Tuesday, 26 December 2017

Fungal spore 'death clouds' key in gypsy moth fight

A fungus known to decimate populations of gypsy moths creates 'death clouds' of spores that can travel more than 40 miles to potentially infect populations of invasive moths, according to a new study.

The study describes a new method for tracking the geographic range of this airborne insect pathogenic fungus from areas of a disease outbreak.

Better understanding of the distances these killer spores travel could help researchers correlate the fungus' range with weather patterns to better predict how bad gypsy moth damage will be in a given year.

The fungal pathogen (Entomophaga maimaiga) first appeared in New England in 1989 and only infects gypsy moths. The pollen-sized spores stick to caterpillars when they walk over them. Once attached, a spore uses enzymes to create a hole and enter the caterpillar's body, where a cloaking mechanism allows the fungus to remain undetected by the moth's defenses. Over four to six days, the fungus multiplies and then kills the host, after which new spores are literally shot from the cadaver into the air, where they become windborne.

From May through June, when gypsy moth caterpillars are feeding and before they pupate, the fungal pathogen can run through up to nine infection cycles, while the numbers of infections increase dramatically. During the study, the researchers found the peak caterpillar death rate due to E. maimaiga reached 86 percent, meaning that if you found 100 caterpillars munching leaves that day, 86 of them would die within the week.


Tonya D. Bittner, Ann E. Hajek, Andrew M. Liebhold, Harold Thistle. Modification of a Pollen Trap Design To Capture Airborne Conidia of Entomophaga maimaiga and Detection of Conidia by Quantitative PCR. Applied and Environmental Microbiology, 2017; 83 (17): e00724-17 DOI: 10.1128/AEM.00724-17

Posted by Dr. Tim Sandle

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