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Preliminary laboratory studies have shown the presence of pheromones ofLeucinodes orbonalis , the brinjal shoot and pod borer found in Sri Lapka. Bioassay using an olfactometer revealed that the virgin female of L. orbonalis produces a sex pheromone which elicit highest response during the f i s t night. It was also shown that the pheromone production was discontinuous, the maximum production being around 22 : 00-24 :00 hours. Chemical investigations of the pheromone gland contents of calling females showed the presence of (E)-11-hexadecenyl acetate as the major compound while tracer amounts of (E)-11-hexadecen-1-01 was also present. Activity of the synthetic (E)-11-HDA was shown to be equal to that of the natural sample by laboratory bio assay although in field trials the synthetic sample attracted lesser number of males.

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.

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