Relative susceptibility of promising lines of Gudmar (Gymnema sylvestre R. Br.) against Oleander aphid, Aphis nerii Fonscolombe

Résumé fourni par la source

Gudmar, Gymnema sylvestre R. Br. (Family: Apocynaceae), is an important medicinal crop valued for its diverse therapeutic properties, particularly its anti-diabetic potential. The oleander aphid, Aphis nerii Fonscolombe (Hemiptera: Aphididae), is an important sucking pest causing considerable damage to Gudmar, especially in winter. Thus, the present investigation was undertaken to assess the relative susceptibility of five promising lines of Gudmar to A. nerii under field conditions during Rabi, 2024-25 and Rabi, 2025-26. The pooled mean aphid index of the promising lines ranged from 1.33 to 2.64 per plant. Among the evaluated lines, TNAU-Local recorded the lowest aphid index (1.33) and was categorized as highly resistant, while TNGSy-28 (1.91) was categorized as resistant. TNGSy-14 (2.31) and TNGSy-20 (2.18) were categorized as susceptible, whereas TNGSy-16 recorded the highest aphid index (2.64) and was categorized as highly susceptible. The considerable variation in susceptibility observed among the promising lines indicates the presence of differential host plant response to A. nerii. The relatively less susceptible lines, particularly TNAU-Local and TNGSy-28, may serve as valuable genetic resources for future screening and breeding programmes aimed at developing aphid-resistant Gudmar cultivars. The identified resistant lines may also contribute to reducing dependence on insecticides and can be effectively integrated with other components of integrated pest management for sustainable management of A. nerii in Gudmar.