The present investigation was aimed to assess the best organic pest management practices in soybean and Indian rape cultivation systems in the mid-Himalayas. Based on the preliminary laboratory assays, promising treatments were selected for field assays for 3 years. It was observed that Parthenium leaf extract 5% provided significantly higher pest reduction in field condition with 76.8% at 7 DAT (days after treatment) against sucking bug, Chauliops choprai infesting soybean. In case of mustard aphids (Lipaphis erysimi) infesting Indian rape, Nimbicidine 5 ml L À1 was found superior with 61.5% pest reduction, followed by 5% seed extract of Melia azedarach at 7 DAT in field condition. Contrary to pest reduction, the pooled yield data analysis showed that among organic treatments, spraying of Nimbicidine @ 5 ml L À1 recorded significantly superior yield over control with yield advantage of 29%, followed by M. azedarach seed extract 5% and 10%, both recording 21% yield advantage in case of soybean. Nimbicidine was also superior for Indian rape crop with yield advantage of 51%, followed by Beauveria bassiana @ 3 g L À1 with 44% and 5% seed extract of M. azedarach with 33% yield advantage compared to control. Hence, Parthenium leaf extract 5% and Nimbicidine are recommended for effective control of C. choprai and L. erysimi infesting soybean and Indian rape, respectively. But to achieve higher yield, Nimbicidine is the best among organic management of those pests for both crops. These results suggest good organic pest management options in organic farming system.
A microbial pathogen, Bacillus cereus strain WGPSB-2 isolated from mid hills of Uttarakhand Himalayas (1000-1500 amsl) had potential as a biocontrol agent against white grubs of the region. Thus, the pathogen's ability to suppress grubs was investigated under field conditions over a period of five years in five villages of the region. A single dose annual application of WGPSB-2 as talc based formulation (1x10 10 spores/g) at the rate of 5kg/ha showed a sharp decline in grub population over the years in all the targeted villages. Pit sampling data showed maximum grub reduction during initial years of treatment in all villages and found significant for time, villages and time X village interactions in repeated measures ANOVA. Twenty four months post-inoculation resilience took place in micropits tested for bioagent impact on micro-floral densities, resulting in similar/ positive structures of tested microbial populations. The substantial numerical reduction of grub density coupled with no negative impacts on soil inhabitant microbiota, signifies WGPSB-2 as a vibrant technological option in this ecologically sensitive region.
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 LC50 values ranging from 1.7 × 104 to 2.5 × 106 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 × 105 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 × 107 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.
Molecular variation and phylogenetic relationship of Bombus haemorrhoidalis Smith 1852 was studied using partial cytochrome oxidase I (COI) and cytochrome b (cyt b) sequences of mitochondrial genome. The COI and cyt b sequences were compared with available sequences of B. haemorrhoidalis and other Bombus species belonging to different subgenera to avail divergence within and between species. The BLASTn analysis of obtained COI sequence had cent percent identity to a hymenopteran species BOLD deposit AAC6447 (MAHYM005-10.COI-5P) which is a Bombus species from Pakistan. Both these species formed a separate cluster amongst the tested B. haemorrhoidalis species in phylogeny with pair wise genetic distance of 0.003. Moreover, the minimum evolution tree between the species revealed B. haemorrhoidalis is phylogenetically close with B. funerarius and the pair wise genetic distance between these two species was 0.102. Interestingly, B. haemorrhoidalis and B. funerarius formed separate minor cluster amongst the Bombus species tested for phylogeny. Additionally, both COI and cyt b genes were A+T biased and showed single nucleotide polymorphisms between and within species. The phylogenetic relationship of COI sequences also revealed single species status of B. haemorrhoidalis in the Indian Himalayan region and was evolutionarily associated with B. funerarius which is an another species in subgenera, Orientalibombus. The phylogeny of cyt b sequences showed that the B. haemorrhoidalis is evolutionarily close to pennsylvanicus group species. The study illustrates a complex genetic variation coupled with highly structured evolutionary divergences between and within species and provides the first report of cyt b sequence of B. haemorrhoidalis.
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