Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2021
Forfattere
Ghislain T. Tepa-Yotto Henri E. Z. Tonnang Georg Goergen Sevgan Subramanian Emily Kimathi Elfatih M. Abdel-Rahman Daniel Flø Karl Thunes Komi K. M. Fiaboe Saliou Niassy Anani Bruce Samira A. Mohamed Manuele Tamò Sunday Ekesi May-Guri SæthreSammendrag
Simple Summary: The fall armyworm (FAW), Spodoptera frugiperda has now become a pest of global importance. Its introduction and detection in Africa in 2016, and subsequent introduction and spread into Asia and Australia, has put several millions of food producers and maize farmers at risk. Not all pest management strategies are sustainable. Biological control with the use of parasitoid wasps is one of the durable and environmentally sound options. The present study was initiated to predict the habitats of high establishment potential of key parasitoids of FAW in South America, which might prove to be effective as classical biological control agents of FAW in regions where it is an invasive species under current and future climate scenarios. The prospective parasitoids are the following: Chelonus insularis, Cotesia marginiventris, Eiphosoma laphygmae, Telenomus remus and Trichogramma pretiosum. The results demonstrate overlapping habitat suitability areas of the pest and the parasitoids, suggesting promises for biological control options for the management of FAW under current and future climate scenarios. Abstract: The present study is the first modeling effort at a global scale to predict habitat suitability of fall armyworm (FAW), Spodoptera frugiperda and its key parasitoids, namely Chelonus insularis, Cotesia marginiventris, Eiphosoma laphygmae, Telenomus remus and Trichogramma pretiosum, to be considered for biological control. An adjusted procedure of a machine-learning algorithm, the maximum entropy (Maxent), was applied for the modeling experiments. Model predictions showed particularly high establishment potential of the five hymenopteran parasitoids in areas that are heavily affected by FAW (like the coastal belt of West Africa from Côte d’Ivoire (Ivory Coast) to Nigeria, the Congo basin to Eastern Africa, Eastern, Southern and Southeastern Asia and some portions of Eastern Australia) and those of potential invasion risks (western & southern Europe). These habitats can be priority sites for scaling FAW biocontrol efforts. In the context of global warming and the event of accidental FAW introduction, warmer parts of Europe are at high risk. The effect of winter on the survival and life cycle of the pest in Europe and other temperate regions of the world are discussed in this paper. Overall, the models provide pioneering information to guide decision making for biological-based medium and long-term management of FAW across the globe.
Forfattere
Juliet Ochola Danny Coyne Laura Cortada Solveig Haukeland Margaret Ng'ang'a Ahmed Hassanali Charles Opperman Baldwyn TortoSammendrag
Bio-communication occurs when living organisms interact with each other, facilitated by the exchange of signals including visual, auditory, tactile and chemical. The most common form of bio-communication between organisms is mediated by chemical signals, commonly referred to as ‘semiochemicals’, and it involves an emitter releasing the chemical signal that is detected by a receiver leading to a phenotypic response in the latter organism. The quality and quantity of the chemical signal released may be influenced by abiotic and biotic factors. Bio-communication has been reported to occur in both above- and below-ground interactions and it can be exploited for the management of pests, such as cyst nematodes, which are pervasive soil-borne pests that cause significant crop production losses worldwide. Cyst nematode hatching and successful infection of hosts are biological processes that are largely influenced by semiochemicals including hatching stimulators, hatching inhibitors, attractants and repellents. These semiochemicals can be used to disrupt interactions between host plants and cyst nematodes. Advances in RNAi techniques such as host-induced gene silencing to interfere with cyst nematode hatching and host location can also be exploited for development of synthetic resistant host cultivars.
Sammendrag
Plant-parasitic nematodes (PPN) cause significant yield reduction in commercial pineapple (Ananas comosus) worldwide. In Kenya, few nematode studies have been conducted, although the main commercial pineapple producer has sole dispensation to use Telone II (1,3-Dichloropropene) indicating the magnitude of the nematode problem. This study was conducted with the aim to investigate the population densities and diversity of nematodes in two commercial plantations with two contrasting management practices. We additionally assessed the influence of crop age and compared this with nearby smallholder pineapple production systems. Soil and root samples were collected from fields of different ages in each commercial plantation and from 29 smallholder fields. A total of 18 genera were associated with pineapple, with a relatively greater diversity found in smallholder than commercial farms. The most prevalent genus was Meloidogyne spp. (M. javanica) followed by Helicotylenchus spp., Tylenchus spp. and Aphelenchoides spp. PPN densities were higher in relatively older fields of 24 and 36 months than from fallow and 3-month-old fields. Regression analysis additionally demonstrated the rise of PPN densities with age of pineapple fields, especially Meloidogyne spp., while free-living nematode densities declined. This study provides an indication of the high level of PPN infection in pineapple in Kenya, which would constitute an important factor contributing to low yields. The study confirms an obvious need for pineapple producers to control PPN to improve crop yields.
