A Low-Cost Spore Trap Allows Collection and Real-Time PCR Quantification of Airborne Fusarium circinatum Spores

Abstract

A variety of commercial instruments are available for sampling and quantifying microscopic airborne organisms from the environment. Although most samplers are highly sensitive, they are also expensive, costing thousands of dollars per unit, a price that is out of reach for many researchers, especially those looking to design experiments with replication. While looking at options to monitor pine stands for the presence of Fusarium circinatum, the causal agent of pitch canker disease, on multiple sites with several units per site, we developed a simple, low-cost spore trap that allows surveying spore abundance in outdoor environments. The trap consists of a rotating motor that holds a metal rod and two petroleum jelly-coated microscope slides. As the motor rotates, the slides collect airborne particles. To test whether the traps allowed detection of F. circinatum spores, we placed six traps on three sites: an actively-managed slash pine commercial stand located in Lake Butler, FL, a semi-managed loblolly and slash pine stand near Gainesville, FL, and a site with little perturbance at Goethe State Forest, FL, consisting of mainly slash pine trees. The slides were replaced weekly, and F. circinatum was detected by quantitative PCR using species-specific primers. Results show detection of low levels ( X ¯ = 1.7–77.1 picograms ± SE = 0.3–39.7) of the pathogen spores with high reproducibility. These traps offer a low-cost solution to spore, pollen, or small insect trapping experiments for initial or general assessment of a pathogen or species population. Their low cost has the added benefit that multiple traps can be deployed per experiment, thus increasing statistical power by using multiple replications.