Screening potential insect vectors in a museum biorepository reveals undiscovered diversity of plant pathogens in natural areas

Abstract

Phytoplasmas ( Mollicutes, Acholeplasmataceae), vector‐borne obligate bacterial plant parasites, infect nearly 1,000 plant species and unknown numbers of insects, mainly leafhoppers (Hemiptera, Deltocephalinae), which play a key role in transmission and epidemiology. Although the plant–phytoplasma–insect association has been evolving for >300 million years, nearly all known phytoplasmas have been discovered as a result of the damage inflicted by phytoplasma diseases on crops. Few efforts have been made to study phytoplasmas occurring in noneconomically important plants in natural habitats. In this study, a subsample of leafhopper specimens preserved in a large museum biorepository was analyzed to unveil potential new associations. PCR screening for phytoplasmas performed on 227 phloem‐feeding leafhoppers collected worldwide from natural habitats revealed the presence of 6 different previously unknown phytoplasma strains. This indicates that museum collections of herbivorous insects represent a rich and largely untapped resource for discovery of new plant pathogens, that natural areas worldwide harbor a diverse but largely undiscovered diversity of phytoplasmas and potential insect vectors, and that independent epidemiological cycles occur in such habitats, posing a potential threat of disease spillover into agricultural systems. Larger‐scale future investigations will contribute to a better understanding of phytoplasma genetic diversity, insect host range, and insect‐borne phytoplasma transmission and provide an early warning for the emergence of new phytoplasma diseases across global agroecosystems.

Abstract

Phytoplasmas are a diverse group of obligate intracellular bacterial parasites, and diseases associated with these bacteria are among the most important problems affecting agriculture worldwide. However, most knowledge of the diversity and ecology of phytoplasmas and their hosts has been accumulated through studies of phytoplasma disease epidemiology in agroecosystems. In light of recent attention to the importance of wildlife as reservoirs of emergent diseases, we screened potential insect vectors collected in natural areas and preserved in museum biorepositories, 6 of them were positive for the presence of phytoplasmas.