icipe Governing Council honours outstanding young scholars
During its annual general meeting held in Nairobi, Kenya, at the end of October, the icipe Governing Council, will consists of globally reknowned scientists, honoured six outstanding postgraduate scholars, currently undertaking their research at the Centre.
Best published paper category
Rosaline Wanjiru Macharia
icipe supervisor – Dr. Daniel Masiga
Macharia R., Mireji P., Murungi E., Murilla G., Christoffels A., Aksoy S. and Masiga D.K. (2016) Genome-wide comparative analysis of chemosensory gene families in five tsetse fly species. PLOS Neglected Tropical Diseases 10, e0004421.doi:0004410.0001371/journal.pntd.0004421
Contribution to science:
This paper describes the identification and comparative analyses of chemosensory proteins in five tsetse fly species. Their putative roles were elucidated based on close insect relatives such as fruit fly, housefly and mosquitoes. The paper further explains how some of the identified genes could be potentially used to improve tsetse control strategies. This study is the first of its kind in comparing chemosensory genes among tsetse species based on genomic data. The study applied bioinformatics tools to identify chemosensory genes and compare them with those of closely related species. It also reports for the first time the influence of natural selection forces on evolution of tsetse fly chemosensory genes. This work contributes to the body of knowledge on tsetse chemosensation and ecology. It provides baseline information useful for improving tsetse control. Understanding the role of genes responsible for host identification is crucial in management of disease vectors. Tsetse control is a primary mandate for icipe with an aim of improving the livelihoods of the African communities afflicted by African trypanosomiasis. This study contributes towards knowledge on proteins that can be used as targets for enhancing control through use of attractants and/or repellents. The results of this study thus form a basis for improving tsetse control. This will enhance the health of the African populations together with their livestock. This will in turn increase animal productivity, food security and alleviate poverty among the affected communities. In conclusion, the paper recommends on further functional research on the genes as well as studying the signalling mechanism involved in odour reception by tsetse flies.
This research was conducted with funding from the German Academic Exchange Service (DAAD) through icipe’s African Regional Postgraduate Programme in Insect Science (ARPPIS). Additionally, research reported in this publication was also supported by the National Human Genome Research Institute of the National Institutes of Health under Award Number U41HG006941. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The Grant Award was to University of Cape Town, H3ABionet Africa Project of which icipe is a sub-grantee.
Rosaline is registered at University of Western Cape, South Africa.
Matilda Wangeci Gikonyo (MSc scholar)
icipe Mentors – Dr Subramanian Sevgan, Dr Fathiya Khamis and Dr Saliou Niassy
Gikonyo M. W., Niassy S., Moritz G.B., Khamis F. M., Magiri E. and Subramanian S. (2016) Resolving the taxonomic status of Frankliniella schultzei (Thysanoptera: Thripidae) colour forms in Kenya – A morphological-, biological-, molecular -and ecological-based approach. International Journal of Tropical Insect Science, 1–14. doi:10.1017/S1742758416000126.
Contribution to science:
The paper describes an exceptional case of speciation within the thrips genus Frankliniella whereby two morphotypes initially described as one species were proven to be two different species. The two forms present similar morphological features, share common geographical habitat and even share the same host plants. This justified their grouping as one species; Frankliniella schultzei. Earlier efforts to characterise such closely similar species/morphotypes have either solely depended on either morphological approaches or molecular methods alone. One major constraint of morphological identification is its dependence on human expertise and that it often overlooks cryptic features, which are common in many insect groups. Morphological identification of thrips species is also limited to adults, as larval stages cannot be easily distinguished. On the other hand, molecular identification is solely dependent on genetic sequence databases, which bring in an element of ambiguity, if a particular species is not represented in the reference databases. Hence, molecular identification can function only as an identification tool, which needs to be complemented by other methods for accurate identification. This research study employed modern molecular tools such as the Restriction Fragment Length Polymorphism of the internal transcribed spacer region (ITS-RFLP) analysis to complement morphological and biological methods in distinguishing the two colour forms. This produced a more accurate distinction than previously described. Other biological factors which are often neglected, such as, interbreeding potential, host plant associations and geographic distribution were also taken into account in this study. Therefore, thanks to morphological characteristics, molecular differences (ITS-RFLP), biological features (interbreeding potential) and ecological factors (geographical and host plant association) that we defined; we resolved the taxonomic status of the two colour forms of F. schultzei beyond ambiguity. Both the colour forms of F. schultzei are pest of a wide array of crops, with significant differences in their ability to transmit Tospoviruses and more recently the Maize Chlorotic Mottle Virus. Results from this study in terms of accurate identification, will help in designing appropriate integrated pest management tools and strategies aimed at a specific colour form. This would immensely assist in avoiding the degradation of the environment and elimination of beneficial insects by broad-spectrum chemical insecticides. In the long run, such appropriate IPM strategies are likely to significantly reduce the crop productivity losses associated with the two species and aid in addressing the problems of poverty and ecological sustainability faced by farmers in Africa. The results of this study will also strengthen the capacity of quarantine agencies in accurate diagnostics and monitoring of distribution of the two colour forms.
