Samah E. M. Nosier *(1), Hagar M. M. Salem (1), and Ashraf Salah (1)
(1). Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt.
(*Corresponding author: dr.ashrafsalah@yahoo.com ).
Received: 01/06/2026 Accepted: 29/07/2026
Abstract
The rose aphid, Macrosiphum rosae L. (Hemiptera: Aphididae), is one of the most destructive insect pests affecting rose production by reducing both flower quality and market value. This study investigated the relationship between rose flower cell sap pH and infestation by M. rosae under plastic greenhouse conditions. Three rose cultivars (Dream, Freedom, and Montana) differing in flower cell sap pH were evaluated at two greenhouse locations in Cairo (El-Zohrya Garden) and Alexandria (International Garden), Egypt, during the 2025/2026 growing season. Aphid populations were monitored throughout the flowering period, and flower sap pH was determined using a digital pH meter. In addition, selected biochemical constituents of aphids feeding on each cultivar, including total carbohydrates, total lipids, total proteins, and several enzyme activities (lipase, kinase, chitinase, phosphatase, α-esterase, and β-esterase), were determined under laboratory conditions.
The results showed significant differences in aphid infestation among the three rose cultivars. Dream, which exhibited the lowest flower sap pH (4.5), had the lowest aphid population density, whereas Montana, with the highest pH (6.5), showed the greatest infestation. Freedom (pH 5.3) displayed intermediate values. Similar trends were observed at both experimental locations. Aphids feeding on Dream also exhibited lower concentrations of total carbohydrates, proteins, lipids, and enzyme activities compared with those feeding on Freedom and Montana.
These findings indicate a significant association between flower sap pH, rose cultivar, and aphid infestation under greenhouse conditions. The results suggest that flower sap acidity may contribute to differences in cultivar susceptibility to M. rosae. However, because other varietal biochemical characteristics were not investigated, the observed relationship should be interpreted with caution.
Key words: Macrosiphum rosae; Rosa gallica; flower cell sap pH; aphid infestation; greenhouse conditions; host plant resistance.
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How to cite this article – APA Style
Nosier, S. E. M., Salem, H. M. M., & Salah, A. (2026). Influence of rose flower cell sap pH on infestation by the rose aphid (Macrosiphum rosae L.) under plastic greenhouse conditions. Research Journal of Science (RJS), 4(1), 43–51.