Identifying Leafhopper Targets for Controlling Aster Yellows in Carrots and Celery.

Zsofia Szendrei,Patrick T Stillson

doi:10.3390/insects11070411

Abstract

Aster yellows phytoplasma (Candidatus Phytoplasma asteris) is a multi-host plant pathogen and is transmitted by at least 24 leafhopper species. Pathogen management is complex and requires a thorough understanding of vector dynamics. In the American Midwest, aster yellows is of great concern for vegetable farmers who focus on controlling one vector, Macrosteles quadrilineatus—the aster leafhopper. However, vegetable-associated leafhopper communities can be diverse. To investigate whether additional species are important aster yellows vectors, we surveyed leafhopper communities at commercial celery and carrot farms in Michigan from 2018 to 2019 and conducted real-time PCR to determine infection status. Leafhoppers were collected within crop fields and field edges and identified with DNA barcoding. Overall, we collected 5049 leafhoppers, with the most abundant species being M. quadrilineatus (57%) and Empoasca fabae—the potato leafhopper (23%). Our results revealed the most abundant aster yellows vector in Michigan in both crops is M. quadrilineatus, but we also found that E. fabae may be a potential vector for this pathogen. While several taxa reside in and near these crops, we did not find strong evidence that they contribute to phytoplasma infection. These findings indicate that M. quadrilineatus should be the primary target for controlling this pathogen.

Highlights

Aster yellows phytoplasma (Candidatus Phytoplasma asteris) is an insect-vectored plant pathogen [1] which causes a variety of symptoms including yellowing, virescence, phyllody, witch’s broom, and premature death [2]
Our results revealed the most abundant aster yellows vector in Michigan in both crops is M. quadrilineatus, but we found that E. fabae may be a potential vector for this pathogen
Our leafhopper survey confirmed that M. quadrilineatus is the primary leafhopper vector of aster yellows phytoplasma in Michigan celery and carrot agroecosystems, which is consistent with findings from Ohio [12] and Wisconsin [78] carrot fields, and is the first study to confirm this in Midwestern celery fields

Summary

Introduction

Aster yellows phytoplasma (Candidatus Phytoplasma asteris) is an insect-vectored plant pathogen [1] which causes a variety of symptoms including yellowing, virescence, phyllody, witch’s broom, and premature death [2]. Aster yellows has been reported to reduce yields by 10% [4] and is one of the most widespread phytoplasmas, affecting 14 vegetable crops across various plant families [5,6,7]. It is vectored by at least 24 leafhoppers [8], which must acquire the phytoplasma from the environment by feeding on infected plants [1], since phytoplasmas are rarely transovarial [1,9]. Polyphagous leafhoppers can acquire phytoplasma from crops or weedy host plants and spread it among susceptible crop fields or between the field and field edge [7]

Methods

Results

Discussion

Conclusion