Promising leads for the control of root-knot nematodes

A study by icipe and partners has provided promising leads for the development of ecofriendly strategies to control root-knot nematodes; highly destructive, soil dwelling, microscopic worms that cause up to 100% yield loss in important crops like tomato, pepper and African leafy vegetables.

“Specifically, our research identified the chemical signals involved in the interaction between southern root-knot nematodes, Meloidogyne incognita Kofoid and White (Chitwood), one of the most damaging species, and a variety of pepper plants grown in East Africa. Although previous studies have shown that roots of host plants may attract or repel nematodes, this is the first time that the mediating chemicals have been established,” explains Ruth Kihika, who conducted the research as part of her MSc studies at icipe

The findings, published in Scientific Reports (an online multidisciplinary, open access journal from the publishers of the highly prestigious Nature journal), create new opportunities for breeding peppers that are resistant to root-knot nematodes.


The results lay the basis to explore specific ways to suppress production of chemicals  that attract nematodes, or to incorporate genes responsible for the emission of chemicals that repel the pests. These strategies would enable protection of the plants against infection by root-knot nematodes without altering other characteristics, such as pepper flavour. From a scientific point of view, the research provides new insights towards linking molecular methods with biochemical processes for plant protection against nematodes.

Root-knot nematodes obtain their name from their ability to infect and cause galls (swellings or knots) in their host plants.The nematodes feed and develop in the galls, in the process impeding nutrient and water uptake by the host plant resulting in poor growth and crop yield. Additionally, such damage increases the severity of opportunistic infections from other soil pathogens. Several methods, including crop rotation, use of resistant cultivars, biological control and nematicides are used to control root-knot nematodes. Fumigant nematicides, the most promising, are no longer used due to their ozone-depleting properties. As such, there is an urgent need for sustainable solutions to control root-knot nematodes.


Notes for Editors

Publication: Kihika, R., Murungi, L.K., Coyne, D., Ng’ang’a, M., Hassanali, A., Teal, P. E. A. & Torto, B. (2017) Parasitic nematode Meloidogyne incognita interactions with di erent Capsicum annum cultivars reveal the chemical constituents modulating root herbivory. Scientific Reports, 7: 2903. DOI:10.1038/s41598-017-02379-8. Available at

Corresponding author: Prof. Baldwyn Torto –; Tel +254 20 832000

Funding for this research was provided by the United States Department of Agriculture/Agricultural Research Service, Grant No. 58-6615-3-011 F; and by icipe core donors: UK Aid from the UK government; the Swiss Agency for Development Cooperation (SDC); the Swedish International Agency for Development Cooperation (Sida) and the Government of Kenya. The views expressed herein do not necessarily reflect the official opinion of the donors.

Research collaborators: International Centre of Insect Physiology and Ecology (Behavioural and Chemical Ecology Unit); Kenyatta University, Kenya; Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya; International Institute of Tropical Agriculture (IITA); United States Department of Agriculture/Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology (USDA/ARS-CMAVE).