Insights in the Role of Leaf Surface Wax Chemicals of Luffa acutangula (Cucurbitaceae) in the Attraction and Oviposition of Aulacophora lewisii.

Abstract

Adults of Aulacophora lewisii Baly (Coleoptera: Chrysomelidae) defoliate Luffa acutangula (L.) Roxb. plants, and lessen its production. Successful oviposition by herbivorous insects on their host is an important factor in the host acceptance process. In this context, it is important to investigate whether leaf surface wax chemicals from three ridge gourd cultivars (Abhiskar, Debsundari and Jaipur Long) could serve as short-range attractants and stimulate oviposition in A. lewisii females. Surface waxes were isolated from each leaf using the gum arabic method. Twenty-one n-alkanes from n-C₁₂ to n-C₃₄ and nine free fatty acids (FFAs) from C12:0 to C19:0 were detected and quantified by GC-MS and GC-FID, respectively. One leaf equivalent surface wax (LESW) of each cultivar or a synthetic blend consisting of n-alkanes and FFAs mimicking one LESW of the same cultivar served as attractants through Y-tube olfactometer bioassays and stimulated oviposition in A. lewisii females. However, one LESW of Jaipur Long or a synthetic blend of n-alkanes and FFAs mimicking one LESW of Jaipur Long served as more potent oviposition stimuli in females than one LESW or synthetic blends mimicking one LESW of the other two cultivars. In field trials, a synthetic blend of pentadecane, heptadecane, pentacosane, hexacosane and linoleic acid mimicking Jaipur Long at mole ratios of 1:14.45:1.68:1.38:1.62 at 1.6 g/ml petroleum ether when used as lure in funnel traps resulted in attraction of A. lewisii. Hence, the above synthetic blend could be used as a lure in baited traps in eco-friendly pest management strategies.