Identification of repellents from four non-host Asteraceae plants for the root knot nematode, Meloidogyne incognita

Authors: MWAMBA, SYDNEY - African Insect Science For Food And Health (ICIPE); KIHIKA-OPANDA, RUTH - African Insect Science For Food And Health (ICIPE); MURUNGI, LUCY - Jomo Kenyatta University; LOSENGE, TUROOP - Jomo Kenyatta University; Beck, John; TORTO, BALDWYN - African Insect Science For Food And Health (ICIPE)

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2021
Publication Date: 12/9/2021
Citation: Mwamba, S., Kihika-Opanda, R., Murungi, L.K., Losenge, T., Beck, J.J., Torto, B. 2021. Identification of repellents from four non-host Asteraceae plants for the root knot nematode, Meloidogyne incognita. Journal of Agricultural and Food Chemistry. 69, 15145-15156. https://doi.org/10.1021/acs.jafc.1c06500.
DOI: https://doi.org/10.1021/acs.jafc.1c06500

Interpretive Summary: Plant parasitic nematodes (PPNs) are small worm-like animals that can incur serious damage to agricultural commodities. Control of PPNs is difficult and can require the use of pesticides. A USDA-ARS scientists at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL and collaborators at the International Centre for Insect Physiology and Ecology in Nairobi, Kenya investigated the underground odors of several plants known to inhibit the parasitic nematode Meloigodyne incognita and identified two odors that repelled the PPNs, and one odor that attracted the PPNs. The ability to repel PPNs from agricultural commodities would allow growers to protect their crops and safely increase their yields while avoiding the use of pesticides.

Technical Abstract: Olfactory cues guide plant parasitic nematodes (PPNs) to their host plants. We tested the hypothesis that non-host plant root volatiles repel PPNs. To achieve this, we compared the olfactory responses of infective juveniles (J2s) of the PPN Meloidogyne incognita to four non-host Asteraceae plants, namely, black-jack (Bidens pilosa), pyrethrum (Chrysanthemum cinerariifolium), marigold (Tagetes minuta), and sweet wormwood (Artemisia annua), traditionally used in sub-Saharan Africa for the management of PPNs. Chemical analysis by coupled gas chromatography-mass spectrometry (GC/MS) combined with random forest analysis, followed by behavioral assays, identified the repellents in the root volatiles of B. pilosa, T. minuta, and A. annua as (E)- ß-farnesene and 1,8-cineole, whereas camphor was attractive. In contrast, random forest analysis predicted repellents for C. cinerariifolium and A. annua as ß-patchoulene and isopropyl hexadecanoate. Our results suggested that terpenoids generally account for the repellency of non-host Asteraceae plants used in PPN management.