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                   through community-based land conservation.

Japanese Barberry and Lyme's Disease Why we should be declaring war on Japanese Barberry


Japanese Barberry is an invasive species that has infested many natural areas in Tinicum Township.  A few years ago I had come across a study out of the University of Connecticut that found increased numbers of blacklegged ticks (Ixodes scapularis), often called deer ticks,  infected with the Lyme spirochete in forests with Japanese Barberry.  The numbers were striking.  The study showed that “ when they measured the presence of ticks carrying the Lyme spirochete they found 120 infected ticks where Barberry is not contained, 40 infected ticks per acre where Barberry is present but somewhat controlled and only 10 infected ticks where there was no Barberry.”  According to the study findings, Japanese Barberry creates a microclimate underneath the plant which keeps the area more humid than if there was no Barberry.  Ticks are susceptible to desiccation and must retreat to the leaf litter when it is dry.  With the more humid microclimate they can move around for longer periods and thus find a host more easily.  Blood meals are necessary for successful reproduction.  Another study released last May also from the University of Connecticut looked at the exposure rates for White-footed mice to the Lyme spirochete.  It found that due to this microclimate, especially the juvenile ticks were able to spend more time in search of a host.  They also found a lower diversity of hosts other than White-footed mice in forests that were compromised by the presence of Barberry and other invasives versus an intact forest.  Since the White –footed mouse is a competent host, meaning one that can transmit the Lyme spirochete, this resulted in a higher number of infected ticks in these forests that were filled with invasives, most especially Japanese Barberry.


The first study and those numbers were enough for me, I have been removing all Japanese Barberry from my property and will continue to patrol for new shoots.  It seems pretty clear to me that we should be doing all we can to remove this invasive both for the health of our forests and our own health.   — Dianne Allison



To read more about this study, visit the Entomological Society of America's website.



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