Vector Disease


Mosquitoes Playing Hard to Get? Consider Resistance Monitoring

Posted by The VDCI Team on Apr 10, 2018 2:19:53 PM

Written By Kellie Nestrud, Biologist and Contract Manager in Louisiana 


There are several different components of a successful Integrated Mosquito Management (IMM) program. The consideration of chemical resistance in the local mosquito population is one of the components. Knowing, understanding, and monitoring for chemical resistance should begin as early as possible in an IMM program. It is recommended that all IMM programs monitor their mosquito populations for resistance at the beginning of a season and as often throughout the season as thought necessary. Resistance data is most valuable when collected over time to allow for comparison and monitoring of trends. There are many methods to monitor the effectiveness of an insecticide, and program managers may need to adjust their approach from season to season.

The Centers for Disease Control and Prevention (CDC) defines that a population of mosquitoes is considered to be resistant to an insecticide if a mortality rate is less than 90%. So how would one know if they are working with a population that has resistance?
Read More

Topics: Integrated Mosquito Management (IMM), Surveillance and Disease Monitoring

Mosquito Surveillance – Part 2: Life at the Lab Identifying Species and Disease Testing

Posted by The VDCI Team on Nov 29, 2017 11:28:53 AM

Written By Michael “Doc” Weissmann, Ph.D., Chief Entomologist

As discussed in a previous Mosquito Surveillance blog post, a well-designed surveillance program provides important information necessary to guide a modern mosquito control program. However, trapping the mosquitoes is only the first step in surveillance. Once the mosquito specimens are collected, they must be processed in the laboratory.

lab-mosquito-identification-250x166.jpgOnce the sample is euthanized, the mosquitoes are counted to determine how many were captured. If the trap count is very high, the numbers are estimated and only a sample is identified. How high is high? In locations without mosquito control and with good sources of water, nectar, blood-meals, and harborage, trap counts in the tens of thousands of mosquitoes in one night have been recorded, and not just in the tropics!
Read More

Topics: Surveillance and Disease Monitoring, Integrated Mosquito Management (IMM)

Mosquito Surveillance – Part 1: The Art of Hunting Mosquitoes

Posted by The VDCI Team on Oct 30, 2017 2:17:22 PM

Written By Michael “Doc” Weissmann, Ph.D., Chief Entomologist

I may be biased, but in my opinion surveillance is the most critical component of the Integrated Pest Management method of controlling insect pests. In modern mosquito control programs, surveillance includes setting traps to monitor adult mosquito populations in a given area.

harvey-emergency-response-truck-surveillance-250x166-blog_TX-danm.jpgA good surveillance strategy includes choosing the right kind(s) of traps to use that meet the goals of the control program. For example, most female mosquitoes are attracted to carbon-dioxide given off by a breathing animal that would be a potential source for a blood-meal. A CObaited light trap utilizes dry ice or some other source of carbon-dioxide to mimic the breathing of an animal blood source, with a small light bulb to draw the mosquitoes close enough to the trap fan for capture. Egg-laying females of species that live as larvae in smaller, water-filled containers can be collected with Gravid Traps. These consist of a fan and net suspended above a container of “highly organic” water as bait (usually an infusion of fermented hay and other ingredients). Many mosquito species are attracted to light, and a New Jersey light trap draws them into a fan using a bright light as bait, but with the unfortunate side-effect of collecting many other species of flies, beetles, and moths that also come to lights – in some locations at certain times of year it can be quite a chore to pick through the non-mosquitoes that are also collected. Surveys for Aedes aegypti - the primary vector of Yellow Fever, Chikungunya, Dengue, Zika, and other viruses – and the related Asian Tiger mosquito (Ae. albopictus) often utilize BG Sentinel traps and lethal ovitraps to attract egg-laying females of these “container-breeding” species.
Read More

Topics: Surveillance and Disease Monitoring, Integrated Mosquito Management (IMM)

Mosquito Surveillance Traps: Are They All The Same?

Posted by The VDCI Team on Feb 23, 2017 1:06:46 PM

Written By VDCI Team

Why are there several different types of mosquito surveillance traps? Most mosquitoes are attracted to light, right?

Yes, many mosquito species are attracted by light; however, some species, including the notorious Aedes aegypti, prefer to feed in the day and early evening. This blog will provide a brief overview of four mosquito surveillance traps, each with its advantages, depending upon what specific information is desired. Adult mosquito surveillance programs include the weekly trapping of adult mosquitoes by dividing an area such as a city, county, or industrial facility into control zones and utilizing traps that are most meaningful in each zone. Understanding a community’s environment and history, along with the implementation of the right trap(s), will provide a better picture of the mosquito species in a given area and if a potential disease threat exists.

BG-Sentinel Trap BG-Sentinel trap was designed with two specific mosquito species in mind, Aedes albopictus (Asian Tiger mosquito) and Aedes aegypti (Yellow Fever mosquito). The two species are known to vector dengue, chikungunya, Zika, and yellow fever viruses and thrive in urban environments. Both species use natural and artificial containers for breeding, making them notoriously difficult to catch in significant numbers. The BG-Sentinel trap is made of a tarp like material, about the size of a 5-gallon bucket, and utilizes an attractant such as Octenol lure, human scent lure, or carbon dioxide (CO2). A funnel located at the top of the trap leads mosquitoes to an electric fan (outlet or battery powered) that pulls them into a collection net. The BG-Sentinel traps do well at catching the elusive Aedes species when placed in the proper areas and with the appropriate attractants.


