Chapters 1 - U.S. Fish and Wildlife Service

Management Alternatives
exceeded established mosquito threshold treatment levels (Table 1); and the species of
mosquitoes breeding on the Refuge pose an immediate threat to human health. Based on
these criteria, the actions that would occur under Phase 3 include: mosquito monitoring
throughout the breeding season; actions to reduce potential mosquito breeding habitat on
the Refuge per available funding; and treatment of mosquito larvae and pupae that is
compatible with Refuge purposes.
Phase 4. Phase 4 of the Mosquito Management Plan would include the use of an adulticide
to control mosquito populations on the Refuge. The following conditions must be met
before an adulticide could be applied on the Refuge:
A public health emergency has been declared by the Orange County Health Care
Agency (OCHCA) or the California Department of Public Health for an area that
includes the Refuge;
Infected mosquitoes have been identified on the Refuge or infected mosquitoes of
the species known to breed on the Refuge have been identified within the published
flight range of mosquito breeding areas on the Refuge;
The criteria established in the OCVCD’s Integrated Vector Management and
Response Plan (OCVCD 2010) for determining when treatment of adult populations
of mosquitoes (Table 3-3) should be considered has been exceeded on the Refuge
for the mosquito species of concern;
The FWS Integrated Pest Management Coordinator has approved the adulticide
proposed for use through the PUPs review process; and
The SUP issued to OCVCD has been modified by Refuge Manager to address
adulticide application.
OCVCD has coordinated with the Refuge Manager and Navy Environmental
Office staff on how, when, and where an adulticide would be applied on the Refuge.
Table 3-3
OCVCD Criteria for Considering Adulticide Application
Mosquito Species Criteria for Considering Treatment
Culex spp. 25 or more females per collection per trap night
Anopheles spp. 25 or more females per collection per trap night
Aedes spp. 1
5 or more females per collection per trap night 2
Culiseta spp. 10 or more females per collection per trap night
Multiple species 25 or more total female mosquitoes per collection per trap night
Source: (Orange County Vector Control District 2010)
1
Aedes is currently the only genus of mosquito known to breed on the Refuge.
2
The total number of trapped females is lower for Aedes spp. than other species of
mosquitoes because Aedes spp. demonstrated a limited attraction to CO2 traps. New
types of traps are currently being considered by OCVCD to more accurately establish
populations of Aedes spp. in Orange County (Jim Green pers. comm.).
To reduce the potential for additional applications of adulticide within a season, all
adulticide application shall occur in conjunction with the application of larvicides and
pupacides. In addition, adulticides shall only be applied using vehicle mounted or backpack
fitted ultra-low volume spray equipment and applications shall only occur along those
roads that extend along the northern, eastern, and western perimeter of the Refuge and
only when meteorological conditions are stable and favorable with a consistent wind
Draft Comprehensive Conservation Plan/Environmental Assessment 3-27