COS 282-6 - Detection of Phytoplasma in Wild Grasses and Hemipteran Insects of Texas

Abstract: Hemipterans are potential vectors of bacterial phytoplasma disease transferred to crop plants and a variety of wild plants worldwide. There are several strains of phytoplasma which present differing symptoms including yellowing or whitening of leaves and leaf proliferation. These symptoms hinder a plant’s ability to uptake nutrients and can lead to mortality. Other plants may carry phytoplasma and be asymptomatic, leaving no symptoms of disease. Previous research has documented disease presence in crop plants of Texas, but wildlife grasses remain untested for disease. As native wildlife has been displaced by invasive grass species, understanding interaction between hemipterans and grass is important. This research will investigate whether phytoplasma is present in grass and insects. The goal of this study is to identify hemipteran species associated with grass and insects and test for the presence of phytoplasma in grass and insects. To address the goals of this study, collection sites were established in the Hill Country and Blackland Prairie of Bexar County, Tx. Native and invasive wild grass species were sampled as well as their associated hemipteran insects in the summer, fall, and winter of 2022. For phytoplasma detection, DNA was extracted from sampled material and real time PCR was subsequently performed to test for phytoplasma presence. For species identification of insects, DNA barcoding was performed after PCR with COI primers. Here we show three hemipteran species identified from the summer and fall are known from previous research to carry phytoplasma elsewhere. The number of total species will be available after identification is completed. Of the summer insects, none have exhibited presence of phytoplasma. Hemipterans from the fall and winter will soon be tested. Of three native grass species tested from winter, the genetic signature of a potentially emerging pathogen was found in one species of grass. The study suggests the presence of noteworthy bacterial pathogens in native wild grasses, a novel finding in wild grasses of Texas. These findings additionally suggest invasive grasses may serve as a reservoir of bacterial pathogens, as an invasive leafhopper is highly associated with the grass and known to carry phytoplasma in other regions of the world. Monitoring disease presence will become an important practice to appropriately respond to or evade ecological crisis.