Comparative electroantennogram study of Parallelia algira (Lepidoptera: Noctuidae) and Conogethes punctiferalis (Lepidoptera: Pyralidae) to general plant volatiles

Abstract

Male and females of Conogethes punctiferalis and Parallelia algira were evaluated for their olfactory sensitivity towards general plant volatiles by e1ectroantennogram recording technique (EAG). A high degree of response uniformity between the species as well as the sexes was observed with most of the volatiles except for terpenoids. In both the pest species, the effectiveness of saturated aliphatic alcohols (1-9) was maximal at a chain length of six carbon atoms. The EAG response of male and female P. algira to six carbon alcohol (hexanol) was found to 2.8 ± 0.05 and 2.75 ± 0.03 milli volts (mv), respectively. Likewise, the EAG responses of C. punctiferalis male and female to hexanol were obtained as 2.75 ± 0.04 and 2.63 ± 0.02 mv, respectively. EAG's elicited by aldehydes were greater than the corresponding alcohols in both the insects. Some selective sensitivity of the olfactory receptors was observed for the perception of terpenoids in males of P. algira. Citral evoked the highest EAG response in males of P. algira which was 103.32 ± 4.92% in comparison to females which was 58.27 ± 7.4%. As both C. punctiferalis and P. algira shared the same host plant for feeding and oviposition, their EAG spectra were also similar except for terpenoids. Absolute EAG responses of all the volatiles tested were found to be comparatively lower in C. punctiferalis than in P. algira. Thus, the antennal olfactory receptors of both the insect pests were sensitive to the functional group classification of the compound and the particular chain length and/or molecular configuration of the compound.