Influence of Adaxial and Abaxial Leaf Surface Wax Alkanes and Free Fatty Acids of Lagenaria siceraria on Short‐Range Attraction and Oviposition‐Site Selection in Helicoverpa armigera

Larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) can cause complete defoliation of Lagenaria siceraria (Molina) Standl., commonly known as bottle gourd, resulting in substantial yield losses in India. Female moths oviposit exclusively on the abaxial leaf surface, rather than the adaxial leaf surface, suggesting that abaxial leaf surface wax (ABLSW) chemicals serve as a short‐range attractant and cues for oviposition‐site selection. This study investigates the role of ABLSW chemicals, specifically alkanes and free fatty acids (FFAs), from three bottle gourd cultivars—ANKUR AMIT (AMIT), KSP‐1720 (KSP) and ANKUR GOLU (GOLU)—as short‐range attractants and cues for oviposition‐site selection by H. armigera females. Twenty n ‐alkanes ( n ‐C 14 to n ‐C 36 ) were identified in both adaxial and abaxial leaf surface waxes of these three cultivars. In the adaxial leaf surface waxes (ADLSW), 14 and 13 FFAs within the range of C12:0 to C22:0 were detected in AMIT and KSP, and GOLU, respectively. In contrast, in the ABLSW, 13 and 14 FFAs were detected in AMIT and GOLU, and KSP, respectively. In the ABLSW chemicals, heptadecane and palmitoleic acid were the predominant n ‐alkane and FFA, respectively, in these cultivars. Females exhibited attraction and oviposition on 0.25 leaf equivalent of crude ABLSW from these cultivars compared to solvent controls (petroleum ether), as demonstrated by Y‐tube olfactometer and oviposition assays. Synthetic blends replicating the composition of 0.25 leaf equivalent of crude ABLSW—comprising heptadecane, pentacosane, heptacosane, palmitoleic acid and stearic acid for AMIT; hexadecane, heptadecane and palmitoleic acid for KSP; and heptadecane, palmitoleic acid and stearic acid for GOLU—functioned as candidate active compounds for short‐range attraction and cues for oviposition‐site selection in H. armigera . Females displayed comparable egg‐laying responses to all three synthetic blends when tested against each other. Therefore, these blends may serve as effective lures for baited traps in pest management strategies.