Submitted to: Silverleaf Whitefly Research, Action and Technology Transfer Plan
Publication Type: Proceedings
Publication Acceptance Date: January 25, 2002
Publication Date: December 10, 2002
Citation: Mckenzie, C.L., Puterka, G.J. 2002. Efficacy of sucrose octanoate to whitefly using a plant-based bioassay. Silverleaf Whitefly Research, Action and Technology Transfer Plan. Technical Abstract: The objectives of this study were to determine the insecticidal activity of a synthetic analogue of natural sugar esters (sucrose octanoate (SO)) found in leaf trichomes of wild tobacco to egg, nymph and adult sweetpotato whitefly (WF), Bemisia tabaci biotype B, (=silverleaf WF, Bemisia argentifolii), vector of Begomoviruses. A plant-based petri dish bioassay system was developed to hold single tomato leaves infested with WF for their entire life cycle (egg to adult). The SO solutions were applied using an ultra-low volume spray device that consisted of a spray platform that holds a pressurizable spray bottle at the proper distance and angle. Both the abaxial and adaxial sides of the leaf were sprayed with 200 ul of SO solution. SO rates applied to eggs, nymphs or adult WF varied depending on the life stage evaluated. Freshly laid WF eggs (24-48 hrs old) were sprayed and evaluated 7, 14, 21 and 28 DAT (until adult emergence). WF nymphs were sprayed at the crawler/2nd instar stage & evaluated at 1, 3, 7 & 14 DAT (until adult emergence). WF adults were sprayed and evaluated 1, 3 & 7 DAT. Each concentration was replicated 5 times. WF eggs & nympph mortality increased over time whereas WF adult mortality virtually remained the same. Freshly laid eggs sprayed with the higher concentrations (12,000 to 48,000) had significantly fewer adults emerge. Lower rates applied to freshly laid eggs had little effect on adult emergence. Toxicity of SO to WF nymphs ranged from LC90 values of 55,827 ppm to 2,225 ppm at 1 & 14 DAT (=adults emerged), respectively.Adult WF were killed immediately if they were going to die; LC90 values calculated 1 DAT were 5,174 ppm. Preliminary results indicate SO could be an effective tool for nymph&adult WF control to levels of more than 90% at higher rates of SO. Good coverage is key to efficacy.