Putative Vectors of Sugarcane White Leaf Disease in Uda Walawe, Sri Lanka

Sugarcane White Leaf Disease (WLD) is one of the major threats to the sugarcane industry in Sri Lanka. Deltocephalus menoni (Hemiptera: Cicadellidae, Deltocephalinae) is the only locally-identified vector of this phytoplasma disease. Understanding the vector and reservoir of the phytoplasma is essential for effective control of the disease. An experiment was conducted in the entomology laboratory and the Research farm of the Sugarcane Research Institute (SRI), Uda Walawe, Sri Lanka to identify the putative vectors of WLD of sugarcane. Insects available in the sugarcane ecosystem were identified by collecting them using a sweep net and pooter randomly from sugarcane fields, preserving samples and observing morphology. Among the collected insects, leaf hopper sp., Yamatotettix sp., Chlorita paolii, Cicadella viridis, Euscelis sp., Indiocerus lituratus, Kolla ceylonica and Tropidocephala signata were selected for the study as they belong to the family Cicadalidae, which belongs to 75% of phloem-feeding phytoplasma vectors. Deltocephalus menoni was considered as the reference sp. during the study. Honey dew test and erythrosine dye test were conducted to determine the feeding ability of selected insects on sugarcane. pH test and leaf cross-section study were conducted to study the feeding location of the insects on sugarcane leaves. Among test insects, only Yamatotettix sp. was identified as a phloem feeder exhibiting its potential to act as a vector of the sugarcane WLD. Further confirmation of the ability of Yamatotettix sp. to transmit the sugarcane WLD phytoplasma is crucial by conducting disease transmission tests in future.