Comparative toxicity of phosphine to developmental stages of three Callosobruchus species infesting stored pulses

Aidbhavi Revanasidda,Subramanian Sabtharishi,Ranjitha M.R.,Chandel Rahul Kumar,Srivastava Chitra,Bandi Sanjay M.,Singh Bansa 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.1

Bruchids pose serious threat to stored pulses, and their successful management largely depends on phosphine fumigation. For the first time, the comparative assessment of phosphine toxicity to all the developmental stages of three bruchid species in India was attempted at varied concentrations and exposure times. Based on probit estimates, the egg stages found to be least sensitive to phosphine followed by pupae and larvae, whereas adults were highly sensitive. Among the age groups of eggs, the early age groups (0–2 days old) were less sensitive than later stages (3–6 days old). The bruchid species viz., Callosobruchus maculatus (F.), C. analis (F.), and C. chinensis L. exhibited a variable degree of susceptibility irrespective of life stages and exposure periods tested. However, the collective probit estimates indicated C. maculatus being slightly less sensitive followed by C. analis and C. chinensis. Except in 0–2 day old eggs, the mortality response in 3–6 day old eggs, larvae, pupae, and adults was increased with increasing phospine concentrations and exposure period. The mortality response got even steeper at 48 and 72 h exposures as evident by decreasing LC50 and LC90 values. The information generated on phospine sensitivity in different life stages would serve as baseline data to design insecticide resistance studies in future and also to ascertain stage-specific Concentration vs. time (Ct) products for the recommendation of phosphine doses for successful management of bruchids during any of their life stages under storage conditions.

Inheritance pattern and expression of resistance to phosphine in larval stage of Tribolium castaneum (Coleoptera: Tenebrionidae)

Ramya R.S.,Srivastava Chitra,Subramanian Sabtharishi,Ranjith M. 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.1

Resistance developed by Tribolium castaneum (Herbst), a major pest of stored grain and grain products, to phosphine is a serious concern. Treatment of phosphine is given to all the stages (egg, larva, pupa and adult) of insects simultaneously in the infected commodity. Effective resistance management tactics need a proper un derstanding of expression of resistance in relation to dosage in immature stages including larvae. So, this study was undertaken to understand the genetic basis of phosphine resistance in larval stage of T. castaneum by crossing the resistant and susceptible parents to obtain the F 1 , F 2 and the back-cross progenies. The resistant parent had a resistance ratio of 37.75 when compared to the susceptible parent. The susceptibility levels of the reciprocal F 1 hybrids did not show any significant difference indicating autosomal mode of inheritance of resistance. Level of dominance for the reciprocal F 1 hybrids was estimated (-0.70 and − 0.68) which showed that the resistance is expressed as incompletely recessive in larval stage of T. castaneum. χ 2 analysis showed that the observed and expected mortalities differed significantly (P < 0.05) in most of the concentrations indicating that more than one gene is responsible for phosphine resistance. Two plateaus at ~ 40 % and ~ 90 % mortality levels for the backcross progeny to the resistant parent further confirmed the involvement of two or more genes in imparting resistance to phosphine. Our results will aid in enhancing the knowledge on the development of resistance to phosphine in the field and thus facilitate in designing suitable resistance management tactics.

Optimization and characterization of extracellular cellulase produced by Bacillus pumilus MGB05 isolated from midgut of muga silkworm (Antheraea assamensis Helfer)

Pinky Moni Bhuyan,Sosanka Protim Sandilya,Pranab Kumar Nath,Sakshi Gandotra,Sabtharishi Subramanian,Devid Kardong,Dip Kumar Gogoi 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

Mature larvae of Antheraea assamensis were collected from different locations of Assam to isolate the cellulolytic gut microflora. Altogether sixty cellulase degrading bacteria were isolated on agar plates containing microcrystalline cellulose as the sole carbon source. Among them, ten isolates showed hydrolyzing zone on agar plates containing carboxy methyl cellulose (CMC) after staining with Congo-red. Isolate MGB05 exhibited the highest CMCase activity (0.262 U/mL) at 72 h of incubation under submerged condition. FPase and β-glucosidase activity were 0.012 U/mL and 3.71 U/mL respectively. It showed maximum FPase (0.022 U/mL) activity on the 3rd day of incubation in the media containing wheat bran as a carbon source. β-glucosidase production was also found to be highest with wheat bran (20.03 U/mL) at 48 h of incubation. The optimum pH and temperature of FPase activity of MGB05 were found at 6.0 and 50 °C respectively while for β-glucosidase activity, it was maximum at pH 6.0 under 50 °C. In addition, metal ion Mg ++ and Ca ++ enhanced FPase activity up to 110.92% (0.026 U/mL) and 105.31% (0.025 U/mL) respectively. In-vitro antimicrobial bioassay of the most potent cellulolytic bacteria (MGB05) also showed high antimicrobial activity against Escherichia coli (2.9 cm) and Pseudomonas aeruginosa (3.0 cm). The isolate MGB05 has been identified based on 16S rDNA homology as Bacillus pumilus MGB05 with accession KP298708.2. Results encompass the prospective beneficial role of gutmicroflora on digestion and disease resistance, which might be a potential probiotic component to enhance silk productivity.

