Field evaluation of synthetic kairomonal attractants against major lepidopteran pests of castor.

Abstract

The tobacco caterpillar (Spodoptera litura F.), semilooper (Achaea janata L.) and capsule borer (Conogethes punctiferalis Guenee) are the most destructive lepidopteran insect pests of castor. Developing new environmentally benign alternative monitoring and management system for these pests may reduce the frequency of application of insecticides and impact on the environment. Therefore, the objective of the present study was to evaluate the attractiveness of synthetic kairomones against these lepidopteran pests under laboratory and field conditions. Methodology: Antennal responses of lepidopteran species to six synthetic kairomones (benzaldehyde, benzyl acetate, p-anisaldehyde, phenyl acetaldehyde, 2-phenyl ethanol and methyl salicylate) were studied by electroantennogram (EAG). Lures of three synthetic kairomones elicited strong EAG responses viz., phenyl acetaldehyde, benzaldehyde and 2-phenyl ethanol were prepared in single and combinations and field tested using three trap designs (funnel trap, sleeve trap and water trap) for trapping of lepidopteran pests in castor. Results: Phenyl acetaldehyde elicited strongest EAG responses for female and male moths of S. litura (-1.518 to -2.221 mV and -1.756 to -2.214 mV, respectively). Female and male moths of A. janata showed significantly greater EAG responses to benzaldehyde (-2.573 to -3.336 mV and -2.377 to -3.396 mV, respectively). The highest EAG responses of female and male moths of C. punctiferalis were elicited by 2-phenylethanol (-2.563 to -3.152 mV and -2.475 to -2.903 mV, respectively). In field experiment, water trap baited with phenyl acetaldehyde+2-phenyl ethanol recorded significantly higher moth catches of S. litura (6.8 moths/trap/wk) and C. punctiferalis (5.8 moths/trap/wk). Interpretation: Combination of phenyl acetaldehyde and 2-phenyl ethanol in water trap can be used for monitoring of the lepidopteran pests in castor. The synthetic attractants has potential in developing management methods such as mass trapping or 'attract and kill system' for the lepidopteran pests of castor.