Electroantennogram response of the coconut pest, Rhynchophorus ferrugineus (Coleoptera:Curculionidae) to alcohols

Abstract

: The coconut pest Rhynchophonrr J2mrgineu.s E, shows short range attraction to coconut sap,whose volatile constituents consist mainly of short chain alcohols. In this study, electrophysiological responses of male and female antennae to four alcohols in coconut sap, viz. ethyl, n-propyl, n-butyl and n-pentyl alcohols were recorded. Pentanol, which constitutes a major portion of the coconut sap elicited the greatest response in the antennae of both male and female IR. To compare the activities of the above alcohols with C6 to CI0 n-alcohol, EAGs of bexanol upto decanol were also recorded under the similar conditions. Results showed that ;he activity of pentanol was still the highest in the series, while that of hexanol (EAGEAG,,, 0.83, SD* 0.16) was not significantly different from it.Heptanol elicited moderate activity (EAG/EAG,= 0.52, SD + 0.15) which did not differ significantly from those of propanol, pentanol and hexanol. Other alcohols at the higher end of this series viz.octanol and nonanol had lesser EAG potencies (EAG/EAG,, = 0.35, SD + 0.13 and 0.25, SD + 0.09 respectively) which were not significantly different from that of the control (EAG/EAG,,,= 0.16, SD f 0.06).The lowest EAG response of EAG/EAG,,= 0.19 (SD 2 0.05) was shown by decanol and this response was also close to that of the control.