Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Insights in the Global Genetics and Gut Microbiome of Black Soldier Fly, Hermetia illucens: Implications for Animal Feed Safety Control
    Khamis, Fathiya M. ; Ombura, Fidelis L.O. ; Akutse, Komivi S. ; Subramanian, Sevgan ; Mohamed, Samira A. ; Fiaboe, Komi K.M. ; Saijuntha, Weerachai ; Loon, Joop J.A. Van; Dicke, Marcel ; Dubois, Thomas ; Ekesi, Sunday ; Tanga, Chrysantus M. - \ 2020
    Frontiers in Microbiology 11 (2020). - ISSN 1664-302X
    16S-metagenomics - genetic diversity - gut microbiome - Hermetia illucens - mitochondrial COI gene

    The utilization of the black soldier fly (BSF) Hermetia illucens L. for recycling organic waste into high-quality protein and fat biomass for animal feeds has gained momentum worldwide. However, information on the genetic diversity and environmental implications on safety of the larvae is limited. This study delineates genetic variability and unravels gut microbiome complex of wild-collected and domesticated BSF populations from six continents using mitochondrial COI gene and 16S metagenomics. All sequences generated from the study linked to H. illucens accessions KM967419.1, FJ794355.1, FJ794361.1, FJ794367.1, KC192965.1, and KY817115.1 from GenBank. Phylogenetic analyses of the sequences generated from the study and rooted by GenBank accessions of Hermetia albitarsis Fabricius and Hermetia sexmaculata Macquart separated all samples into three branches, with H. illucens and H. sexmaculata being closely related. Genetic distances between H. illucens samples from the study and GenBank accessions of H. illucens ranged between 0.0091 and 0.0407 while H. sexmaculata and H. albitarsis samples clearly separated from all H. illucens by distances of 0.1745 and 0.1903, respectively. Genetic distance matrix was used to generate a principal coordinate plot that further confirmed the phylogenetic clustering. Haplotype network map demonstrated that Australia, United States 1 (Rhode Island), United States 2 (Colorado), Kenya, and China shared a haplotype, while Uganda shared a haplotype with GenBank accession KC192965 BSF from United States. All other samples analyzed had individual haplotypes. Out of 481,695 reads analyzed from 16S metagenomics, four bacterial families (Enterobactereaceae, Dysgonomonadaceae, Wohlfahrtiimonadaceae, and Enterococcaceae) were most abundant in the BSF samples. Alpha-diversity, as assessed by Shannon index, showed that the Kenyan and Thailand populations had the highest and lowest microbe diversity, respectively; while microbial diversity assessed through Bray Curtis distance showed United States 3 (Maysville) and Netherlands populations to be the most dissimilar. Our findings on genetic diversity revealed slight phylogeographic variation between BSF populations across the globe. The 16S data depicted larval gut bacterial families with economically important genera that might pose health risks to both animals and humans. This study recommends pre-treatment of feedstocks and postharvest measures of the harvested BSF larvae to minimize risk of pathogen contamination along the insect-based feed value chain.

    Plural valuation of nature for equity and sustainability : Insights from the Global South
    Zafra-Calvo, Noelia ; Balvanera, Patricia ; Pascual, Unai ; Merçon, Juliana ; Martín-López, Berta ; Noordwijk, Meine van; Mwampamba, Tuyeni Heita ; Lele, Sharachchandra ; Ifejika Speranza, Chinwe ; Arias-Arévalo, Paola ; Cabrol, Diego ; Cáceres, Daniel M. ; O'Farrell, Patrick ; Subramanian, Suneetha Mazhenchery ; Devy, Soubadra ; Krishnan, Siddhartha ; Carmenta, Rachel ; Guibrunet, Louise ; Kraus-Elsin, Yoanna ; Moersberger, Hannah ; Cariño, Joji ; Díaz, Sandra - \ 2020
    Global environmental change : human and policy dimensions 63 (2020). - ISSN 0959-3780
    Environmental valuation - Knowledge co-production - Power relations - Transdisciplinarity - Values

