Aphicidal activity of five plant extracts applied singly or in combination with entomopathogenic bacteria, Xenorhabdus budapestensis against rose aphid, Macrosiphum rosae (Hemiptera: Aphididae)

Abstract

The rose aphid Macrosiphum rosae (L.) is now a globally spread insect species damages rose plants affecting quality and productivity. Botanical insecticides are excellent alternative to synthetic pesticides, as they have minimal environmental persistence and toxicity, and are more compatible with the biocontrol agents than synthetic pesticides. This study aimed to evaluate extracts of five plant species i.e. Citrullus colocynthis, Tagetes erecta, Rosmarinus officinalis, Thymus vulgaris, and Withania somnifera; and entomopathogenic bacteria (EPB), Xenorhabdus budapestensis against M. rosae, as individual and concomitant treatments to determine their compatibility under laboratory conditions. Results indicated that the five plants extracts and EPB applied individually had immense contact or residual toxicity against M. rosae. Methanol extract of T. erecta significantly proved to be more effective as aphicide than ethanol and acetone extracts of five tested plants. Similarly, the results also show a direct, significant relationship between the mortality rates and both EPB cell suspension concentration and exposure time when applied individually. Moreover, three days after treatment, the combination of EPB and each plant extract resulted in a significantly higher M. rosae mortality than the EPB or plant extract alone. We conclude that five plants extracts especially T. erecta had compatible capacity with EPB, thus it could be used in integrated aphid management programs.