Modification of a Pollen Trap Design To Capture Airborne Conidia of Entomophaga maimaiga and Detection of Conidia by Quantitative PCR

Abstract

The goal of this study was to develop effective and practical field sampling methods for quantification of aerial deposition of airborne conidia of over space and time. This important fungal pathogen is a major cause of larval death in invasive gypsy moth () populations in the United States. Airborne conidia of this pathogen are relatively large (similar in size to pollen), with unusual characteristics, and require specialized methods for collection and quantification. Initially, dry sampling (settling of spores from the air onto a dry surface) was used to confirm the detectability of at field sites with deaths caused by , using quantitative PCR (qPCR) methods. We then measured the signal degradation of conidial DNA on dry surfaces under field conditions, ultimately rejecting dry sampling as a reliable method due to rapid DNA degradation. We modified a chamber-style trap commonly used in palynology to capture settling spores in buffer. We tested this wet-trapping method in a large-scale (137-km) spore-trapping survey across gypsy moth outbreak regions in Pennsylvania undergoing epizootics, in the summer of 2016. Using 4-day collection periods during the period of late instar and pupal development, we detected variable amounts of target DNA settling from the air. The amounts declined over the season and with distance from the nearest defoliated area, indicating airborne spore dispersal from outbreak areas. We report on a method for trapping and quantifying airborne spores of , an important fungal pathogen affecting gypsy moth () populations. This method can be used to track dispersal of from epizootic areas and ultimately to provide critical understanding of the spatial dynamics of gypsy moth-pathogen interactions.

A pair of native fungal pathogens drives decline of a new invasive herbivore

“…B. major forms rhizoids to hold cadavers in place and then actively ejects relatively short-lived primary and supernumerary infective spores. Conidia produced by entomophthoralean fungi can become airborne and travel longer distances (17). B. bassiana neither forms rhizoids nor actively ejects spores, but cadavers become densely covered with persistent spores that can be spread by direct contact and rainsplash (18).…”

Fungal Spore Richness and Abundance of Allergenic Taxa: Comparing a Portable Impactor and Passive Trap Indoors and Outdoors in an Urban Setting

“…Higher richness for passive traps outdoors resulted in lower I/O ratios of richness compared to active samples. Detection of rare taxa collected earlier in the sample period is contingent on DNA preservation, which was found to be significantly reduced by day two for Entomophaga maimaiga conidia on a polypropylene surface exposed in a field [ 40 ]. UV light exposure and rainfall are among the factors influencing the preservation of fungal spores collected on passive traps outdoors, requiring an apparatus to shield dry deposition-based passive traps if they are to be used in the field.…”

Population spatial synchrony enhanced by periodicity and low detuning with environmental forcing

“…Longerrange movements via human activities or entrainment in storms are possible [54][55][56], but are sporadic and rare. It is possible that movement of gypsy moth pathogens [57] or parasitoids could contribute to synchronization across this scale.…”