    Plural valuation is about eliciting the diverse values of nature articulated by different stakeholders in order to inform decision making and thus achieve more equitable and sustainable outcomes. We explore what approaches align with plural valuation on the ground, as well as how different social-ecological contexts play a role in translating plural valuation into decisions and outcomes. Based on a co-constructed analytical approach relying on empirical information from ten cases from the Global South, we find that plural valuation contributes to equitable and sustainable outcomes if the valuation process: 1) is based on participatory value elicitation approaches; 2) is framed with a clear action-oriented purpose; 3) provides space for marginalized stakeholders to articulate their values in ways that can be included in decisions; 4) is used as a tool to identify and help reconcile different cognitive models about human-nature relations; and 5) fosters open communication and collaboration among stakeholders. We also find that power asymmetries can hinder plural valuation. As interest and support for undertaking plural valuation grows, a deeper understanding is needed regarding how it can be adapted to different purposes, approaches, and social-ecological contexts in order to contribute to social equity and sustainability.

    Effect of dietary replacement of fishmeal by insect meal on growth performance, blood profiles and economics of growing pigs in Kenya
    Chia, Shaphan Y. ; Tanga, Chrysantus M. ; Osuga, Isaac M. ; Alaru, Alphonce O. ; Mwangi, David M. ; Githinji, Macdonald ; Subramanian, Sevgan ; Fiaboe, Komi K.M. ; Ekesi, Sunday ; Loon, Joop J.A. van; Dicke, Marcel - \ 2019
    Animals 9 (2019)10. - ISSN 2076-2615
    Alternative protein - Animal feeds - Blood parameters - Cost benefit analysis - Growing pigs - Insect larval meal - Return on investment

    Pig production is one of the fastest growing livestock sectors. Development of this sector is hampered by rapidly increasing costs of fishmeal (FM), which is a common protein source in animal feeds. Here, we explored the potential of substituting FM with black soldier fly larval meal (BSFLM) on growth and blood parameters of pigs as well as economic aspects. At weaning, 40 hybrid pigs, i.e., crossbreeds of purebred Large White and Landrace were randomly assigned to five iso-nitrogenous and iso-energetic dietary treatments: Control (0% BSFLM and 100% FM (T0)), and FM replaced at 25% (T25), 50% (T50), 75% (T75) and 100% (T100) with BSFLM. Average daily feed intake (ADFI), average daily gain (ADG), body weight gain (BWG) and feed conversion ratio (FCR) were calculated for the whole trial. Hematological and serum biochemical parameters, the cost– benefit ratio (CBR) and return on investment (RoI) were evaluated. No significant effect of diet type was observed on feed intake and daily weight gain. Red or white blood cell indices did not differ among diets. Pigs fed T25, T75 and T100, had lower platelet counts compared to T0 and T50. Dietary inclusion of BSFLM did not affect blood total cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein. CBR and RoI were similar for the various diets. In conclusion, BSFLM is a suitable and cost-effective alternative to fishmeal in feed for growing pigs.

    The nutritive value of black soldier fly larvae reared on common organic waste streams in Kenya
    Shumo, Marwa ; Osuga, Isaac M. ; Khamis, Fathiya M. ; Tanga, Chrysantus M. ; Fiaboe, Komi K.M. ; Subramanian, Sevgan ; Ekesi, Sunday ; Huis, Arnold van; Borgemeister, Christian - \ 2019
    Scientific Reports 9 (2019). - ISSN 2045-2322