Forfattere
James Kisaakye Hendrika Fourie Danny Coyne Laura Cortada Shirlyne Masinde Sevgan Subramanian Solveig HaukelandSammendrag
The banana weevil (BW), Cosmopolites sordidus, is the main coleopteran pest of banana, causing up to 100% yield loss. In this study, we screened 20 isolates of entomopathogenic fungi (EPF) for the management of BW. In the lab, eight Beauveria bassiana isolates caused >50% mortality of the adult BW, whereas Metarhizium anisopliae and Isaria fumosorosea isolates were less pathogenic. B. bassiana isolates ICIPE 648, ICIPE 660 and ICIPE 273 were the most pathogenic, killing ≥80% of adult BW. B. bassiana isolate ICIPE 622 yielded the highest spores per BW cadaver (1.84 × 108 spores), followed by ICIPE 660, ICIPE 273 and ICIPE 648—1.17 × 108, 3.8 × 107 and 3.6 × 107 spores, respectively. ICIPE 273 had the shortest LT50 (5.3 days) followed by ICIPE 648 (9.8 days) and 660 (11.1 days). Similarly, the LC50 values for the three isolates were 5.18 × 107, 5.49 × 107 and 5.2 × 107 spores mL−1, respectively. In the field, ICIPE 273 and ICIPE 648 had the highest (31.3%) and lowest (20.8%) pathogenicity, respectively. This study indicates that the B. bassiana isolates ICIPE 273, ICIPE 648 and ICIPE 660 are potential candidates for the environmentally sustainable management of BW.
Forfattere
Annika Pieterse Ben Rowson Louwrens Tiedt Antoinette P. Malan Solveig Haukeland Jenna L. RossSammendrag
A new species of Phasmarhabditis was isolated from the slug, Polytoxon robustum, from Nairobi, Kenya. The nematode was identified using morphological, morphometric, molecular and phylogenetic analyses. Phasmarhabditis kenyaensis n. sp. is characterised by an infective juvenile with the longest body length in the genus, measuring 1232 (1107-1336) μm, by the presence of males with a bursa bearing nine bilateral pairs of genital bursal papillae and one pair of papilliform phasmids flanking the tail, cephalate paired spicules, with an arc length of 71 (57-81) μm, as well as by females with a vulva located at the mid-body region and a conoid tail shape, with two phasmids located at ca 40% of the tail length. The molecular phylogeny of the new species, as inferred from its SSU (small subunit) rRNA gene, places P. kenyaensis n. sp. genetically close to undescribed phasmarhabditids from South Africa, suggesting an African grouping, while the D2-D3 (large ribosomal subunit) and ITS region analyses relate P. kenyaensis n. sp. to P. meridionalis, with weak bootstrap support. This is the third new Phasmarhabditis species described from the African continent, the new species bringing the total known complement of the genus to 14 species. A morphometric compendium to all species cultured in vivo is supplied.
