Pennsylvania Game News - April 2019 - 6

Pennsylvania WNV
Unusually wet conditions contributed to
2018 going down as the worst year on
record for WNV in Pennsylvania. By midsummer, researchers had collected five
times the number of positive mosquito
samples they detected during the same
period in 2017. There were a record 115
human cases. And for the first time, grouse
found dead in Penn's Woods - four of them
- tested positive for WNV. Despite that,
initial hunter-harvest data indicated grouse
might have fared better than expected.

n Both young forest availability and
WNV prevalence determine the fate of
grouse populations.
A 2017 Game Commission-Penn State
University analysis showed habitat and
WNV influence whether grouse persist in
an area, whether they colonize new areas,
and whether individual populations disappear over time. This gives us something
to work with! We now know our management efforts will be more effective if we
take disease prevalence into account when
managing habitat.

n Individual grouse in areas of highly
abundant and high-quality habitat might
have a higher chance of survival, based
on antibody findings.
Further, hunter-flush-rate data show
grouse populations in good habitat
rebounding more quickly after bad WNV
years, compared to populations in more
isolated or marginal habitats. This also
has valuable management implications.
n We're more knowledgeable about
the primary disease vectors, based on
a 2017-18 collaboration with the state
Department of Environmental Protection's West Nile Virus Surveillance
Program.
The mosquito Culex pipiens is the primary WNV vector in human residential
areas. But Game Commission trapping
shows it's rarely found in the state's forests. Rather, the vector we must target is
Culex restuans, a closely-related country
cousin of Culex pipiens that prefers to
target birds.
Our 2017-18 research shows Culex restuans thrives in woodlands, occurring in

Being thorough with science
To ensure we were not making assumptions about West Nile virus, and missing other
potential drivers of grouse populations, we
conducted a rapid string of focused investigations over the past two years.
These additional research projects have
helped us to eliminate other potential factors as suspects, and will help direct future
management decisions.
Most have heard of our ongoing study of
West Nile virus, but that's not the only disease
we're investigating.
Here are some others:

domestic turkeys in Europe and the Middle
East. Although it has not been identified in
domestic turkeys in North America, the virus
was first identified in a wild turkey with tumors
in 2009. Subsequent research has determined
the virus is common in wild turkeys throughout
the eastern United States. However, infected
wild turkeys only occasionally develop tumors
and most infections show no symptoms. To
check for potential grouse impacts, we collected leg bones from grouse hunters last year.
We tested the marrow and - great news - did
not detect the virus in any grouse.

Lymphoproliferative Disease Virus - This
virus has been found to cause tumors in

Parasites - We worked with Ted Phillips, a
biology professor at Gannon University and an

6
Pennsylvania Game News - April 2019

Table of Contents for the Digital Edition of Pennsylvania Game News - April 2019