    In Africa, livestock production currently accounts for about 30% of the gross value of agricultural production. However, production is struggling to keep up with the demands of expanding human populations, the rise in urbanization and the associated shifts in diet habits. High costs of feed prevent the livestock sector from thriving and to meet the rising demand. Insects have been identified as potential alternatives to the conventionally used protein sources in livestock feed due to their rich nutrients content and the fact that they can be reared on organic side streams. Substrates derived from organic by-products are suitable for industrial large-scale production of insect meal. Thus, a holistic comparison of the nutritive value of Black Soldier Fly larvae (BSFL) reared on three different organic substrates, i.e. chicken manure (CM), brewers’ spent grain (SG) and kitchen waste (KW), was conducted. BSFL samples reared on every substrate were collected for chemical analysis after the feeding process. Five-hundred (500) neonatal BSFL were placed in 23 × 15 cm metallic trays on the respective substrates for a period of 3–4 weeks at 28 ± 2 °C and 65 ± 5% relative humidity. The larvae were harvested when the prepupal stage was reached using a 5 mm mesh size sieve. A sample of 200 grams prepupae was taken from each replicate and pooled for every substrate and then frozen at −20 °C for chemical analysis. Samples of BSFL and substrates were analyzed for dry matter (DM), crude protein (CP), ether extracts (EE), ash, acid detergent fibre (ADF), neutral detergent fibre (NDF), amino acids (AA), fatty acids (FA), vitamins, flavonoids, minerals and aflatoxins. The data were then subjected to analysis of variance (ANOVA) using general linear model procedure. BSFL differed in terms of nutrient composition depending on the organic substrates they were reared on. CP, EE, minerals, amino acids, ADF and NDF but not vitamins were affected by the different rearing substrates. BSFL fed on different substrates exhibited different accumulation patterns of minerals, with CM resulting in the largest turnover of minerals. Low concentrations of heavy metals (cadmium and lead) were detected in the BSFL, but no traces of aflatoxins were found. In conclusion, it is possible to take advantage of the readily available organic waste streams in Kenya to produce nutrient-rich BSFL-derived feed.

    Distant Non-Obvious Mutations Influence the Activity of a Hyperthermophilic Pyrococcusfuriosus Phosphoglucose Isomerase
    Subramanian, Kalyanasundaram ; Mitusińska, Karolina ; Raedts, John ; Almourfi, Feras ; Joosten, Henk Jan ; Hendriks, Sjon ; Sedelnikova, Svetlana E. ; Kengen, Servé W.M. ; Hagen, Wilfred R. ; Góra, Artur ; Martins Dos Santos, Vitor A.P. ; Baker, Patrick J. ; Oost, John van der; Schaap, Peter J. - \ 2019
    Biomolecules 9 (2019)6. - ISSN 2218-273X
    Comulator - cupin phosphoglucose isomerase - Protein engineering - Pyrococcus furiosus - solvent access

    The cupin-type phosphoglucose isomerase (PfPGI) from the hyperthermophilic archaeon Pyrococcus furiosus catalyzes the reversible isomerization of glucose-6-phosphate to fructose-6-phosphate. We investigated PfPGI using protein-engineering bioinformatics tools to select functionally-important residues based on correlated mutation analyses. A pair of amino acids in the periphery of PfPGI was found to be the dominant co-evolving mutation. The position of these selected residues was found to be non-obvious to conventional protein engineering methods. We designed a small smart library of variants by substituting the co-evolved pair and screened their biochemical activity, which revealed their functional relevance. Four mutants were further selected from the library for purification, measurement of their specific activity, crystal structure determination, and metal cofactor coordination analysis. Though the mutant structures and metal cofactor coordination were strikingly similar, variations in their activity correlated with their fine-tuned dynamics and solvent access regulation. Alternative, small smart libraries for enzyme optimization are suggested by our approach, which is able to identify non-obvious yet beneficial mutations.

