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Plant beneficial rhizobacteria (PBR) is a group of naturally occurring rhizospheric microbes that enhance nutrient availability and induce biotic and abiotic stress tolerance through a wide array of mechanisms to enhance agricultural sustainability. Application of PBR has the potential to reduce worldwide requirement of agricultural chemicals and improve agro-ecological sustainability. The PBR exert their beneficial effects in three major ways; (1) fix atmospheric nitrogen and synthesize specific compounds to promote plant growth, (2) solubilize essential mineral nutrients in soils for plant uptake, and (3) produce antimicrobial substances and induce systemic resistance in host plants to protect them from biotic and abiotic stresses. Application of PBR as suitable inoculants appears to be a viable alternative technology to synthetic fertilizers and pesticides. Furthermore, PBR enhance nutrient and water use efficiency, influence dynamics of mineral recycling, and tolerance of plants to other environmental stresses by improving health of soils. This report provides comprehensive reviews and discusses beneficial effects of PBR on plant and soil health. Considering their multitude of functions to improve plant and soil health, we propose to call the plant growth-promoting bacteria (PGPR) as PBR.

Abstract The Himalayan mountains are early indicators of climate change, wherein slight changes in climate can lead to a drastic variation in faunal diversity, distribution, invasion of fauna into higher altitudes, rapid population growth, shortening of life cycle and increased number of overwintering species. The insects best represent the faunal diversity. In recent years, due to variation in pattern of rainfall and temperature regimes, several insect pests have moved northwards and are posing great threat to hill agriculture. Few among them are greenhouse whiteflies, thrips and mites in protected cultivation system; blister beetles on flowers of cereals, pulses and oilseeds; invasive insect pests like fall armyworm of maize and tomato pin worm and sporadic pests like grasshoppers that are reaching a status of major key pest in various crops. Keeping in mind the phenomenon of climate change and associated changes in pest population, the present article focuses on emerging insect pest problems in cereals, millets, pulses, oilseeds and vegetables of Indian Himalayas, along with their changing population density with respect to different climatic parameters, the per cent increase in the pest damage over the years and their potential of gaining the status of major pests in near future and causing huge economic losses to hill agriculture.

Background The inadvertent observation of a substantial population reduction of greenhouse whiteflies infecting Salvia divinorum plants grown in a polyhouse sparked a flurry of inquiries on the cause of the population decline. The entomopathogenic fungus (EPF) ( Alternaria alternata strain VLH1) infecting greenhouse whitefly on S. divinorum plants was isolated and morphologically and molecularly characterised using multilocus sequence typing. Results The fungus was found to be highly virulent against sucking pests; with LC 50 values ranging from 1.7 × 10 4 to 2.5 × 10 6 spores per ml for the Mustard aphid ( Lipaphis erysimi Kaltenbach) and soybean sucking bug ( Chauliops choprai Sweet and Schaeffer), respectively. In the lepidopteran larvae treated with a concentration of 3 × 10 5 spores per ml, the fungus induced developmental abnormalities such as aberrant larval to pupal moulting, defective pupae, and deformed adults. Pathogenicity studies on the two beneficial insects ( Coccinella septempunctata (Linn.) and Apis mellifera L.) and 11 host plants revealed no disease signs, indicating that it is safe for use in pest management in hill agriculture. The chitinolytic activity of the fungus and its crude protein extracts was reported in studies conducted against target insect pests, with the highest chitinase enzyme production (117.7 U/ml) on the fourth day of inoculation. Furthermore, over a 96-h period, third instar Helicoverpa armigera (Hubn.) larvae fed on a protein fraction-amended artificial diet showed a significant decrease in nutritional physiology indices such as relative growth rate, relative consumption rate, efficiency of ingested food conversion, efficiency of digested food conversion, and approximate digestibility. Moreover, the polyhouse and open-field studies against two sucking pests; Myzus persicae (Sulz.) infesting capsicum in polyhouse and L. erysimi infesting Indian rapeseed in open-field conditions showed, 81.14% and 63.14% mortality rates, respectively, at 3 × 10 7 spore/ml concentration. Conclusions Entomopathogenic fungus (EPF) was reported to be an effective biocontrol agent, which caused direct mortality in sucking pests to developmental abnormalities in lepidopteran insects. Despite positive findings in in vitro and in vivo bioassay investigations against various insect pests, the fungus still has to be inspected before it can be used on a broad scale for biological pest management.

