The oleander aphid, Aphis nerii, is a polyphagous pest of ornamental and medicinal plants, impairing plant vigor and compromising medicinal value through toxin and honeydew secretion. Gymnema sylvestre (Retz.) R. Br. ex Sm a key medicinal plant for diabetes treatment, is particularly vulnerable. Evaluating aphid fitness on these hosts supports pest forecasting and ecofriendly management. This study mainly focused on comparative biology and demographic parameters of A. nerii on G. sylvestre and Leptadenia reticulata to identify vulnerable developmental stages and inform effective pest management strategies. A. nerii, along with its natural enemies Cheilomenes sexmaculata and a Hemerobius sp, were documented by using both morphological keys as well as molecular level (GenBank accession numbers: PQ432429.1, PQ553453.1, and PQ524096.1, respectively). Phylogenetic analysis of C. sexmaculata revealed a close relationship with sequences KP851143.1 and LC557471.1, originally reported from Punjab, India, and Kyoto, Japan. A. nerii exhibited five distinct nymphal instars before reaching adulthood. The overall nymphal developmental period was significantly prolonged on L. reticulata (11.40 ± 1.34 days) compared to G. sylvestre (t = -5.125, p < 0.01). Both pre-oviposition (1.52 ± 0.52 days, t = -2.846, p < 0.01) and post-oviposition periods (2.15 ± 0.76 days, t = -2.407, p < 0.03) were notably longer on L. reticulata. Fecundity was significantly higher in aphids reared on G. sylvestre (41.20 ± 6.30 nymphs/female) than on L. reticulata (35.37 ± 6.87 nymphs/female; t = 3.142, p < 0.01). The r value was greater on G. sylvestre (r = 0.24) than on L. reticulata (r = 0.20), indicating that A. nerii population is growing faster on the former host. G. sylvestre (RO=41.76 ± 0.136 nymphs) than L. reticulata (RO=36.36 ± 0.121 nymphs; t = 29.59, p < 0.01). G. sylvestre had a quicker population doubling time (2.87 days) than L. reticulata (3.46 days), and its overall survival rate was greater (79.71%) than L. reticulata (69.77%). These results showed G. sylvestre serves as a more suitable and favorable host for A. nerii compared to L. reticulata. Understanding these demographic traits is essential for predicting population dynamics, targeting vulnerable developmental stages, and formulating effective strategies for A. nerii in medicinal crop ecosystem.

Comparative fitness of oleander aphid, Aphis nerii Boyer de fonscolombe (Hemiptera: Aphididae) on selected medicinal hosts using an age-stage, two-sex life table

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2025年10月29日

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K. T. Shivakumara,
M. C. Keerthi,
A. C. Polaiah,
S. S. Udikeri,
C. Divya,
K. Swapnarani

摘要

The oleander aphid, Aphis nerii, is a polyphagous pest of ornamental and medicinal plants, impairing plant vigor and compromising medicinal value through toxin and honeydew secretion. Gymnema sylvestre (Retz.) R. Br. ex Sm a key medicinal plant for diabetes treatment, is particularly vulnerable. Evaluating aphid fitness on these hosts supports pest forecasting and ecofriendly management. This study mainly focused on comparative biology and demographic parameters of A. nerii on G. sylvestre and Leptadenia reticulata to identify vulnerable developmental stages and inform effective pest management strategies. A. nerii, along with its natural enemies Cheilomenes sexmaculata and a Hemerobius sp, were documented by using both morphological keys as well as molecular level (GenBank accession numbers: PQ432429.1, PQ553453.1, and PQ524096.1, respectively). Phylogenetic analysis of C. sexmaculata revealed a close relationship with sequences KP851143.1 and LC557471.1, originally reported from Punjab, India, and Kyoto, Japan. A. nerii exhibited five distinct nymphal instars before reaching adulthood. The overall nymphal developmental period was significantly prolonged on L. reticulata (11.40 ± 1.34 days) compared to G. sylvestre (t = -5.125, p < 0.01). Both pre-oviposition (1.52 ± 0.52 days, t = -2.846, p < 0.01) and post-oviposition periods (2.15 ± 0.76 days, t = -2.407, p < 0.03) were notably longer on L. reticulata. Fecundity was significantly higher in aphids reared on G. sylvestre (41.20 ± 6.30 nymphs/female) than on L. reticulata (35.37 ± 6.87 nymphs/female; t = 3.142, p < 0.01). The r value was greater on G. sylvestre (r = 0.24) than on L. reticulata (r = 0.20), indicating that A. nerii population is growing faster on the former host. G. sylvestre (R_O=41.76 ± 0.136 nymphs) than L. reticulata (R_O=36.36 ± 0.121 nymphs; t = 29.59, p < 0.01). G. sylvestre had a quicker population doubling time (2.87 days) than L. reticulata (3.46 days), and its overall survival rate was greater (79.71%) than L. reticulata (69.77%). These results showed G. sylvestre serves as a more suitable and favorable host for A. nerii compared to L. reticulata. Understanding these demographic traits is essential for predicting population dynamics, targeting vulnerable developmental stages, and formulating effective strategies for A. nerii in medicinal crop ecosystem.