The research was conducted within the framework of an icipe project Grant Contract No. 81141840 financed by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) on behalf of the Government of the Federal Republic of Germany.
Matilda is registered at Jomo Kenyatta University of Agriculture and Technology, Kenya.
Mercy Mumbi Murigu (MSc scholar)
icipe Mentors -- Dr Nguya Maniania, Dr Sunday Ekesi and Dr Paulin Nana
Murigu M., Nana P., Waruiru R.M., Nga'nga' C.J., Ekesi S. and Maniania N.K. (2016) Laboratory and field evaluation of entomopathogenic fungi for the control of amitraz-resistant and susceptible strains of Rhipicephalus decoloratus. Veterinary Parasitology 225, 12–18.
Contribution to science:
Ticks and tick-borne diseases (TBDs) represent a major constrain to livestock production in tropical and subtropical regions. The most devastating species in East Africa region include Rhipicephalus appendiculatus, Amblyomma variegatum and Rhipicephalus decoloratus. R. decoloratus are vectors of anaplasmosis caused by Anaplasma marginale and babesiosis caused by Babesia bigemina in cattle. Both diseases cause high production losses and frequently lead to death. In the absence of effective vaccines against anaplasmosis and babesiosis, control of the vector remains the best option. Tick control is mainly based on the use of chemical acaricides such as amitraz, pyrethroids and organophosphates. However, chemical control has resulted in toxicological and environmental hazards as well as unselective killing including non-target organisms. More importantly, ticks have developed resistance to various classes of compounds. This has prompted the search for alternative tick control measures. The use of entomopathogenic fungi (EPF) is among the strategies being considered. Three mycoacaricides based on Metarhizium anisopliae have been developed and commercialized for the control of Ixodid ticks. An integrated icipe tick management strategy using EPF as core component could address the problem of acaricide resistance in ticks. The objectives of the present study were to screen fungal isolates of B. bassiana and M. anisopliae for their virulence against amitraz-resistant and amitraz-susceptible strains of R. decoloratus, to evaluate the compatibility of selected fungal isolate with acaricide and to evaluate the field efficacy on-host ticks. In the present study, the author investigated the pathogenicity of different fungal isolates against amitraz-resistant and amitraz-susceptible strains of R. decoloratus and concluded that there was no discrimination between the two strains of ticks. The study also demonstrated that ICIPE 7 which was confirmed as the most pathogenic fungal isolate against the R. decoloratus ticks was also compatible with amitraz and application of this isolate on cattle as a spray resulted in significant reduction of on-host ticks. The fungal isolate, ICIPE 7 can be developed as mycoacaricide which will be an alternative method of tick control that will reduce the frequency of chemical acaricide use and the need for treatment for tick borne diseases; reduce the development of chemical resistance in some tick populations; avoid food and environmental contamination and is cheaper than synthetic acaricides which are expensive. The use of EPF in tick control will be a viable strategy, it will lower the cost of buying acaricide because the frequency of acaricide application will be reduced thus lowering the cost of production.
This research has been funded by UK Aid from the UK Government; however the views expressed do not necessarily reflect the UK Government’s official policies.
Mercy is registered at the University of Nairobi, Kenya.
