Effectiveness of the Usher Plant Extracts from High Altitude as a Safe Control Method Against Pomegranate Aphid, Aphis punicae, on Pomegranate Trees

The pomegranate (Punica granatum L.) (Lythraceae) is commonly infested with many insect pests, especially aphids. The pomegranate aphid, Aphis punicae (Hemiptera: Aphididae) is the important insect pest on pomegranate trees where it infests leaves, buds and fruits. It causes damage that reduces the yield of pomegranate fruits. This investigation estimated the control efficacy of leaf and fruit extracts of the usher plant, Calotropis procera (Apocynaceae) on A. punicae. The phenols and flavonoids in both extracts were determined by HPLC analysis. Total phenols and flavonoids were 23.089 and 2.223 mg/g in leaves and fruits, respectively. We found that LC50 and LC90 values of leaf extract (251.3 and 1017.9 µg/mL, respectively) were significantly lower than those of fruit extract (622.5 and 2521.8 µg/mL, respectively). Field experiments using leaf extract resulted in an LC50 within one- and two-week intervals. Results of field application showed there was always significantly greater aphid reductions in the treatment where the spray was two weeks old over treatment that was one week old. However, there were no differences always noticed for spraying that was a week old in both treatments. This result stated that the application of C. procera leaf extract at one-week intervals is efficient to control pomegranate aphids with more than 90% of a reduction rate. Further experiments could be done to estimate the safety of this plant extract on beneficial organisms such as insect predators and parasitoids associated with the insect pests.