    Influence of temperature on selected life-history traits of black soldier fly (Hermetia illucens) reared on two common urban organic waste streams in Kenya
    Shumo, Marwa ; Khamis, Fathiya M. ; Tanga, Chrysantus M. ; Fiaboe, Komi K.M. ; Subramanian, Sevgan ; Ekesi, Sunday ; Huis, Arnold Van ; Borgemeister, Christian - \ 2019
    Animals 9 (2019)3. - ISSN 2076-2615
    Black soldier fly (BSF) - Development - Fecundity - Growth - Longevity - Organic waste bioconversion - Rearing temperature

    In sub-Saharan Africa, urban populations are projected to increase by 115% in the coming 15 years. In addition, economic growth and dietary shifts towards animal source foods have put high pressure and demand on agricultural production. The high ecological footprint of meat and dairy production, as well as high feed costs, prevent the livestock sector from meeting the increasing demand in a sustainable manner. Insects such as the black soldier fly (BSF) have been identified as potential alternatives to the conventionally used protein sources in livestock feed due to their rich nutrient content and the fact that they can be reared on organic side streams. Substrates derived from organic byproducts are suitable for industrial large-scale production of insect meal. Although efficient in waste management and in feed production, BSF larvae are very sensitive to the external environment such as temperature and rearing medium. Therefore, we studied the effect of temperature and substrate type, i.e., brewers’ spent grain (SG) and cow dung (CD), on the development and survival of BSF larvae. Both organic substrates were readily available in Nairobi, Kenya, the location of the experiments. In our experiment, 100 3–5-day-old BSF larvae were placed into containers that contained either SG or CD and further treated at temperatures of 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C. The duration of larval development was recorded, and the prepupae were removed, weighed, and placed individually in separate, labeled, 35-mL plastic cups filled with moist sawdust. After emergence, 10 2-day-old adults (5 males and 5 females) from every replica per substrate were transferred into a cage (40 × 40 × 40 cm) and allowed to mate for 24 h at their respective temperatures. The laid egg batches were collected and counted, and the adult flies’ longevity was recorded. The data were subjected to a two-way analysis of variance (ANOVA) using the general linear model procedure. BSF larvae reared on SG developed faster than those reared on CD; the former also favored higher temperatures for their larval development and emergence into adults. The optimum range was 25–30 °C. With increasing temperatures, the longevity of adult BSF decreased, while the fecundity of females increased. Thus, it is possible to take advantage of the readily available SG waste streams in the urban environments of Kenya to produce BSF larvae-derived livestock feed within a short duration of time and at relatively high temperatures.

