Sobhy, IS, Tamiru, A, Chiriboga Morales, X, Nyagol, D, Cheruiyot, D, Chidawanyika, F, Subramanian, S, Midega, CAO, Bruce, TJA and Khan, ZR (2022) Bioactive Volatiles From Push-Pull Companion Crops Repel Fall Armyworm and Attract Its Parasitoids. Frontiers in Ecology and Evolution, 10. ISSN 2296-701X

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Fall armyworm, Spodoptera frugiperda, is a serious invasive pest in Africa but "Push-Pull" companion cropping can substantially reduce infestation. Here, we elucidate the underpinning chemical ecology mechanisms. We hypothesized that companion crop volatiles repel herbivores (push) while attracting natural enemies (pull). Headspace volatiles collected from companion plants (Desmodium intortum, Desmodium uncinatum, Brachiaria Mulato II) were used in bioassays and electrophysiological recordings with S. frugiperda and parasitoid wasps. Insect populations, plant damage and herbivore parasitism were assessed in field plots. Coupled GC-electroantennogram (GC-EAG) recordings showed robust responses to certain aromatic and terpenoid volatile compounds. In wind tunnel bioassays, maize volatiles mixed with Desmodium volatiles were less attractive to moths than maize alone. In oviposition bioassays, S. frugiperda laid significantly fewer eggs on maize when Desmodium volatiles were present. Conversely, in an olfactometer bioassay, parasitoid wasps were attracted to the scent of both Desmodium spp. (intercrop) and the Brachiaria border crop. Our data provide evidence of the mechanisms underpinning reduced S. frugiperda infestation in the Push-Pull companion cropping system, i.e., volatiles from companion crops repel S. frugiperda while attracting its parasitoid natural enemies. These findings explain why Push-Pull field plots had fewer S. frugiperda larvae and lower crop damage than monocropped maize.

Item Type: Article
Additional Information: © 2022 Sobhy, Tamiru, Chiriboga Morales, Nyagol, Cheruiyot, Chidawanyika, Subramanian, Midega, Bruce and Khan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Uncontrolled Keywords: volatiles; tritrophic interactions; Push-Pull; maize; herbivory; companion crops; chemical ecology; behavioral response
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Q Science > QD Chemistry > QD415 Biochemistry
S Agriculture > S Agriculture (General)
Divisions: Faculty of Natural Sciences > School of Life Sciences
Depositing User: Symplectic
Date Deposited: 24 May 2022 14:03
Last Modified: 15 Jun 2022 10:05

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