Screening of Rapeseed-mustard Genotypes and Eco-friendly Management of Mustard Aphid, Lipaphis erysimi (Kalt.).
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Date
2022
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Dr.RPCAU, Pusa
Abstract
The current investigations were conducted on “Screening of Rapeseed-mustard genotypes and eco-friendly management against mustard aphid, Lipaphis erysimi (Kalt.)” during 2019-2020 & 2020-21. The surveys conducted during the year 2020 across India, revealed that Lipaphis erysimi pseudobrassicae was present in all the 16 locations surveyed belonging to 13 states and one Union Territory at over altitude ranging from 40.42 m (Dariapur) to 980.80 m (Barapani). The selective RAPD primers viz., OPA-02, OPA-04, F2 and SSR primers viz., ApH04M, Ap-01 and ApH08M were considered as informative for genetic diversity analysis based on polymorphic band percentage (>70), higher PIC, EMR, MI and RP. DNA barcoding of 16 locations with universal primer (LCO1490- Forward and RHCO2- Reverse) employed were amplified at 657 bp of mtCOI gene in Lipaphis erysimi pseudobrassicae. The phylogenetic tree showed the clustering of all 16 locations with L. e. pseudobrassicae reference sequence. Among 16 locations, Jorhat of North-Eastern India was found to be highly diverged with higher branch distance (0.13) in the phylogenetic tree and higher dissimilarity of 30.0 and 31.0 % in RAPD and SSR dendrograms respectively. The association of bacterial endosymbionts with L. e. pseudobrassicae showed that Buchnera sp, a primary endosymbiont was found in all the 16 locations. Whereas in secondary endosymbionts, Wolbachia sp, Rickettsia sp, and Hamiltonella sp dominated the most with 81.25 % and Cardinium sp liberated with 31.25 %. Among all 16 locations, Jodhpur and Ranchi had a 100 % incidence of endosymbionts and lower incidence was found in Ludhiana, Raipur, Dharwad, Alipur Bihta, Delhi, Jorhat (42.85 %). The inspections on population of alate mustard aphids and natural enemies i.e., adult coccinellids, syrphids and parasitoids in relation to weather parameters revealed their peak on 8th SMW (157.1, 6.48, 5.63, 14.62/ 4 traps) respectively and shown strong positive correlation with maximum temperature (0.445, 0.608*, 0.595*, 0.618*) and sunshine hrs (0.602*, 0.654*, 0.633*. 0.662*) respectively. Different Rapeseed-mustard genotypes were screened against mustard aphid resulting in identification of six promising genotypes among which, genotype RTM 314 had shown low AII (1.3), ADI (1.0) and ARI (1.15). The biochemical analysis also revealed the highest glucosinolates (109.87 µmole/g) and phenols (6.51 mg/g) content in RTM 314. Further, GC-MS analysis indicated the existence of biologically active compounds like 2-(hydroxymethyl)-2-nitro-1,3-Propanediol; 5-(Methylsulfinyl)pentanenitrile and 1-Isothiocyanato-4-(methylsulfinyl)butane only in RTM 314 which could be the reason for resistance against mustard aphid. Among different intercrop combinations, mustard + wheat (3:1) followed by mustard + barley (3:1) have recorded lowest aphid population (41.46, 42.79/ top 10 cm inflorescence of 10 plants) respectively and highest population of coccinellids (8.29, 7.76/ 10 plants), syrphids (6.57, 6.35/ 10 plants), parasitoids (14.01, 13.34/ 10 plants) and spiders (4.39, 4.21/ 10 plants) with superior yield (1213, 1201 kg/ha) respectively. The efficacy of various botanicals was also evaluated against mustard aphid and its natural enemies. Among the botanicals tested on mustard aphid, the % reduction of mustard aphid population over untreated control following the first and the second spray was the highest in Neem Seed Kernel Extract (NSKE) @ 5% (70.69, 87.97 %) followed by Yam Bean Seed Extract (YBSE) @ 5% (66.58, 86.06 %) and Bhang Leaf Extract (BLE) @ 5% (64.25, 84.56 %) respectively besides with higher population of natural enemies. However, based on B: C ratio, BLE @ 5% with 6.86:1 was found to be better followed by NSKE @ 5% (3.61:1) and YBSE @ 5% (3.31:1).