    Characterization of Male-Produced Aggregation Pheromone of the Bean Flower Thrips Megalurothrips sjostedti (Thysanoptera: Thripidae)
    Niassy, Saliou ; Tamiru, Amanuel ; Hamilton, James G.C. ; Kirk, William D.J. ; Mumm, R. ; Sims, Cassie ; Kogel, W.J. de; Ekesi, Sunday ; Maniania, N.K. ; Bandi, Krishnakumari ; Mitchell, Fraser ; Subramanian, Sevgan - \ 2019
    Journal of Chemical Ecology 45 (2019). - ISSN 0098-0331 - p. 348 - 355.
    Aggregation of the bean flower thrips, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), has been observed on cowpea, Vigna unguiculata (L.) Walp. To understand the mechanism underpinning this behavior, we studied
    the responses of M. sjostedti to headspace volatiles from conspecifics in a four-arm olfactometer. Both male and female M. sjostedti were attracted to male, but not to female odor. Gas chromatography/mass spectrometry (GC/
    MS) analyses revealed the presence of two distinct compounds in male M. sjostedti headspace, namely (R)-lavandulyl 3-methylbutanoate (major compound) and (R)-lavandulol (minor compound); by contrast, both compounds were only present in trace amounts in female headspace collections. A behavioral assay using synthetic compounds showed that male M. sjostedti was attracted to both (R)-lavandulyl 3-methylbutanoate and (R)-lavandulol, while females responded only to (R)-lavandulyl 3-methylbutanoate. This is the first report of a male-produced aggregation pheromone in the genus Megalurothrips. The bean flower thrips is the primary pest of cowpea, which is widely grown in sub-Saharan Africa. The attraction of male and female M. sjostedti to these compounds offers an opportunity to develop ecologically sustainable management methods for M. sjostedti in Africa.
    Muscle growth mechanisms in response to isoenergetic changes in dietary non-protein energy source at low and high protein levels in juvenile rainbow trout
    Alami-Durante, Hélène ; Cluzeaud, Marianne ; Bazin, Didier ; Schrama, Johan W. ; Saravanan, Subramanian ; Geurden, Inge - \ 2019
    Comparative Biochemistry and Physiology. A, Molecular and Integrative Physiology 230 (2019). - ISSN 1095-6433 - p. 91 - 99.
    This study investigates muscle growth mechanisms in juvenile rainbow trout in response to isoenergetic changes in dietary non-protein energy (NPE) source (F, fat vs. C, carbohydrates) at two levels of digestible protein to digestible energy (DP/DE) ratio. Fish (initial weight 32.4 g) were fed four diets having similar DE levels (~18 kJ g−1) with a high (HP/E~26 mg kJ−1) vs. low (LP/E~14 mg kJ−1) DP/DE ratio using F or C as major NPE source (7 week-experiment). The lowering of dietary DP/DE ratio increased myoblast determination protein 1a (myod1a) and decreased myostatin 1b (mstn1b) and cathepsin D (ctsd) muscle mRNA levels. The isoenergetic change in dietary NPE from F to C decreased myod1a and proliferative cell nuclear antigen (pcna) muscle mRNA levels. An interaction between DP/DE ratio and NPE source was observed in muscle transcript levels of myogenic factor 6 (mrf4/myf6), fast myosin heavy chain (fmhc) and fast myosin light chain 2 (fmlc2). White muscle total cross-sectional area decreased at low dietary DP/DE ratio and also when NPE source changed from F to C, linked i) to a decreased total number of white muscle fibres, indicating that low dietary DP/DE restricted muscle hyperplasia and that dietary carbohydrate were less efficiently used than fat to sustain muscle hyperplasia, and ii) to decreased percentage of large muscle fibres, indicating limited fibre hypertrophy. Not only the DP level or the DP/DE ratio, but also the isoenergetic change in dietary NPE source (fat vs carbohydrates) thus appears as a potent regulator of muscle hyperplasia and hypertrophy.
    Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens - links to files
    Chia, Shaphan ; Tanga, Chrysantus Mbi ; Khamis, Fathiya M. ; Mohamed, Samira A. ; Salifu, Daisy ; Sevgan, Subramanian ; Fiaboe, Komi K.M. ; Niassy, Saliou ; Loon, Joop van; Dicke, Marcel ; Ekesi, Sunday - \ 2018
    International Centre of Insect Physiology and Ecology (ICIPE)
    Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers' yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10 - 42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4 °C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0 °C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (r_m=0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.
    Effects of dietary protein level and non-protein energy source on muscle growth mechanisms in rainbow trout (Oncorhynchus mykiss) juveniles
    Alami-Durante, H. ; Cluzeaud, M. ; Bazin, D. ; Schrama, J.W. ; Subramanian, S. ; Geurden, Inge - \ 2018
    - 1 p.
    Modulating D-amino acid oxidase (DAAO) substrate specificity through facilitated solvent access
    Subramanian, Kalyanasundaram ; Góra, Artur ; Spruijt, Ruud ; Mitusińska, Karolina ; Suarez-Diez, Maria ; Martins Dos Santos, Vitor ; Schaap, Peter J. - \ 2018
    PLoS ONE 13 (2018)6. - ISSN 1932-6203

    D-amino acid oxidase (DAAO) degrades D-amino acids to produce α-ketoacids, hydrogen peroxide and ammonia. DAAO has often been investigated and engineered for industrial and clinical applications. We combined information from literature with a detailed analysis of the structure to engineer mammalian DAAOs. The structural analysis was complemented with molecular dynamics simulations to characterize solvent accessibility and product release mechanisms. We identified non-obvious residues located on the loops on the border between the active site and the secondary binding pocket essential for pig and human DAAO substrate specificity and activity. We engineered DAAOs by mutating such critical residues and characterised the biochemical activity of the resulting variants. The results highlight the importance of the selected residues in modulating substrate specificity, product egress and enzyme activity, suggesting further steps of DAAO re-engineering towards desired clinical and industrial applications.

