Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/12/2007
Publication Date: 2/1/2007
Citation: Bundy, C.S., Funk, P.A., Lowry, S., Steiner, R.L. 2007. Thermal cotton defoliation: impact on late-season whiteflies. In: Proceedings of the Beltwide Cotton Conferences, January 9-12, 2007, New Orleans, Louisiana. 2007 CDROM p. 260-262. Interpretive Summary: Silverleaf whitefly is the insect responsible for much of the stickiness that in past years has caused significant economic losses to cotton producers. Thermal defoliation has been shown to eliminate silverleaf whitefly in the field. This research attempts to understand how it works. Initial laboratory results show silverleaf whitefly can survive twelve seconds over 300°F. Therefore the mechanism of control of silverleaf whitefly during thermal defoliation is likely loss of habitat and food supply more than treatment heat. Insects escaping a defoliators hot air are still doomed.
Technical Abstract: The potential upper thermal limits of the silverleaf whitefly were evaluated in the laboratory. Leaves infested with whitefly nymphs and pupae were collected from the field and exposed to a series of increasing temperatures in a drying oven. Heat treatments began at ~158°F (~70°C) and increased at ~10-15 degree intervals until 100% mortality was observed. Controls consisted of 4 additional leaves per run not exposed to the thermal treatment. Both treated and control leaves were then placed individually in petri dishes lined with filter paper and maintained in an incubator at 25°C under a photoperiod of 14:10 LD for ~1 week. Emergence of silverleaf whitefly adults from pupae/nymphs exposed to increasing thermal levels remained relatively similar until temperatures of over 300°F were reached. Temperature did not appear to impact adult emergence until treatments of 331°F (166°C) or greater were reached. Control emergence remained relatively constant, averaging ~70.9%. This research establishes baseline data for the upper thermal limits of silverleaf whitefly survival. Implications for thermal defoliation are briefly discussed.