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Mutua BK, Dubois T, Akutse KS, Muli B, Karanja EN, Mutyambai DM. Electrophysiological and Behavioral Responses of Cabbage Aphid (Brevicoryne brassicae) to Rosemary (Rosmarinus officinalis) Volatiles, a Potential push Plant for Vegetable push-pull Cropping System. J Chem Ecol 2024:10.1007/s10886-024-01485-y. [PMID: 38470529 DOI: 10.1007/s10886-024-01485-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/23/2024] [Accepted: 03/03/2024] [Indexed: 03/14/2024]
Abstract
The cabbage aphid (Brevicoryne brassicae) is a major pest of kale (Brassica oleraceae var. acephala), an important vegetable that is grown worldwide due to its high nutritional and economic value. Brevicoryne brassicae poses a great challenge to B. oleraceae var. acephala production, causing significant direct and indirect yield losses. Farmers overly rely on synthetic insecticides to manage the pest with limited success owing to its high reproductive behavior and development of resistance. This necessitates a search for sustainable alternatives to mitigate these challenges. This study assessed behavioral responses of B. brassicae to odors from rosemary (Rosmarinus officinalis) and B. oleraceae var. acephala headspace volatiles in a Perspex four-arm olfactometer. We identified and quantified volatiles emitted by each of the two plants and those eliciting antennal response using coupled gas chromatography-mass spectrometry (GC-MS) and GC-electroantennograhic detection(GC-EAD), respectively. Our findings revealed that B. brassicae spent more time in the arms of the olfactometer that contained B. oleraceae var. acephala volatiles compared to the arm that held R. officinalis volatiles. Additionally, B. brassicae spent more time in the olfactometer arms with B. oleracea var. acephala compared to the arms holding B. oleracea var. acephala and R. officinalis enclosed together and clean air. GC-MS analysis revealed diverse and higher quantities of volatile compounds in R. officinalis compared to B. oleraceae var. acephala. GC-EAD analysis showed that antennae of B. brassicae detected Linalool, α-Terpineol, Verbenone, Geraniol, Camphor, and Borneol from the volatiles of R. officinalis, and Sabinene, γ-Terpinene, and β-Caryophyllene from B. oleraceae var. acephala volatiles. Our findings demonstrate the potential of R. officinalis as a repellent plant against B. brassicae and could be utilized as a 'push' plant in an intercropping strategy against this pest.
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Affiliation(s)
- Bretor Katuku Mutua
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
- Department of Agricultural Sciences, South Eastern Kenya University, P.O Box 170-90200, Kitui, Kenya
| | - Thomas Dubois
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
| | - Komivi Senyo Akutse
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520, South Africa
| | - Benjamin Muli
- Department of Agricultural Sciences, South Eastern Kenya University, P.O Box 170-90200, Kitui, Kenya
| | - Edward Nderitu Karanja
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
| | - Daniel Munyao Mutyambai
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya.
- Department of Life Sciences, South Eastern, Kenya University, P.O Box 170-90200, Kitui, Kenya.
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Onyango LA, Ngonga FA, Karanja EN, Kuja JO, Boga HI, Cowan DA, Mwangi KW, Maghenda MW, Marinho Lebre PBN, Kambura AK. The soil microbiomes of forest ecosystems in Kenya: their diversity and environmental drivers. Sci Rep 2023; 13:7156. [PMID: 37130890 PMCID: PMC10154314 DOI: 10.1038/s41598-023-33993-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 04/21/2023] [Indexed: 05/04/2023] Open
Abstract
Soil microbiomes in forest ecosystems act as both nutrient sources and sinks through a range of processes including organic matter decomposition, nutrient cycling, and humic compound incorporation into the soil. Most forest soil microbial diversity studies have been performed in the northern hemisphere, and very little has been done in forests within African continent. This study examined the composition, diversity and distribution of prokaryotes in Kenyan forests top soils using amplicon sequencing of V4-V5 hypervariable region of the 16S rRNA gene. Additionally, soil physicochemical characteristics were measured to identify abiotic drivers of prokaryotic distribution. Different forest soils were found to have statistically distinct microbiome compositions, with Proteobacteria and Crenarchaeota taxa being the most differentially abundant across regions within bacterial and archaeal phyla, respectively. Key bacterial community drivers included pH, Ca, K, Fe, and total N while archaeal diversity was shaped by Na, pH, Ca, total P and total N. To contextualize the prokaryote diversity of Kenyan forest soils on a global scale, the sample set was compared to amplicon data obtained from forest biomes across the globe; displaying them to harbor distinct microbiomes with an over-representation of uncultured taxa such as TK-10 and Ellin6067 genera.
