Responses of stemborer Chilo partellus to volatiles emitted by maize landraces exposed to signal grass (Brachiaria brizantha)

Abstract

This study sought to evaluate the oviposition responses of Chilo partellus (Lepidoptera: Crambidae) on maize plants exposed to Brachiaria brizantha Stapf following oviposition by C. partellus and nonexposed maize. Two Kenyan maize landraces (Jowi and Nyamula), Latin America landrace (Cuba 91) and WH505 (hybrid variety) (control) were studied. The result demonstrated that C. partellus deposited a significantly lower number of eggs and egg batches on Nyamula, Jowi and Cuba 91 maize plants exposed to B. brizantha with C. partellus eggs compared to nonexposed ones and the exposed hybrid variety. This was because they emitted electrophysiologically active compounds such as (E)-4, 8-dimethyl-1, 3, 7-nonatriene, decanal, (E)-caryophyllene, linalool, linalool (plus nananal), E-β-fernesene, methyl salicylate and (3E, 7E)-4, 8, 12-trimethyl-1, 3, 7, 11-tri-decatetraene that deterred C. partellus from ovipositing more eggs on these plants. Therefore, herbivore-induced plant volatiles (HIPVs) of B. brizantha can be employed to protect the maize crop against C. partellus.

Associational Effects of Desmodium Intercropping on Maize Resistance and Secondary Metabolism

“…The increased consumption of neighbor-exposed SC Duma 43 plants suggests that the response of SC Duma 43 to above-ground neighbor cues may actually suppress direct resistance to larval feeding. This slightly contradicts the results of other recent studies, which have generally shown reduced oviposition by C. partellus and increased attraction of parasitoid wasps to maize exposed to intercrops such as Brachiaria brizantha (signal grass) and Mellinis minuti ora (molasses grass) (Tolosa et al 2019;Magara et al 2020). However, these other studies have not investigated the effect of neighborhood on larval feeding.…”

“…However, it is unclear what time scale is necessary for these soilmediated effects to develop. At the same time, there is growing evidence that mere proximity to some of the intercrops used in push-pull intercropping can reduce stemborer oviposition by directly altering the metabolic phenotype of maize plants (Tolosa et al 2019;Magara et al 2020). For example, maize plants growing next to signal grass (Brachiaria brizantha) were found to emit more volatiles, apparently resulting in reduced oviposition by C. partellus (Magara et al 2020).…”

Bioactive Volatiles From Push-Pull Companion Crops Repel Fall Armyworm and Attract Its Parasitoids

“…The volatiles identified here that are constitutively emitted by Desmodium and Brachiaria companion crops are similar to those emitted from maize upon S. frugiperda herbivory ( Pinto-Zevallos et al, 2016;De Lange et al, 2020). It is well documented that the volatiles constitutively emitted from Desmodium and Brachiaria companion crops, i.e., (E)-2hexenal, (Z)-3-hexenyl acetate, (E)-β-ocimene, (S)-linalool, DMNT, MeSA, indole, β-caryophyllene, (E)-β-farnesene, and TMTT, also serve as herbivore-induced plant volatiles (HIPVs) in maize and repel herbivores and attract their natural enemies (Turlings et al, 1991;De Moraes et al, 1998Kessler and Baldwin, 2001;Tamiru et al, 2015;Richter et al, 2016;Magara et al, 2020). It seems plausible that emission of these volatile compounds can explain the reduced infestation of S. frugiperda in maize intercropped with companion crops.…”

Wild Progenitor and Landraces Led Genetic Gain in the Modern-Day Maize (Zea mays L.)

“…Palomero Toluqueno, a landrace of popcorn reported to have resistance to the maize weevil [67], few Carrebian landraces possess resistance to larger grain borer [68]. Two Kenyan maize landraces (Jowi and Nyamula) and one Latin American landrace (Cuba 91) shown a lower number of eggs and egg batches deposition of C. partellus due to production of herbivore-induced plant volatiles (HIPVs) [69,70]. The fall armyworm Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) is one of the most damaging maize production pests in tropical areas.…”