Electrophysiological Responses of the Lepidopterous Stemborers Chilo partellus and Busseola fusca to Volatiles from Wild and Cultivated Host Plants

Abstract

The stemborers Chilo partellus and Busseola fusca are major pests of subsistence cereal farming in Africa. Volatiles released by two cultivated hosts, sorghum and maize (Sorghum bicolor and Zea mays), and two wild grass hosts, Pennisetum purpureum and Hyparrhenia tamba, were collected by air entrainment. Electrophysiologically active components in these samples were detected by coupled gas chromatography-electroantennography (GC-EAG), and the active peaks identified by gas chromatography-mass spectrometry. A total of 41 compounds were identified from the four plant species, all of which, as well as two unidentified compounds, elicited an electrophysiological response from one or both of the stemborers. The compounds included a number of green leaf volatiles and other aliphatic aldehydes, ketones, and esters, mono- and sesquiterpenoids, and some aromatic compounds. EAG studies with authentic samples, conducted at two discriminating doses for all compounds, and dose-response curves for 14 of the most highly EAG-active compounds, showed significant differences in relative responses between species. The compounds that elicited large responses in both species of moths included linalool, acetophenone, and 4-allylanisole, while a number of compounds such as the aliphatic aldehydes octanal, nonanal, and decanal elicited a large response in B. fusca, but a significantly smaller response in C. partellus. Furthermore, the wild hosts produced higher levels of physiologically active compounds compared with either of the cultivated hosts. These differences are discussed in relation to the differential attraction/oviposition of the two stemborers observed in the field and, particularly for eastern African small-scale farming systems, in the context of using a push-pull strategy for their control.

Volatile Attractants for the Common Bluebottle,Graphium sarpedon nipponum, from the Host,Cinnamomum camphora

“…Previous reports have indicated these aldehydes as EAG active compounds toward Lepidopterous stemborers, Chilo partellus and Busseola fusca, from their host plants, Zea mays, Sorgum bicolor, Pennisetum purpureum and Hyparrheria tamba. 29) More than 30 EAG active compounds, including nonanal and decanal, from Aesculus hippocastanum leaves fed on by larva of Cameraria ohridella have previously been reported. These two aldehydes were revealed to be oviposition inhibitors against adult C. ohridell.…”

Push—pull technology: a conservation agriculture approach for integrated management of insect pests, weeds and soil health in Africa

“…These companion crop plants release behaviour-modifying stimuli (semiochemicals) that manipulate the distribution and abundance of stemborers and beneficial insects for management of the pests (Hassanali et al, 2008) (Figure 1). The Napier grass trap crop produces significantly higher levels of green leaf volatile cues (chemicals), used by gravid stemborer females to locate host plants than maize or sorghum (Birkett et al, 2006). There is also an increase of approximately 100-fold in the amounts of these compounds produced in the first hour of nightfall (scotophase) by Napier grass , the period during which stemborer moths seek host plants for oviposition.…”

Insect-Pests and Their Management: Current Status and Future Need of Research in Quality Maize

“…The presence of mixtures of aliphatic aldehydes, ketones, alcohols, esters, as well as terpenoids and other aromatic compounds in the volatile emissions of corn leaves has been reported to be associated with orientation and ultimate recognition of host plants by the insects (Buttery and Ling 1984), and six plant volatiles, viz., octanal, nonanal, linalool, naphthalene, allylanisole, and eugenol, have been reported to mediate host location and oviposition by C. partellus females (Khan et al 2000;Birkett et al 2006). …”