Read More

Topics: Surveillance and Disease Monitoring, Public Education

Larval Mosquito Habitats

Posted by The VDCI Team on Aug 11, 2016 12:11:30 PM

Written By Tim Bennett, Vice President of Western Operations

flooded_salt_marsh_pan_Nantucket_Mosquito_Larval_Habitat_250.jpgMost people have heard the stories about mosquitoes being capable of using the tiniest amount of water as habitat in which to lay their eggs. There’s no doubt that many of these same people believe that such stories are often exaggerations because surely a mosquito would not really lay eggs in a bottle cap, right? Well, I can honestly say that I have seen exactly that, mosquito larvae wiggling around in a two-liter soda bottle’s lid, in a trash pile in Mississippi in 2004. No exaggeration, no embellishment, no joke.

Mosquitoes are easily some of the most adaptable and persistent animals on the planet. They are found on every continent except Antarctica, from the hottest deserts and rainforests to the icy tundra of the Arctic Circle. Essentially, if there is standing water with enough nutrients to sustain the development of their larvae, there is a good chance that mosquitoes will be there, and while some species have adapted to very specific larval habitats and environments, for others, almost any stagnant water will do. Thus, larval surveillance and habitat identification are key components of a successful integrated mosquito management program.

Read More

Topics: Surveillance and Disease Monitoring, Integrated Mosquito Management (IMM)

VDCI Assists CDC with Zika Virus in U.S. Territories

Posted by The VDCI Team on May 12, 2016 1:39:04 PM
Written By The VDCI Team
Marshall_Islands-1.pngVDCI began a contract with the Centers for Disease Control and Prevention (CDC) in April of this year. The partnership assists U.S. Territories with public health efforts by defending the population against the threat of Zika. As part of the partnership, VDCI team members have been active in the U.S. Virgin Islands, the Marshall Islands, and Guam.

Dr. Broox Boze, Operations Manager in Northern Colorado, discusses her recent work in the Marshall Islands.
Read More

Topics: Emergency Response, Surveillance and Disease Monitoring

West Nile Virus in North American Bird Populations

Posted by The VDCI Team on Apr 14, 2016 10:07:05 AM
Written By Broox Boze, Program Manager in Northern Colorado
West_Nile_Virus_Lifecycle.pngPrior to 1999, you had probably never heard of West Nile virus, and in fact, until then it was virtually unknown in the US. However, that year 62 human cases, 25 horse cases, and countless bird diagnoses were reported in New York state. Since that time the virus quickly spread throughout the country and has been documented in all of the lower 48 states, affecting more than 40,000 people. While the effects of West Nile virus on human populations have been studied in great detail, and we have a fairly good understanding of its impact on human health, we are only recently starting to understand how it can make changes to bird populations and the larger ecosystem.
Read More

Topics: Surveillance and Disease Monitoring, Mosquito-Borne Diseases

Larval Mosquito Surveillance and Control Methods

Posted by Daniel Markowski, Ph. D. on Sep 3, 2015 9:28:00 AM
Written By Tim Bennett, Vice President of Western Operations
kris_sampling_mosquitosLarval surveillance and control is a critical component of any effective Integrated Mosquito Management (IMM) program because when mosquitoes are eliminated prior to becoming adults, they cannot pose a nuisance or disease problem. In fact, larval mosquito control operations are often the largest and most extensive aspect of municipal mosquito control programs and are more important than ever for compliance with state and federal regulations. Below we outline six key components of a successful larval control program.
1. Larval Surveillance – Trained field technicians must inspect both known sources of standing water and any newly discovered standing water for the presence of mosquito larvae. When a field technician surveys these larval habitats, he/she uses standard dipping techniques to sample the water for the immature mosquitoes. If larvae or pupae are detected, the stage of development the larvae are in (Instar) and the number of larvae per dip is recorded, typically as an average of 3 – 5 dips per site. After the dipping takes place, the technician must determine the proper control measures that should be taken. Possible actions include: “No Action”, “Physical Control”, “Biological Control” or “Chemical Control”. 
Read More

Topics: Surveillance and Disease Monitoring

Mosquito Surveillance For Effective Mosquito Population Control

Posted by Daniel Markowski, Ph. D. on Aug 19, 2015 2:34:00 PM

Written by Cristina Flores, Regional Director

While most people believe that mosquito control is nothing more than truck or backpack-based applications of pesticide, in reality, spraying to control adult mosquitoes is just one small aspect of a well-managed integrated mosquito management program. In fact, the foundation of every effective mosquito control program is Surveillance.

What is Mosquito Surveillance and why is it necessary?
Mosquito Surveillance is the routine monitoring of both larval and adult mosquito populations over the course of an entire mosquito season. Such mosquito surveillance is critical to a successful municipal or commercial mosquito control program for several reasons:

1. Monitoring changes in mosquito populations 
2. Identifying which mosquito species are present
3. Detecting mosquito-borne diseases
4. Determining what control measures need to be conducted

Monitoring changes in mosquito populations is important because it allows mosquito control experts to track exactly where the larval and adult mosquito populations are rising or falling. These data, when compared to previous weeks or previous years, provides the knowledge we need in order to identify and predict perennial, sporadic, or new problem areas, as well as to predict possible increases in the risk of mosquito-borne diseases.

Read More

Topics: Surveillance and Disease Monitoring