Distribution and diversity of alternate hosts of Maruca vitrata Fabricius in three West African countries

Authors: ADDAE, PRINCE - African Agricultural Technology Foundatin; BRUCE, Y. ANANI - International Maize & Wheat Improvement Center (CIMMYT); UTONO, ILIYASU - Institute For Agricultural Research, Samaru; ABUDULAI, MUMUNI - Savanna Agricultural Research; TRAORE, FOURSSENI - Institute Of Environmental And Agricultural Research - Burkina Faso (FORMERLY: UPPER VOLTA); ISHIYAKU, MOHAMMAD - Institute For Agricultural Research, Samaru; ADAMU, RABIU - Institute For Agricultural Research, Samaru; SEIDU, AHMED - Savanna Agricultural Research; BATIENO, BENOIT - Institute Of Environmental And Agricultural Research - Burkina Faso (FORMERLY: UPPER VOLTA); NWANKWO, ONYEKACHI - African Agricultural Technology Foundatin; BA, MALICK - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - Nigeria; ADAZEBRA, GLORIA - Savanna Agricultural Research; TIGNEGRE, JEAN BAPTISTE - University Of Bamako; DABIRE-BINSO, CLEMENTINE - Institute Of Environmental And Agricultural Research - Burkina Faso (FORMERLY: UPPER VOLTA); HUESING, JOSEPH - Huesing Agricultural And Educational Consulting Llc; Hellmich Ii, Richard; PITTENDRIGH, BARRY - Purdue University; TAMO, MANUELE - National Science And Technology University Of Benin

Submitted to: International Journal of Tropical Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2021
Publication Date: 4/29/2021
Citation: Addae, P.C., Bruce, Y., Utono, I.M., Abudulai, M., Traore, F., Ishiyaku, M.F., Adamu, R.S., Seidu, A., Batieno, B.J., Nwankwo, O.F., Ba, M.N., Adazebra, G.A., Tignegre, J., Dabire-Binso, C.L., Huesing, J.E., Hellmich II, R.L., Pittendrigh, B.R., Tamo, M. 2021. Distribution and diversity of alternate hosts of Maruca vitrata Fabricius in three West African countries. International Journal of Tropical Insect Science. https://doi.org/10.1007/s42690-021-00470-2.
DOI: https://doi.org/10.1007/s42690-021-00470-2

Interpretive Summary: Insect predation, predominately from the legume pod borer, Maruca vitrata,(moth pest) flower thrips and a complex of pod-sucking bugs, is a major yield-limiting factor in West African cowpea production. Dramatic increases in yield are shown when the legume pod borer is controlled with insecticides. However, availability, costs, and safety considerations limit pesticides as a viable option for boosting cowpea production. Development of Bacillus thuringiensis (Bt) cowpea through genetic engineering to control the legume pod borer is a promising approach to cowpea improvement. There are concerns, however, that the legume pod borer could become resistant to Bt cowpea. An insect resistant management (IRM) strategy that uses high-dose Bt cowpea and refuge is planned. There is a question, however, about whether there are alternate host species that could contribute unselected refuge moths to the IRM strategy. A survey was conducted to identify alternate host species for legume pod borer that could serve as refuge for Podborer Resistant (Bt) cowpea in West Africa. Many sites including, 25 in Tolon district in Ghana, 44 sites in Bunkure and Bomo districts in Nigeria and 43 sites in Bobo Duilasso and Ziniare districts in Burkina Faso were surveyed. Results suggest the abundance of alternate hosts with overlapping flowering patterns with the cowpea crop in most locations, would allow development of ample numbers of Bt susceptible legume pod borer that would mate with potential resistant legume pod borer and deter resistance development. This approach concurs with the high-dose/refuge IRM strategy. Improving the productivity of cowpea would enhance food availability and security in West Africa.

Technical Abstract: The evolution of resistance to the Bt toxins by insect pests is a major concern in application of Bt technology. However, the rate of evolution of this resistance can be slowed or stopped through the use of appropriate and integrated insect resistance management (IRM) strategies. A survey was conducted to identify alternate host species for Maruca vitrata that will serve as refuge for Podborer Resistant (Bt) cowpea in West Africa. Many sites including, 25 in Tolon district in Ghana, 44 sites in Bunkure and Bomo districts in Nigeria and 43 sites in Bobo Duilasso and Ziniare districts in Burkina Faso were surveyed. Alternative hosts of M. vitrata were identified by first observing all plant species belonging to Fabaceae family within the sampling sites, plants showing symptoms of M. vitrata damage on terminal shoots, flower buds, flowers and pods were collected and put in glass jars and taken to the laboratory for dissection to reveal M. vitrata larvae and reared adult moths. The alternate host plants, including Crotolaria, Sesbania, Tephrosia, Vigna, Senna and Centrosema species, were found in many sites within each district. Flowering and pod development of most of these plants overlapped with flowering and pod development of the nearby (~200m) cowpea crop. Abundance of these wild hosts and overlapping flowering patterns with the cowpea crop in most locations should develop ample numbers of Bt susceptible Maruca vitrata that will mate with potential resistant M. vitrata and deter resistance development. This approach concurs with the high-dose/refuge IRM strategy. An IRM strategy that includes the alternate hosts as refuge, seed deployment patterns, monitoring, and grower’s compliance should be developed to protect Bt cowpea from resistant maruca podborer.