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., Hunter, W.B., Lapointe, S.L., Dang, P. 2002. Iridovirus: potential entomopathogenic biocontrol agent for whitefly. Silverleaf Whitefly Research, Action and Technology Transfer Plan. : Fourth Annual Review of hte Second 5-Year Plan and Final Report for 1992-2002. USDA-ARS 2002-01:162. Technical Abstract: A newly described entomopathogenic virus was recently discovered in south Florida whitefly (WF) populations and was determined to be an iridovirus by DNA analysis. Invertebrate iridescent virus 6 (IIV-6) is known to be pathogenic to insects including WF. Demonstrated modes of transmission for iridovirus in other insects have been shown through oral ingestion and cuticular wounding or abrasions. Traditionally, many biological agents are applied by foliar spray application; therefore, we attempted to determine if this would be a feasible method of application of iridovirus to control WF on tomato. 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 iridovirus 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. Uniform infestations of WF were allowed to acclimate on tomato leaves in the petri dish bioassay system. Abaxial and adaxial leaf surfaces were sprayed with 200 ul of virus preparation in a cold room. Controls were sprayed with PBS buffer only. Petri dishes were placed upright in an incubator at 22C under a L/D, 16:8 photoperiod. WF were harvested at 10, 14 and 18 days post spray and were subjected to PCR analysis for presence of IIV6. Although we could demonstrate infection in WF per os, spray applications were inconclusive. When virus solutions were sprayed onto WF and plant tissues no apparent virus infection was detected. This may be due low virus titer in our spray solutions; WF did not ingest surface droplets when feeding, and/or the inability of the virus to remain viable on the leaf surface.