    Effects of waste stream combinations from brewing industry on performance of black soldier fly, Hermetia illucens (Diptera: Stratiomyidae)
    Chia, Shaphan Y. ; Tanga, Chrysantus M. ; Osuga, Isaac M. ; Mohamed, Samira A. ; Khamis, Fathiya M. ; Salifu, Daisy ; Sevgan, Subramanian ; Fiaboe, Komi K.M. ; Niassy, Saliou ; Loon, Joop J.A. van; Dicke, Marcel ; Ekesi, Sunday - \ 2018
    PeerJ 2018 (2018)11. - ISSN 2167-8359
    Agro-industrial by-products - Hermetia illucens - Mass rearing - Net energy - Protein quality - Quality control parameters

    Background: In recent years, there has been a rapidly growing demand for readily accessible substrates for mass production of Black Soldier Fly, Hermetia illucens Linnaeus. Beer production results in various by-products that typically end up in uncontrolled dumpsites constituting pollution problems, which merits urgent attention. The present study investigated whether the 12 formulated diets composed of brewers’ spent grains (BSGs), brewers’ yeast and cane molasses can serve as substrate for H. illucens production. Methods: Four different BSGs were selected and formulated into 12 diets, aiming at varying protein and net energy levels. The diets were offered to newly hatched (∼1 h old) H. illucens larvae and the influence on developmental duration, survival, wet weight, pre-oviposition time, fecundity, and longevity were compared. Results: Developmental duration of the larvae (16–21 days) and pre-pupae (8–11 days) differed significantly across the different diets. The developmental duration of the pupae (8.7–9.1 days) was not affected by diet. The larval (86–99.2%), pre-pupal (71–95%), and pupal (65–91%) survival rates varied significantly between flies reared on the different diets. The pre-oviposition time was similar for flies provided with water (7–11 days) and 10% sugar solution (8–14 days) or across the different diets. The mean fecundity per female ranged from 324–787 eggs and did not differ between females provided with water or sugar solution. However, the number of eggs laid per female varied significantly across the different diets when provided with water. The longevity of starved H. illucens adults was significantly lower (5 days) compared to those provided with water (11–14 days) or sugar solution (14–15 days). Discussion: The implications of these findings as part of a quality control procedure for commercial production of high-quality H. illucens larvae as an alternative protein ingredient in livestock and aquaculture feed are discussed.

    Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens : Implications for mass production
    Chia, Shaphan Yong ; Tanga, Chrysantus Mbi ; Khamis, Fathiya M. ; Mohamed, Samira A. ; Salifu, Daisy ; Sevgan, Subramanian ; Fiaboe, Komi K.M. ; Niassy, Saliou ; Loon, Joop J.A. van; Dicke, Marcel ; Ekesi, Sunday - \ 2018
    PLoS ONE 13 (2018)11. - ISSN 1932-6203

    Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers' yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10-42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4°C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0°C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (rm = 0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.

    On jet instability modes of a subsonic Hartmann whistle
    Varadharajan, Ramanathan ; Kamin, Manu ; Ganesh, Subramanian ; Mathew, Joseph - \ 2018
    Sadhana 43 (2018)9. - ISSN 0256-2499
    Hartmann whistle - jet-instability mode - large-eddy simulation - subsonic flow

    Numerical experiments to understand the resonant acoustic response of a subsonic jet impinging on the mouth of a tube, known as the Hartmann whistle configuration, were performed as large-eddy simulations. The tube length was chosen so that its fundamental duct mode, for one end closed and one end open, would match the dominant mode in the exciting jet. When the tube mouth was placed in the path of a regular stream of vortex rings, formed by the instability of the jet’s bounding shear layer, a strong resonant, tonal response (whistling) was obtained. At three diameters from the jet, OASPL was 150–160 dB. A tube with a thicker lip generated a louder response. When the tube was held closer to the nozzle exit, the impinging unsteady shear layer could not provoke any significant resonance. The simulations reveal that the tonal response of a Hartmann whistle operating in subsonic mode is significant.

