Analysis of volatile phytochemical for wild non-host plant, melinis minutiflora P. Beav., and wild host plant pennisetum purpureum(K) sihumach of Chilo Portellus (swinhoe)
Mbuthia, Kimani S.
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Semiochemicals that could be involved in host and non-host plant selection by Chilo partellus (Swinhoe) were identified from volatiles released by wild host plant, Pennisetum purpureum (K) Schumach. And wild non-host plant, Melinis Minutiflora P Beauv. Volatiles were trapped using Prapak Q adsobent for 24 hrs and analyzed using GC, GC-MS, and GC co-injection with authentic samples. Compounds confirmed to be present in the headspace of P purpureum were toluene, p-xylene, -pinene, -pinene, (Z)-3-hexenyl acetate, (+)-2-carene, decanal, -caryophyllene and -humulene. On the other hand, headspace volatiles of M. minutiflora contained hexanal, a-pinene, (E)-v-ocimene, terpinolene, 4, 8-dimethylnona-1,3,7-rriene, methyl salicylate, -cubebene, -ylangene, -cubebene, -caryophyllene and a-humulene. The latter results compared significantly with those of the field trapping using reverse-phase adsorbent. However, the headspace volatiles of M. minutiflora varied significantly from its steam distilled oil which contained toluene, hexanal, 3-hexenol, 2-heptanone, heptanal, (E)-2-octenal, nonanal, methyl salicylate, decanal, -caryophyllene and -humulene. A GC comparison of the airborne volatiles from M. minutiflora recovered from activated charcoal, Porapak Q and reverse phase traps shosed no discernible qualitative differences in the components present. Electrophysiologically active compounds located by GC-EAG were identified as: sabinene, 2-pentylfuran, (E)--ocimene, terpinolene, 4,8-dimethylnona-1, 3,7-triene, -cubebene and -caryophyllene. These compounds have been found to elicit behaviour in some important phytophagous insects. Hence, subtractive behaviour assays could be carried out to determine the attractive and repulsive substances for oviposition and feeding behaviour. This can lead to an alternative method of controlling and managing this insect pest.