You may feel like the topic insecticide resistance is dynamic, complex, and ever evolving. In many ways, you’re right. As a vector control professional, you are challenged operationally every day to overcome resistance and successfully control mosquitoes. While this may be a new topic to some of us in vector control, it is a common theme across several entomological fields (such as agriculture and apiculture). To support you in your efforts to control mosquitoes, ADAPCO works to gather information and resources to better support your program’s needs for resistance monitoring and management.
So, what do you do if you think there is insecticide resistance in your area? How do you monitor for it and respond to it when it’s detected? With such an important topic, we wanted to take the opportunity to highlight programs in various regions throughout the US that have developed a resistance monitoring and management program to help them better control mosquitoes.
In the south-central region, we interviewed Chris Fredregill, Director for Harris County Public Health, Mosquito and Vector Control Division (HCPHMVC). Chris found his way to mosquito control while a student at Texas A&M. Dr. Jim Olson, a major proponent and supporter of the mosquito control industry, encouraged Chris to explore a career in vector control. Now, Chris manages a district that covers 1,778 square miles and protects 4.7 million residents from the public health threat of mosquitoes.
Since 1988, HCPHMVC has been monitoring resistance in some capacity. These efforts meant they were able to document resistance in their Aedes albopictus populations only a few years after their arrival to Texas. In 2000, they also found malathion resistance in some of their Culex populations, but after “resting” their organophosphate use for a few years, saw susceptibility recovered in those populations. Through collaborations, some external support, and prioritization of internal resources and expertise, HCPHMVC was able to establish a formalized and robust insecticide resistance management plan in 2005. Today, it continues to grow and evolve to address the important issue of insecticide resistance in mosquito vectors.
Harris County Public Health’s Approach to Monitoring and Managing Resistance
The insecticide resistance management plan at HCPHMVC is primarily focused on three species:
- Culex quinquefasciatus, the southern house mosquito
- Aedes aegypti, the yellow fever mosquito
- Aedes albopictus, the Asian tiger mosquito
These species are important from both a nuisance and public health perspective. To monitor the resistance in these populations, there are several sentinel sites and survey areas throughout the county where mosquitoes are collected and used for both field and laboratory testing. Resistance testing is managed by HCPHMVC’s entomologist who supervises two full-time technicians and a seasonal technician as part of the testing and evaluation team.