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Affiliation(s)
- Lorine Akinyi Onyango
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya
| | - Florence Atieno Ngonga
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya
| | - Edward Nderitu Karanja
- International Centre for Insect Physiology and Ecology, P.O. Box 30772-00100, Nairobi, Kenya
| | - Josiah Ochieng' Kuja
- Department of Botany, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya
| | - Hamadi Iddi Boga
- School of Agriculture, Earth and Environmental Sciences, Taita Taveta University, P. O. Box 635-80300, Voi, Kenya
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | | | - Marianne Wughanga Maghenda
- School of Agriculture, Earth and Environmental Sciences, Taita Taveta University, P. O. Box 635-80300, Voi, Kenya
| | - Pedro Bixirao Neto Marinho Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Anne Kelly Kambura
- School of Agriculture, Earth and Environmental Sciences, Taita Taveta University, P. O. Box 635-80300, Voi, Kenya.
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Karanja EN, Fliessbach A, Adamtey N, Kambura AK, Musyoka M, Fiaboe K, Mwirichia R. Diversity and structure of prokaryotic communities within organic and conventional farming systems in central highlands of Kenya. PLoS One 2020; 15:e0236574. [PMID: 32790770 PMCID: PMC7425915 DOI: 10.1371/journal.pone.0236574] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 07/08/2020] [Indexed: 01/04/2023] Open
Abstract
Management practices such as tillage, crop rotation, irrigation, organic and inorganic inputs application are known to influence diversity and function of soil microbial populations. In this study, we investigated the effect of conventional versus organic farming systems at low and high input levels on structure and diversity of prokaryotic microbial communities. Soil samples were collected from the ongoing long-term farming system comparison trials established in 2007 at Chuka and Thika in Kenya. Physicochemical parameters for each sample were analyzed. Total DNA and RNA amplicons of variable region (V4-V7) of the 16S rRNA gene were generated on an Illumina platform using the manufacturer's instructions. Diversity indices and statistical analysis were done using QIIME2 and R packages, respectively. A total of 29,778,886 high quality reads were obtained and assigned to 16,176 OTUs at 97% genetic distance across both 16S rDNA and 16S rRNA cDNA datasets. The results pointed out a histrionic difference in OTUs based on 16S rDNA and 16S rRNA cDNA. Precisely, while 16S rDNA clustered by site, 16S rRNA cDNA clustered by farming systems. In both sites and systems, dominant phylotypes were affiliated to phylum Actinobacteria, Proteobacteria and Acidobacteria. Conventional farming systems showed a higher species richness and diversity compared to organic farming systems, whilst 16S rRNA cDNA datasets were similar. Physiochemical factors were associated differently depending on rRNA and rDNA. Soil pH, electrical conductivity, organic carbon, nitrogen, potassium, aluminium, zinc, iron, boron and micro-aggregates showed a significant influence on the observed microbial diversity. The observed higher species diversity in the conventional farming systems can be attributed to the integration of synthetic and organic agricultural inputs. These results show that the type of inputs used in a farming system not only affect the soil chemistry but also the microbial population dynamics and eventually the functional roles of these microbes.
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Affiliation(s)
- Edward Nderitu Karanja
- Department of Biological sciences, University of Embu, Embu, Kenya
- International Centre for Insect Physiology and Ecology, Nairobi, Kenya
| | | | - Noah Adamtey
- Research Institute of Organic Agriculture, Frick, Switzerland
| | - Anne Kelly Kambura
- Taita Taveta University, School of Agriculture, Earth and Environmental Sciences, Voi, Kenya
| | - Martha Musyoka
- International Centre for Insect Physiology and Ecology, Nairobi, Kenya
| | - Komi Fiaboe
- International Centre for Insect Physiology and Ecology, Nairobi, Kenya
- International Institute of Tropical Agriculture, Cameroon, Yaoundé, Cameroon
| | - Romano Mwirichia
- Department of Biological sciences, University of Embu, Embu, Kenya
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