Page 1 of 41 Razi, Phytopathology 1 1 2 Detection of Citrus Huanglongbing Associated ‘ Candidatus Liberibacter asiaticus’ 3 in Citrus and Diaphorina citri 4 in Pakistan, Seasonal Variability and Implications on Disease Management 5 6 Muhammad F. Razi, Manjunath L. Keremane, Chandrika Ramadugu, Mikeal Roose, 7 Iqrar A. Khan, and Richard F. Lee 8 First and fifth authors: University of Agriculture, Faisalabad, Pakistan; second and sixth authors: 9 U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), National Clonal 10 Germplasm Repository for Citrus and Dates, Riverside, CA 92507; third and fourth authors: 11 Department of Botany and Plant Sciences, University of California, Riverside, CA 92507 12 Corresponding author: Richard Lee; E-mail address:
[email protected] 13 14 ABSTRACT 15 We report the detection of the HLB associated bacterium, ‘ Candidatus Liberibacter asiaticus’ 16 (Las) from both plants and insects in Pakistan and the seasonal variability in the numbers of Las 17 positive psyllid vector, Diaphorina citri . Our studies showed that Las was detectable from trees 18 in areas with maximum temperatures reaching nearly 50°C (average maximum 42°C). However, 19 the bacterium was present at very low levels in psyllids both in summer (June-August) and 20 autumn (September-November) in contrast to reports from Florida, USA, where the bacterium 21 was detectable at very high levels during October-November. We hypothesize that hot summer 22 temperatures in Pakistan may interfere with acquisition and replication of Las in psyllids and Phytopathology "First Look" paper • http://dx.doi.org/10.1094/PHYTO-08-13-0224-R posted 10/17/2013 23 may lead to dead and/or non-transmissible Las in plants.