Short chain alcohols, known attractants for the coconut pest, Rhynchophorus ferrugineus F.(Coleoptera: Curculionidae), were used to improve a 4-methyl-5-nonanol (ferrugineol) baited trap for the weevil. In a Y shaped olfactometer-choice test, 68% weevils selected the ferrugineol baited arm. n-Propanol and n-pentanol elicited responses in 80% and 79% respectively of weevils. Combinations of n-pentanol: ferrugineol (1:l) and n-propanol: ferrugineol (1:l) did not show increased activity (80% and 82% selection respectively). In a field assay, n-propanol and n-pentanol baited traps caught no weevils whereas ferrugineol caught a mean number of 0.42 weevils1 trap/ day. A 1:l combination of ferrugineol with five alcohols viz. n-propanol, n-butanol, n-pentanol, n-hexanol and n-nonanol were field tested as.baits for possible enhancement of activity of ferrugineol. A significantly higher catch of 0.85 weevils/ day/ trap, (p u 0.05, Scheffe's test) was obtained with ferrugineol:n-pentanol. Ferrugineol:hexanol baited traps caught 0.45 weevils/trap/day which was only marginally higher than that of the starjdard, ferrugineol. Other combinations caught fewer weevils (range 0.05-0.2 weevils/trap/day) and the control trap caught no weevils.

Steam bark distillates of the typica and aurancica varieties of Cocos nucifera (host plant) Ternlinulia catappa (Kottamba) and Albizzia urnara Boiv. (Albizzia) (nonhost plants) and Areca catechu L. (Puwak) and Areca concmna Thw. Enum. (Lentheti) (alternate hosts) were subjected to electrophysiological and behavioural assays to compare the attractiveness to the coconut pest, Rhynchophorus ferrugineus F. (Coleoptera: Curculionidae). In the electroantennogram (EAG) assay, the steam distillates of C. nucifera form aurancica elicited the highest response of 79.1% (relative to standard) and the form typica (young bark) 55.6% to the antenna ofR. ferrugineus both values being significantly different (p<0.05, ANOVA, Scheffe's test) from those of the nonhosts T. catappa and A. amara (10.9% and 5.9% respectively). EAGs of old bark (51.4%) steam distillate of C. nucifera form typica did not differ significantly from that of the young bark distillates (55.6%). The two alternate hosts, A. catechu and A. concinna showed moderate EAG activities (29.4% and 25.9% respectively) between those of host varieties and nonhosts. In a behavioural assay (choice test) using an olfactometer the steam distillates of host palms were more attractive (pc0.05, ANOVA, Scheffe's test) to the red weevil than those of the nonhosts. C. nucifera form aurancica was more , attractive (79.9% attraction to the baited arm) than typica. Between young and old palms of C. nucifera form typica, no significant difference (p>O.OB, ANOVA, Scheffe's test) in the behavioural activity was observed. The alternate hosts showed moderate activity.

: 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.

Electroantennogram (EAG) responses of male and female Rhynchophom fernginem P. (Coleoptera: Curculionidae) to sixteen terpenes were determined. The chemoreceptive sensitivity of I?. femcgineus was sensitive to the size and the position of the oxygen function, degree of unsaturation and the arrangement of olefinic bonds in the molecules. A significant (P < O.UOl, t-test) reduction of the EAGs of terpene alcohols was observed when hydro@ groups were acetylated. Thus linalool and terpineol (EAGs 1750 and 1752 resqectively) elicited EAGs of 11.24 and 12.36 respectively with the corresponding acetates. The antenna] responsiveness of R. femginew to terpene alcohols did not differ significantly from their corresponding mrbonyl analogues. Terpenes bearing non-terminal OWC = 0 had higher EAG potency significantly different (P. : 0.001) from those with terminal-OW C=O. Combining the above findings with the olefinic moieties of the molecule, the terpenes could be divided into two class'es viz. a) Terpenes with 3 unsaturations, 1-3 unsaturation with non terminal-OH /C= 0 and cyclic structure with non-terminal-OH/C=O b) Terpenes having isolated diene systems, terpenes with terminal OH/C=O and terpenes having both of the above characters. Comparison of EAG activities of the two classes indicated that the former category had greater EAG potency (class mean 18.6) significantly different (P < 0.001, t-test) from the latter (class mean 14.9). However even the most favoured structure elicited l w e r EAG response than the natural host attractant, isolated from the steamvolatiles of coconut bark, (EAG 31.49).