Screening and characterization of lipase producing bacteria isolated from the gut of a lepidopteran larvae, Samia ricini

MsangoSoko Kondwani,Gandotra Sakshi,Bhattacharya Ramcharan,Ramakrishnan Balasubramanian,Sharma Kirti,Subramanian Sabtharishi 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.1

Lipolytic enzymes are an important group of hydrolases that have found immense industrial application in biotechnology. In this study, the ability of gut bacteria isolated from the gut of the Eri silkworm, Samia ricini, to produce lipolytic enzymes was evaluated through qualitative and quantitative assays. The results of lipase screening showed that 28 isolates had lipolytic activity. The results of 16S ribosomal RNA sequencing indicated that the genus Bacillus comprised majority of the lipolytic bacterial isolates (71%) followed by Pseudomonas (15%); whilst Acinetobacter, Enterobacter and Enterococcus comprised 11%. Lipolytic activity was found in bac teria isolates identified from all the three gut compartments of S. ricini larvae with significant activity from isolates extracted from the foregut and midgut. The lipolytic index among the bacterial isolates ranged between 0.63 and 2.81 on Rhodamine B medium, and all isolates exhibited significant lipolytic activity with p-nitrophenyl butyrate (PNPB) with specific activity ranging from 0.52 to 0.82 μmol/min/mg. The effect of pH and temperature showed that lipase activity was optimum at 37 ◦ C and pH 7–9. A phylogenetic relationship of lipase producing gut bacteria indicated high cluster stability for isolates from different stages (>50%) suggesting that the isolates persist across developmental stages of the host. The Eri silkworm is reared for its silk and the knowledge of its gut bacteria with the ability to produce lipases lies in the significance as far as boosting production of this insect via development of probiotics to enhance commercial Eri rearing. In addition, this insect may be a good resource for profiling novel lipolytic microbes for commercial production of lipases as lipases from microbial origin have assumed a great deal of importance as industrial enzymes due to their potential for use in biotechnology.

Composition and Diversity of Gut Bacteria Associated with the Eri Silk Moth, Samia ricini, (Lepidoptera: Saturniidae) as Revealed by Culture-Dependent and Metagenomics Analysis

Kondwani MsangoSoko,Sakshi Gandotra,Rahul Kumar Chandel,Kirti Sharma,Balasubramanian Ramakrishinan,Sabtharishi Subramanian 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.9

The polyphagous eri silk moth, Samia ricini, is associated with various symbiotic gut bacteria believed to provide several benefits to the host. The larvae of S. ricini were subjected to isolation of gut bacteria using culture-dependent 16S rRNA generic characterization, metagenomics analysis and qualitative enzymatic assays. Sixty culturable aerobic gut bacterial isolates comprising Firmicutes (54%) and Proteobacteria (46%); and twelve culturable facultative anaerobic bacteria comprising Proteobacteria (92%) and Firmicutes (8%) were identified inhabiting the gut of S. ricini. The results of metagenomics analysis revealed the presence of a diverse community of both culturable and un-culturable gut bacteria belonging to Proteobacteria (60%) and Firmicutes (20%) associated with seven orders. An analysis of the results of culturable isolation indicates that these bacterial isolates inhabited all the three compartments of the gut. Investigation on persistence of bacteria coupled with metagenomics analysis of the fifth instar suggested that bacteria persist in the gut across the different instar stages. In addition, enzymatic assays indicated that 48 and 75% of culturable aerobic, and 75% of anaerobic gut bacterial isolates had cellulolytic, lipolytic and nitrate reductase activities, thus suggesting that they may be involved in food digestion and nutritional provision to the host. These bacterial isolates may be good sources for profiling novel genes and biomolecules for biotechnological application.