Although eggplant is self-fertile and self-compatible crop, it needs assistance of insects for buzz pollination. In the present study, floral biology of “Shyamili” variety was examined and the flowers were classified into three types, wherein, 62.63 ± 5.53% of the flowers were true flowers with long style, followed by rudimentary flowers with short style (24.74 ± 2.32%) and flowers with medium style (12.26 ± 0.97%). The optimum time period for stigma receptivity and pollen germination was recorded between 8.30 and 10.30 h, during which the activity of insect pollinators was at peak. A total of 29 insect species visiting eggplant flowers and the pollination behaviour of three insect pollinators ( Bombus haemorrhodalis, Apis cerana indica and Apis mellifera ) actively foraging on eggplant flowers was analysed. B . haemorrhodalis spent significantly higher amount of time per flower (34.33 ± 4.54 s), whereas, A. mellifera was swift flyer and visited significantly higher number of flowers per unit time (6.67 ± 1.03). In case of yield-related parameters, the flowers pollinated by interaction of two pollinators ( A. c. indica  +  B. haemorrhodalis ) recorded the best quality fruit (fruit length, girth and weight), yield per unit area and per cent yield increase over closed control. Moreover, artificial introduction of insect pollinators shortened the crop cultivation period by reducing the time required for fruit set and final harvest. Further studies are required to utilise both domestic ATED and wild bees simultaneously for commercial eggplant production and ecological engineering of the fields to create a suitable microclimate for survival and reproduction of wild bees.

Bacillus thuringiensis (Bt) is a ubiquitous pathogenic bacterium exploited worldwide in successful insect pest management programs. The present study aimed at resolving the diversity status and genetic structure of Bt isolates collected from unique and native ecological niche, north-western Indian Himalayas. Forty five Bacillus thuringiensis (Bt) isolates native to Uttarakhand, India were analyzed for their genetic diversity using Arbitrary Primed-Polymerase Chain Reaction (AP-PCR) patterns (ERIC1, ERIC2, BOX and GTG) and gyrase B (gyrB) sequences. Amongst the AP-PCR patterns, ERIC and BOX primers clearly indicated the genetic inconsistency of Bt by differentiating low and high hill isolates with unique banding pattern. Adendrogram generated showed fastidious clustering with coexistence of attitudinally related strains, indicating the genetic relatedness with respect to geographical proximity. The gyrB (285 bp) dependent phylogeny of seven selected isolates revealed their genetic proximitywith different serovars. The present study demonstrates that ERIC and BOX-PCRcan be used in establishment of geographical variation and gryB in phylogenetic relatedness with serovars. Genetic relatedness between Bt isolateswasfoundtobeafunctionofgeographical proximity.

Background Rugose spiraling whitefly (RSW), a native Central America species, was first reported in India during 2016. Since then, the observed rapid geographical distribution and consistent incidence over the years gave the insect, a key pest status on oil palm. Being an alien pest and oil palm being a perennial crop, a microbial entomopathogenic fungi (EPF) can only tackle the pest in ecofriendly and sustainable manner. In view of this, the present study was conducted to isolate EPF against RSW in soils of oil palm plantations using a custom developed insect baiting using soil solution technique. Results The present study led to isolation of a potential Aspergillus sp. R55. The isolate, R55, is highly virulent against adult and nymphal stages of RSW with LT 50 of 1.5 and 2.04 days at 10 6 conidia/ml, respectively. However, egg stage showed no mortality even at the highest concentration tested (10 8 conidia/ml). A two-year multilocational field evaluation of R55 in three plantations showed an average pest reduction of 61.98 and 94.44%, by 10 and 15 days after treatment, respectively. Moreover, the R55 isolate conidia showed thermal stability and survival up to 50 °C after 1 h of exposure. Safety studies of the isolate on oil palm pollinating weevil showed no negative impact on weevil emergence when inflorescence was treated. Conclusion The biosafety attributes to oil palm pollinating weevil and field virulence of R55 designate the isolate as a potential biocontrol agent against RSW infesting oil palm. However, by being an Aspergillus sp. further environmental safety studies are under progress.

Abstract Cabbage is a cross-pollinated crop because of sporophytic self-incompatibility, and honey bees play an important role in its pollination. Though Asian honey bees, Apis cerana F., are used in pollination of cabbage, the rate of visitation, behavior, pollinator efficacy, and impact on seed-set are to be determined. Apis cerana occupy a share of 19.18% of all the flower visitors of cabbage in natural habitat of North Western Indian Himalayas. Pollination behavior in terms of peak activity, flowers processed per unit time, time spent per flower, and time spent in search of flowers are studied separately for both pollen and nectar foragers. Pollinator effectiveness as measured by seed set in flowers excluded from bee visitation, single bee visit, and unrestricted pollinator visits was 0.11. Studies on the impact of A. cerana bee pollination in cabbage seed production revealed an increase of 17.28% in siliqua per panicle, with 26.11% increase in seed yield. For assessing the requirement of A. cerana to pollinate one hectare of cabbage, flower availability and the speed with which the pollen and nectar foragers process the flowers are taken into consideration. A forager is estimated to pollinate 4,780 flowers a day, but cabbage flower requires 9.09 visits of A. cerana for optimum seed set. Thus, a maximum of 4,999 bee foragers or 8.33 colonies are needed to effectively pollinate 1 ha of cabbage. Though A. cerana is a good pollinator, our findings suggest that it is not an ideal pollinator of cabbage.