    CorNet: Assigning function to networks of co-evolving residues by automated literature mining
    Bergh, Tom Van Den; Tamo, Giorgio ; Nobili, Alberto ; Tao, Yifeng ; Tan, Tianwei ; Bornscheuer, Uwe T. ; Kuipers, Remko K.P. ; Vroling, Bas ; Jong, René M. De; Subramanian, Kalyanasundaram ; Schaap, Peter J. ; Desmet, Tom ; Nidetzky, Bernd ; Vriend, Gert ; Joosten, Henk-Jan - \ 2017
    PLoS ONE 12 (2017)5. - ISSN 1932-6203 - p. e0176427 - e0176427.
    CorNet is a web-based tool for the analysis of co-evolving residue positions in protein super-family sequence alignments. CorNet projects external information such as mutation data extracted from literature on interactively displayed groups of co-evolving residue positions to shed light on the functions associated with these groups and the residues in them. We used CorNet to analyse six enzyme super-families and found that groups of strongly co-evolving residues tend to consist of residues involved in a same function such as activity, specificity, co-factor binding, or enantioselectivity. This finding allows to assign a function to residues for which no data is available yet in the literature. A mutant library was designed to mutate residues observed in a group of co-evolving residues predicted to be involved in enantioselectivity, but for which no literature data is available yet. The resulting set of mutations indeed showed many instances of increased enantioselectivity.
    Active aggregation among sexes in bean flower thrips (Megalurothrips sjostedti) on cowpea (Vigna unguiculata)
    Niassy, Saliou ; Ekesi, Sunday ; Maniania, N.K. ; Orindi, Benedict ; Moritz, G.B. ; Kogel, W.J. de; Subramanian, Sevgan - \ 2016
    Entomologia Experimentalis et Applicata 158 (2016)1. - ISSN 0013-8703 - p. 17 - 24.
    Aggregation behaviour - Dispersion index - Fabaceae - Grain legumes - Semiochemical - Thripidae - Thysanoptera

    Male sexual aggregations are a common territorial, mating-related or resource-based, behaviour observed in diverse organisms, including insects such as thrips. The influence of factors such as plant substrate, time of day, and geographic location on aggregation of thrips is uncertain, therefore we monitored the dispersion of male and female bean flower thrips (BFT), Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), on cowpea, Vigna unguiculata (L.) Walp. (Fabaceae), over three cowpea growth stages and across three cowpea-growing areas of Kenya. Our results indicated that for all the crop growth stages, the density of BFTs varied over the time of day, with higher densities at 10:00, 13:00, and 16:00 hours than at 07:00 hours. Thrips densities did not differ among blocks at the budding stage, but they did at peak flowering and podding stages. Dispersion indices suggested that both male and female BFTs were aggregated. Active male aggregation occurred only on green plant parts and it varied across blocks, crop stages, and locations. Similarly, active female aggregation was observed in peak flowering and podding stages. Such active aggregation indicates a semiochemical or behaviour-mediated aggregation. Identification of such a semiochemical may offer new opportunities for refining monitoring and management strategies for BFT on cowpea, the most important grain legume in sub-Saharan Africa.

    Spatial separation of semiochemical Lurem-TR and entomopathogenic fungi to enhance their compatibility and infectivity in an autoinoculation system for thrips management
    Mfuti, D.K. ; Subramanian, S. ; Tol, R.W.H.M. van; Wiegers, G.L. ; Kogel, W.J. de; Niassy, S. ; Plessis, H. du; Ekesi, S. ; Maniania, N.K. - \ 2016
    Pest Management Science 72 (2016)1. - ISSN 1526-498X - p. 131 - 139.

