Toxicity of newly isolated piperideine alkaloids from the red imported fire ant, Solenopsis invicta Buren, against the green peach aphid, Myzus persicae (Sulzer)

The green peach aphid, Myzus persicae (Sulzer), is a major insect pest of many agronomic and horticultural crops and is distributed worldwide. Aphid management is often based on application of insecticides. However, the aphid is now resistant to many of these and much interest has recently developed in identification of novel alternative insecticides. Venom isolated from the red imported fire ant, Solenopsis invicta Buren, is composed of two groups of alkaloids, piperidines and piperideines, and has shown activity against many organisms including fungi, bacteria, mites and several insects. Prior to the study reported herein, no information on the venom’s activity to Myzus persicae has been reported. Both of the alkaloids were active against M. persicae. The 24 h LC50 values were116.6 and 91.5 ppm for the piperideine and piperidine extracts, respectively. Based on overlap of the 95% fiducial limits the LC50 values for the two alkaloids did not significantly differ. At the high dosages, mortality occurred in as few as four hours and all treated aphids were dead by six hours. Little additional mortality was detected in the 48-h observation. Both piperideine and piperidine extracts isolated from red imported fire ant venom possess sufficient activity to cause death of green peach aphids and at high dosages, death occurs rapidly. In the search for new replacements to synthetic insecticides, these extracts may offer a novel but potentially successful alternative.