Program Chair: Sophie Bouvaine
A large number of viruses responsible for devastating diseases of plants, humans, and animals rely exclusively on insect vectors for their dissemination between hosts. Modes of transmission vary between systems; however, the spread of these viruses always requires specific interactions between the virus and its vector. This knowledge is crucial to develop vector control methods that ultimately curb the spread of diseases. In this session, we will explore in parallel some recent progress in virus-vector interaction research for both plant and animal viruses and review their potential applications.
Climate smart agriculture strategies in Latin America
Whiteflies, especially the sweetpotato whitefly Bemisia tabaci, are among the most successful plant virus vectors and transmit more than 400 viruses. Virus passage through whitefly tissues has been considered for many years, a passive process in which no or minimal whitefly responses occur. This assertation was mainly attributed to the non-replicative nature of whitefly-transmitted viruses. B. tabaci transmits DNA and RNA viruses from different genera. RNA viruses are non-circulative, and cause no or minimal responses in the whitefly, due to minimal interactions with cellular tissues. On the other hand, circulative viruses, which mainly belong to ssDNA viruses of the genus begomovirus, have been shown to breach cellular membranes in several tissues, and exploit molecular and cellular machineries for their passage, including interactions with whitefly endosymbiotic bacteria. The demonstration that Tomato yellow leaf curl virus (TYLCV) and other begomoviruses were transovarially and sexually transmitted, led to reinvestigating their replication in B. tabaci. Replication, although still controversial, was demonstrated through a series of studies. In these studies, induction of antiviral and immune responses such as apoptosis in whitefly tissues by TYLCV, exploiting whitefly proteins for movement, and trafficking in whitefly cells using the early endosome and endo-exocytosis, have all shown that under certain conditions this virus is able to replicate in whitefly cells. In conclusion, the last 30 years of research in the field of whitefly-begomovirus interactions have witnessed a significant leap in our understanding this system, and have shown that these interactions are not naive, as many used to think.
Dr. Murad Ghanim
Department of Entomology, the Volcani Center
Rishon LeZion, Israel
Dr. Murad Ghanim is a senior scientist at the Volcani Center in Israel and adjunct professor of Entomology in the Hebrew University of Jerusalem, Israel. He graduated from the Hebrew University of Jerusalem focusing his research on the molecular interactions between whiteflies and begomoviruses. He completed a three-year postdoc at Yale University School of Medicine in the USA, and focused his research during this period on Drosophila melanogaster genomics and early embryonic development, after which he joined the Department of Entomology of the Volcani Center in Israel. His research focuses now on the interactions between insect vectors of plant pathogens including whiteflies and psyllids with plant pathogenic viruses and bacteria, and factors inside insect vectors that influence pathogen transmission, such as insect proteins and endosymbiotic bacteria. His other research interests include the development of new and biorational pesticides with the industry and screening for active natural compounds against insect pests. He has published more than 160 ISI papers in peer‐reviewed journals.
Improving entomologic surveillance of dengue
Dengue is an arboviral disease of global public health significance primarily spread by the mosquito Aedes aegypti in tropics and sub-tropical regions. The burden of the disease in humans can be minimized through active surveillance of the causative virus (dengue virus) in the mosquito vectors. This entails monitoring of vector populations and tracking of viral activity in them. Thus, trap sensitivity becomes an important component of mosquito-based dengue surveillance and critical in determining spatio-temporal changes in vector density, distribution, and risk of dengue virus transmission. This presentation will focus on the use of cost-effective monitoring tools to assess population dynamics of Ae. aegypti, and application of molecular and virological approaches to depict their vertebrate hosts and viral associations in an urban setting in Kenya.
Dr. David P. Tchouassi
International Centre of Insect Physiology and Ecology
David P. Tchouassi received his PhD from the University of Pretoria, South Africa, through a joint PhD program (ARPPIS) with the International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya, in 2013. He worked on Rift Valley fever vector chemical ecology and genetics for his doctoral studies and later as a postdoctoral Fellow at icipe (2013-2015). He is a Senior Scientist in the Human Health Theme at icipe having previously served as a Research Scientist (2015-2022). His interest is in understanding host-vector-pathogen interactions, and how these govern transmission ecology and shape epidemiology of malaria and arboviral diseases. Aspects of his work explore chemical communication of disease vectors to develop eco-friendly tools for disease surveillance and control.
The cassava whitefly, Bemisia tabaci: Unravelling the genetic diversity and efforts towards IPM for vector control
Cassava Bemisia tabaci whitefly damages cassava through feeding and transmission of the viruses that cause cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) in Africa. High whitefly populations of this pest are associated with rapid spread and severe epidemics of CMD and CBSD. There is current rapid spread of CBSD in several parts of central and southern Africa, in particular including eastern Democratic Republic of Congo and north-western Zambia. Strategies for effective whitefly management depend on a thorough understanding of genetic diversity of these insect vectors. SNP-genotyping through NextRAD sequencing revealed the existence of six major genetic haplogroups of this pest, all of which are connected through gene flow. This robust technique also confirmed the routinely used mtCOI sequencing technique is ineffective at distinguishing major genetic groupings of the cassava whitefly. The SNP data were used to develop a KASP genotyping assay which currently distinguishes the six groups under standard molecular laboratory conditions hence eliminating the cost and time associated with sequencing. Efforts are ongoing to develop an IPM strategy for management of whiteflies in cassava. Two potential control techniques – cutting dipping in insecticides (Flupyradifurone) and spraying of commercial entomopathogenic fungal biopesticides (Lecatech and Mycotal) – have been evaluated under field conditions. Cutting dips reduced adult whiteflies for six months following planting by an average of 40% and nymphs by 65%. The dips reduced CMD incidence by 16% and increased root yield by 49% in treated compared to control plots. The biopesticides reduced whitefly nymph abundance by an average of 70%. The findings from these studies show that insecticide cutting dips and entomopathogenic fungal biopesticides are effective at reducing cassava whitefly populations, and both techniques could be incorporated as components of IPM against this pest.
Dr. Everlyne Wosula
International Institute of Tropical Agriculture (IITA)
Dar es Salaam, Tanzania
Everlyne Wosula is a Vector Entomologist at the International Institute of Tropical Agriculture (IITA) Eastern Africa Hub, Dar es Salaam, Tanzania. She has over 10 years of experience working on arthropod vectors of plant viruses and the dynamics of virus transmission. Her research is on diagnostic tools for molecular characterization, and novel techniques for management of cassava Bemisia tabaci whiteflies, vectors of cassava begomoviruses and ipomoviruses. Main themes of her research include: the efficacy of botanical oils, entomopathogens, soft chemistry insecticides and host plant resistance in controlling whiteflies; and the development and testing of IPM packages for managing cassava pests. Her other area of interest is researching the impact of climate change on vectors, viruses and the efficacy of control strategies.