealed that mean genetic diversity was 0.399 and polymorphic information content (PIC) was 0.337 in the 30 selected SSR markers. Further, molecular variance (AMOVA) revealed only 2% variation among population and 98% within the populations. In cluster and population structure analysis, all the 22 population were sub-grouped into three groups. Interestingly, north and west Indian population showed high genetic similarity and assembled into one cluster in cluster analysis. The east and south Indian populations were evenly segregated into rest two clusters. Similarly, north and west Indian population again deemed to be occupied same compartment in Principal coordinate analysis (PCoA). This variation might be associated with the N. lugens migration due to wind movement of south-west monsoon in two branches viz. Arabian sea branch and Bay of Bengal branch. Present study provides the molecular evidence of population genetics of N. lugens in India and the information could be useful to devise the efficient management strategy against this pest in different rice ecosystem.
Okra, Abelmoschus esculentus (L.) Moench is a major vegetable crop grown in India. The crop is susceptible to various sucking insects and mite pests throughout the cropping period. The present field experiment was carried out to observe the incidence and correlation between weather parameters and sucking pests along with their natural enemies in okra (variety Arka Anamika) at Central Research Station, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha during summer 2021.The maximum population of two major sucking pests i.e., leafhopper and whitefly was observed at 22nd and 19th standard meteorological week (SMW), respectively where as the peak activity of aphid and two spotted spider mites were recorded at 21st SMW. Among the natural enemies, coccinellid and spiders were recorded and the highest activity was observed at 22nd SMW. The correlation studies revealed a significant positive correlation between minimum temperature (r= 0.577) and afternoon relative humidity (r= 0.618) with leafhopper population. Further, there was significant negative correlation between spider population and maximum temperature (r= -0.788) where as both morning and afternoon relative humidity (r= 0.677 and r= 746) had positive effect. In addition, there was significant positive correlation between the predators (coccinellid and spider) and prey (aphid and leafhopper) population. Therefore, from ecological point of view understanding the relationship between pest and natural enemies and their incidence is necessary to take timely pest management measures.
Evaluation of biophysical parameters of okra germplasm for resistance or susceptibility to jassids Amrasca biguttula biguttula (Ishida) was conducted at the All India Coordinated Research Project on Vegetable Crops, Odisha University of Agriculture and Technology, Bhubaneswar during kharif 2018 and summer 2019. The results revealed that the plant height, number of leaves, leaf area, leaf thickness, and trichome length and density of 50 okra germplasm varied from 73.45 to 129.93 cm, 10.50 to 24.00 leaves/ plant, 203.70 to 389.25 cm2, 0.40 to 0.96 mm, 0.38 to 0.96 mm and 3.50 to 10.25 trichomes/ cm2, respectively. The plant height, number of leaves and leaf area showed positive correlation with incidence, whereas leaf thickness, trichome length and trichome density exhibited negative correlation. The okra germplasm BBSR-37, BBSR-36 and BBSR-57 were found to be resistant, while Pusa Sawani, BBSR-53 and BBSR-18 were observed to be susceptible.
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