Fly Density Does Not Limit Ceratocystis fimbriata Transmission to Sweetpotato by Drosophila hydei, Revealed Through Molecular Diagnostics

K Avila ¹, M Stahr ^2,3, A Lytle ⁴

¹North Carolina State University at Raleigh, Entomology & Plant Pathology, 4122 Plant Sciences Building - Box 7825, 840 Oval Drive, Raleigh, North Carolina, United States, 27606; kjavila@ncsu.edu.
²Corteva Agriscience Indianapolis, Crop Protection Discovery and Development, 9330 Zionesville Rd, Indianapolis, Indiana, United States, 46268-1053.
³Michigan, United States; madison.stahr@corteva.com.
⁴Western Carolina University, Safety and Risk Management, 1 University Way, Cullowhee, North Carolina, United States, 28723; alafferty@wcu.edu.
⁵North Carolina State University at Raleigh, Entomology and Plant Pathology, 1575 Varsity Drive, Raleigh, Raleigh, North Carolina, United States, 27606; jmmasca2@ncsu.edu.
⁶North Carolina State University at Raleigh, Entomology & Plant Pathology, Raleigh, North Carolina, United States; ashuseth@ncsu.edu.
⁷North Carolina State University at Raleigh, Entomology & Plant Pathology, Raleigh, North Carolina, United States; matt_bertone@ncsu.edu.
⁸North Carolina State University at Raleigh, Department of Entomology and Plant Pathology and NC Plant Sciences Initiative, 4122 Plant Sciences Building, Campus Box 7825, 840 Oval Drive, Raleigh, North Carolina, United States, 27695-7001; lmquesad@ncsu.edu.

⁰North Carolina State University at Raleigh, Entomology & Plant Pathology, 4122 Plant Sciences Building - Box 7825, 840 Oval Drive, Raleigh, North Carolina, United States, 27606; kjavila@ncsu.edu.

Phytopathology +

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October 12, 2025

View abstract on PubMed

Summary

Fruit flies (Drosophila hydei) spread sweetpotato black rot (Ceratocystis fimbriata) regardless of their population size. Wounding sweetpotatoes increases disease spread, and molecular diagnostics detect infections missed by visual inspection.

Area Of Science

Agricultural Entomology
Plant Pathology
Molecular Diagnostics

Background

Insect vectors are significant drivers of postharvest disease transmission.
Ceratocystis fimbriata causes sweetpotato black rot, spreading rapidly in storage.
Drosophila hydei flies can acquire and potentially transmit C. fimbriata.

Purpose Of The Study

To investigate if Drosophila hydei vector density affects Ceratocystis fimbriata transmission.
To develop molecular diagnostic assays for improved pathogen detection.
To understand the role of wounding in disease transmission.

Main Methods

Transmission assays with varying fly densities (10-80 flies).
Inoculum exposure and transfer to sterile agar and sweetpotatoes (wounded and unwounded).
Standardization of quantitative PCR (qPCR) assays using specific markers (T3G9, T5G26).

Main Results

Transmission occurred at all tested fly densities, indicating density-independent spread.
Disease incidence was significantly higher in wounded sweetpotatoes.
qPCR detected C. fimbriata DNA in flies and asymptomatic roots, revealing latent infections.

Conclusions

Drosophila hydei effectively vectors Ceratocystis fimbriata independently of density.
Wounding enhances disease transmission success.
Molecular diagnostics are crucial for detecting latent postharvest infections and informing management strategies.

Keywords:

Disease Control and Pest Management Fungal Pathogens Pathogen Detection