The gram pod borer, Helicoverpa armigera (Hübner) is the insect pest of global agricultural importance due to its wide host range and cosmopolitan distribution, which is supported by a strong genetic base. This paper presents genetic diversity of the pest population feeding on different hosts (inter-host) and geographic locations (inter-location) in Uttarakhand Himalayas, India and their micro-evolutionary consequences. A total of 21 inter-host and 17 inter-location populations were studied using both nuclear (SSR markers i.e., 1st tier) and mitochondrial genes (cytochrome b i.e., 2nd tier). In case of inter-host populations, grouping was observed in relation to crop season (Kharif and Rabi), sequential growing of the crops and association of crops with weeds and concurrence of crop growth stages. Interestingly, in both the nuclear and mitogenome analysis, the wheat population stood separate as a major cluster, which might be due to its adaptation towards the crop in recent past in the region. Although there is a differential grouping in SSR and cytb based clustering in inter-location populations, high altitude populations stand separate. The study illustrates ecological and evolutionary driven behavioural adaptations in H. armigera populations in Uttarakhand Himalayan population, India.

An investigation was conducted to isolate, identify and molecularly characterize the chitinase-producing bacterial isolates from the guts of four pleurostict scarab beetle larvae [one species belonging to subfamily Rutelinae ( Anomala bengalensis ) and three species belonging to subfamily Melolonthinae ( Brahmina coriacea, Holotrichia setticollis and Holotrichia longipennis )] through 16 S rRNA sequencing. A total of 74 chitinase-producing bacterial strains were isolated from different gut compartments of selected species; of which 20 bacterial isolates recorded a clear halo zone of ≥ 5 mm (diameter) around the bacterial colony indicating chitinase activity. These 20 chitinase-producing bacteria were selected and sequenced for the 16 S rRNA gene. Maximum chitinase-producing bacteria were isolated from the fermentation chamber of all the selected scarab beetle larvae. The chitinase-producing bacterial community was represented by only two phyla i.e., Firmicutes and Actinobacteria. Bacillus was the most dominant group with 17 isolates. In addition to this, the insecticidal properties of chitinase-producing bacterial isolates were evaluated against mustard aphid ( Lipaphis erysimi ). Maximum per cent mortality was recorded by Bacillus licheniformis strain CHG3FC1 i.e., 30.00 ± 10.00% 72 h after treatment. Thus, the experiment proved that scarab beetle larvae possess great potential to be a source of novel chitinolytic bacteria, that can be exploited for management of phyto-pathogenic fungi, bacteria and insect pests.

Preparation of nanoparticles with the desired shape and size by the wet-chemical precipitation process is a challenging task. Thus, the effects of different substitutional impurities such as Al, Cr, Co or Ni on the particle morphology and phase stability of goethite have been investigated. Goethite is prepared by air oxidation of Fe(OH)₂ · xH₂O gel under near neutral conditions. Below certain concentration levels of dopants (Al³⁺ ≤ 10; Cr³⁺ ≤ 5; Co²⁺ ≤ 10 and Ni²⁺ ≤ 5 at.%) the samples remained monophasic as revealed by XRD, TEM, and IR studies. Above these levels, the substituents produce traces of secondary phases such as lepidocrocite, spinel ferrite and Mⁿ(OH)ₙ. The goethite structure is stable in spite of the iso- or aliovalent substitutions. The individual additives have divergent influence on the particle morphology; Al³⁺ and Cr³⁺ decreases the particle size to <50 nm and aspect ratio (AR) <2. Co-substitution produces slender particles with AR as high as 25. Whereas, Ni²⁺ does not have any influence on the particle morphology. The attributable factors in morphology control are the increased nucleation rate, restricted growth along needle axes, and the strain induced in the goethite lattice as a result of difference in ionic radii. Maghemite, γ-Fe₂O₃₋δ, particles are obtained from goethite wherein the topotactic conversion renders the retention of the particle morphology of the precursor. Maghemite with substituted impurities showed substantial differences in magnetic properties. Saturation magnetization (σₛ) and coercivity (H c) go down to very low values due to relaxation of spins on the surface atoms as revealed by Mössbauer spectroscopy. Decrease in coercivity is by way of the presence of diamagnetic ion (Al³⁺). Whereas, Co-substituted maghemite has enhanced H c as a result of high magnetocrystalline anisotropy accompanied by the shape anisotropy.