Best poster category
Pamela Ochungo (PhD scholar)
Poster: “Landscape Setup and Honey Bee Colony Integrity: A Case Study of Mwingi, Eastern Kenya”
Pamela A. Ochungo*, Tobias Landmann, Eliud Muli and Ruan Veldtman
International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya; and *Stellenbosch University, Stellenbosch, South Africa
The poster discusses the importance of understanding the linkages between landscape characteristics and honey bee colony integrity. In Africa, land is being transformed for agricultural expansion, which impedes colony health since the resource base is either removed or contaminated. Whereas a significant proportion of all the food crops that we rely on depend on honey bee pollination, there is a dearth of knowledge on how honey bee foraging, productivity and colony strength will be affected by changing land use and land cover. The poster describes a multidisciplinary approach whereby on one hand, earth observation techniques are being used for mapping landscape patterns up to the vegetation community level and on the other hand pollen characteristics, colony strength measurements and hive productivity analysis are being applied in the study.
This research was conducted with funding from the German Academic Exchange Service (DAAD) through icipe’s African Regional Postgraduate Programme in Insect Science (ARPPIS), the European Union (EU), and icipe core funding provided by UK Aid from the UK Government, Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), Federal Ministry for Economic Cooperation and Development (BMZ), Germany, and the Kenyan Government. The views expressed herein do not necessarily reflect the official opinion of the donors.
Beritah Mutune (MSc scholar)
Poster: Fungal endophytes as promising tools for the management of bean stem maggot Ophiomyia phaseoli on beans Phaseolus vulgaris
Beritah Mutune*, Sunday Ekesi, Saliou Niassy, Viviene Matiru, Christine Bii and Nguya K. Maniania
International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya; and *Jomo Kenyatta University of Agriculture and Technology, Juja, Kenya
The poster demonstrates the use of fungal endophytes for the control of bean stem maggot (BSM) Ophiomyia spp., which is a menace to bean farmers as it attacks the seedlings once they sprout from the ground. The poster also highlights the use of fungal entomopathogens as endophytes to control BSM. The fungal isolates were able to endophytically colonize the bean plants and the effect of inoculation on BSM feeding and oviposition, pupation and adult emergence was assessed. BSM feeding and oviposition was significantly reduced in fungus-inoculated bean plants, which in turn affected pupation and adult emergence. As illustrated in the poster, Metarhizium anisopliae isolate, ICIPE 20 outperformed the other isolates in interfering with the BSM life cycle and can be effectively developed into a biopesticide. The poster clearly demonstrates that fungal endophytes can be considered as promising tool for the management of BSM globally which can be used as an alternative to chemical control. This promotes bean cultivation, which generates food and income, alleviating poverty and promoting food security.
This work was conducted with funding from the World Federation of Scientists, icipe Innovative Seed Grant, and icipe core funding provided by UK Aid from the UK Government, Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), Federal Ministry for Economic Cooperation and Development (BMZ), Germany, and the Kenyan Government. The views expressed herein do not necessarily reflect the official opinion of the donors.
Nelly Ndungu (PhD scholar)
Poster: Transcriptome Comparison Between Newly Emerged Queen and Worker Bees of Stingless Bee Hypotrigona gribodoi
Ndungu, Nelly*, Henson, S., Kiatoko, N., Ahmed, Y., Pirk, C., Masiga, D and Raina, S.
International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya; and *Social Insect Research Group, University of Pretoria, South Africa.
The poster discusses the fourth objective of the scholar’s PhD study. Stingless bees are important ecologically and in improving livelihood sustainability through hive products. Stingless bees are considered as an alternative pollinator to honey bee due to similarity in foraging traits. Contrary to the honeybee, the main challenge in stingless bee domestication is the mass production of queens. One way to achieve this is by studying caste differentiation to understand the basis for caste differentiation. This is the first study to report queen-worker gene differentiation in an African stingless bee species.
This work was conducted with funding from the German Academic Exchange Service (DAAD) through icipe’s African Regional Postgraduate Programme in Insect Science (ARPPIS), European Union (EU), and icipe core funding provided by UK Aid from the UK Government, Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), Federal Ministry for Economic Cooperation and Development (BMZ), Germany, and the Kenyan Government. The views expressed herein do not necessarily reflect the official opinion of the donors.