    BACKGROUND
    The effect of spatial separation of the semiochemical Lurem-TR, which has been found to inhibit conidia of entomopathogenic fungi when put together, on the persistence of conidia of Metarhizium brunneum and M. anisopliae was evaluated in the greenhouse and field in order to develop an autodissemination strategy for the management of Megalurothrips sjostedti on cowpea crop. Influence of spatial separation of the semiochemical on thrips attraction and conidial acquisition by thrips from the autoinoculation device was also investigated in the field.
    RESULTS
    Persistence of conidia of M. brunneum and M. anisopliae increased with distance of separation of Lurem-TR. Direct exposure of fungus without separation from Lurem-TR recorded the lowest conidial germination as compared with the other treatments. Attraction of thrips to the device also varied significantly according to distance between device and semiochemical, with a higher number of thrips attracted when Lurem-TR was placed in a container below the device and at 10 cm distance. There was no significant difference in conidial acquisition between spatial separation treatments of conidia and Lurem-TR. Attraction of other insect pests to the device did not significantly vary between treatments. Positive correlations were found between conidial acquisition and thrips attraction.
    CONCLUSION
    This study suggests that spatial separation of fungal conidia from Lurem-TR in an autoinoculation device could provide a low-cost strategy for effective management of thrips in grain legume cropping systems.

    Traditional medicine
    Payyappallimana, U. ; Subramanian, M. ; Timoshyna, A. ; Graz, B. ; Leaman, D. ; Bussmann, R.W. ; Hariramamurthi, G. ; Shankar, D. ; Klooster, C.I.E.A. van 't; Bodeker, G. ; Sekagya, Y. ; Hemstra, W. ; Gomez, F. ; Verschuuren, B. ; Ravin, E. de; Ligare, J. ; Reid, A.M. ; Petersen, L.M. - \ 2015
    In: Connecting Global Priorities: Biodiversity and Human Health World Health Organization - ISBN 9789241508537 - p. 180 - 199.
    An analysis of community well-being in biocultural landscapes: are we living well?
    Verschuuren, Bas ; Subramanian, Suneetha M. ; Hiemstra, Wim - \ 2014
    In: Community Well-being in Biocultural Landscapes / Verschuuren, Bas, Subramanian, Suneetha M., Hiemstra, Wim, Practical Action Publishing - ISBN 9781853398384 - p. 122 - 147.
    This chapter draws conclusions from an analysis of the importance of well-being assessment from a community perspective, which is different from the sum of individual assessments. One of the reasons is that biocultural relationships in the landscape express themselves at the community level and this expression of shared and often cultural experience can be different from its expression at the individual level. External support to endogenous processes in communities includes the capacity of support organizations to understand and facilitate community-level assessments. Several stages for such support can be identified in the cases presented in this book. A plea is made to integrate interior dimensions, such as the sociological, psychological, religious and behavioural, in community well-being assessments. For policies to succeed, they have to take community realities – social, spiritual, and material – into account.
    Community well-being in Ghana: an African perspective
    Guri, Bernard Yangmaadome ; Verschuuren, Bas - \ 2014
    In: Community Well-being in Biocultural Landscapes / Verschuuren, Bas, Subramanian, Suneetha M., Hiemstra, Wim, Practical Action Publishing - ISBN 9781853398384 - p. 78 - 100.
    This chapter tells the story of well-being in the Forikrom community through its search for conservation and revitalization of sacred caves as part of the development of an ecotourism and environmental restoration project. The community applies the endogenous development approach and is supported by the Centre for Indigenous Knowledge and Organizational Development (CIKOD), a Ghanaian NGO. The focus of the chapter is to demonstrate that different well-being assessment approaches and methods have been applied and how these helped both the community and the NGO to a better understanding of the changes in community well-being before and after the development projects.
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