Detecting phytoplasma strains of Lethal Yellowing (LY) and Texas Phoenix Palm Decline (TPPD) in South Texas

Phytoplasma bacterium affects numerous plants and crops, causing approximately 600 diseases in several hundred plant species.  The primary focus of this research is the phytoplasma strain Texas Phoenix Palm Decline (TPPD).  This strain of phytoplasma produces symptoms which include: premature drop of fruit, inflorescence, necrosis and root decay.   Phytoplasma transmission spreads from plant to plant by insect vectors.  After feeding on an infected plant, the bacterium traverse the intestinal tract wall, multiply in the hemolymph and pass through salivary glands and multiply.  The insect then introduces the bacterium along with salivary fluids into the phloem of a new host plant.  Phytoplasma bacterium lacks a cell wall, making them impossible to culture in media.  The specific insects that we are studying are potential vectors for both strains of phytoplasma, Haplaxius crudus (Homoptera: Cixiidae). These insects are plant phloem feeders, and H. crudus is a plant hopper that is typically found on coconut palms in Florida and the Caribbean.  Our study examined insects collected from areas of South Texas. We tested the hypothesis that Myndus crudus which is the confirmed vector for lethal yellowing (LY) could also be the vector insect capable of transmitting TPPD.  Forty two insects were collected and placed in collection tubes.  Insect DNA was extracted using a modified CTAB protocol and then tested using a nested primer set.   Preliminary data show a positive detection rate of 0.024%.