Forfattere
Selamawit Araya Kidane Solveig Haukeland Beira H. Meressa Anne Kathrine Hvoslef-Eide Danny L. CoyneSammendrag
Enset (Ensete ventricosum), is a perennial herbaceous plant belonging to the family Musaceae, along with banana and plantain. Despite wild populations occurring in eastern, central and southern Africa, it is only in Ethiopia that the crop has been domesticated, where it is culturally and agriculturally symbolic as a food security crop. Although an under-researched orphan crop, enset serves as a staple food for about 20% of the Ethiopian population, comprising more than 20 million people, demonstrating its value in the country. Similar to banana and plantain, enset is heavily affected by plant-parasitic nematodes, with recent studies indicating record levels of infection by the root lesion nematode Pratylenchus goodeyi. Enset is propagated vegetatively using suckers that are purposely initiated from the mother corm. However, while banana and plantain suckers have proven to be a key source of nematode infection and spread, knowledge on the infection levels and role of enset suckers in nematode dissemination is lacking. Given the high levels of plant-parasitic nematodes reported in previous surveys, it is therefore speculated that planting material may act as a key source of nematode dissemination. To address this lack of information, we assessed enset planting material in four key enset growing zones in Ethiopia. A total of 340 enset sucker samples were collected from farmers and markets and analyzed for the presence of nematodes. Nematodes were extracted using a modified Baermann method over a period of 48 h. The root lesion nematode P. goodeyi was present in 100% of the samples, at various levels of infection. These conclusive results show that planting material is indeed a key source of nematode infection in enset, hence measures taken to ensure clean suckers for planting will certainly mitigate nematode infection and spread. The effect of nematode infection on yield and quality on enset remains to be investigated and would be a way forward to complement the nematode/disease studies conducted so far and add valuable knowledge to the current poorly known impact of pests and diseases.
Forfattere
Selamawit Araya Kidane Beira H. Meressa Solveig Haukeland Trine Hvoslef-Eide Danny L. CoyneSammendrag
Pratylenchus goodeyi appears to be the most prevalent nematode pest of enset in Ethiopia, where it can occur in extremely high densities. However, the damage to yield or how different enset cultivars react to the nematode has yet to be determined. The current study therefore sought to establish a first assessment of these reactions by enset to P. goodeyi infection. Determining pest resistant cultivars is an important task in developing management strategies. Our study evaluated nine enset cultivars to establish host response and identify potential sources of resistance. In addition, the pathogenicity of P. goodeyi was assessed on three enset cultivars. After 9 months’ growth, significant differences in final population densities (Pf) and reproduction factor (RF) were observed amongst the nine cultivars, with ‘Gefetanuwa’ the most susceptible (Pf = 25 799 and RF = 12.9), and similarly in a repeat experiment for 4.5 months (Pf = 126 534 and RF = 63.3). ‘Maziya’ and ‘Heila’ were the most resistant in the first experiment (Pf < 455 and RF < 0.2) as well as in the repeat, together with ‘Kellisa’ (Pf < 5255 and RF < 2.6). In the pathogenicity experiment four inoculum densities significantly affected the Pf and RF but not among the three cultivars ‘Maziya’, ‘Arkiya’ and ‘Heila’. This is the first known study to assess genotype reaction to P. goodeyi, which shows that there are significant differences in the reactions of different cultivars and that resistance appears to be present in enset.
Forfattere
Klaus. R Westphal Simone Bachleitner Manja M. Severinsen Mathias L. Brundtø Frederik T. Hansen Trine Sørensen Rasmus D. Wollenberg Erik Lysøe Lena Studt Jens L. Sørensen Teis E. Sondergaard Reinhard WimmerSammendrag
The plant pathogenic fungus Fusarium graminearum is known to produce a wide array of secondary metabolites during plant infection. This includes several nonribosomal peptides. Recently, the fusaoctaxin (NRPS5/9) and gramilin (NRPS8) gene clusters were shown to be induced by host interactions. To widen our understanding of this important pathogen, we investigated the involvement of the NRPS4 gene cluster during infection and oxidative and osmotic stress. Overexpression of NRPS4 led to the discovery of a new cyclic hexapeptide, fusahexin (1), with the amino acid sequence cyclo-(d-Ala-l-Leu-d-allo-Thr-l-Pro-d-Leu-l-Leu). The structural analyses revealed an unusual ether bond between a proline Cδ to Cβ of the preceding threonine resulting in an oxazine ring system. The comparative genomic analyses showed that the small gene cluster only encodes an ABC transporter in addition to the five-module nonribosomal peptide synthetase (NRPS). Based on the structure of fusahexin and the domain architecture of NRPS4, we propose a biosynthetic model in which the terminal module is used to incorporate two leucine units. So far, iterative use of NRPS modules has primarily been described for siderophore synthetases, which makes NRPS4 a rare example of a fungal nonsiderophore NRPS with distinct iterative module usage.
Forfattere
Annette Folkedal SchjøllSammendrag
Det er ikke registrert sammendrag
Intervju – Bekämpning av knäpparlarver - kräver ett helhetsgrepp
Annette Folkedal Schjøll, Åsa Rölin
Sammendrag
Det er ikke registrert sammendrag