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Editor’s Note: This article originally appeared in Entomology Today, a project of the Entomological Society of America with the goal of reporting interesting discoveries in the world of insect science and news from various entomological societies. To learn more, visit www.entomologytoday.org.
In the past few decades, outbreaks of multiple mosquito-borne viruses have been popping up throughout North and South America. Some of these viruses are well known to the public, such as Zika, chikungunya and West Nile, while others such as Eastern equine encephalitis and Mayaro haven’t quite broached mainstream news cycles. Furthermore, other viruses that have been in the Americas a long time continue to cause problems, such as dengue and yellow fever.
But why have there been so many outbreaks, specifically of diseases new to the Americas?
While the reasons likely are myriad, a team of researchers from Brazil and Argentina propose several ideas in a paper recently published in the Journal of Medical Entomology.
In the article, the authors point to four main factors influencing the spread of mosquito-borne viruses.
1. A diverse mosquito and host fauna.
According to mosquitocatalog.org, 862 mosquito species can be found in South America, 462 in continental Central America and 192 in North America. Furthermore, the continents host thousands of species of birds and mammals, the primary hosts for mosquito-borne viruses. While not all of the mosquito species are vectors of diseases, such a large population offers the viruses ample opportunity to adapt to new vectors and infect new hosts.
2. Global warming.
Mosquitoes require external heat sources to regulate their temperature, so they are very dependent on climate to function. While the ecology of viruses and their vectors is complex, a warming climate could be one factor aiding vectors’ range expansion.
3. Increased international travel.
Mosquitoes and viruses have taken advantage of global travel for centuries. For example, the slave trade may have introduced yellow fever and dengue to the Americas. Later, the Asian tiger mosquito, Aedes albopictus, which is a vector of multiple viruses, arrived in the U.S. in ships returning from the Pacific theater of World War II. More recently, Zika is believed to have arrived in Brazil through an international canoeing competition or soccer’s World Cup.
In the past 50 years, the world’s population has grown by more than four billion people, and now more than half of those people live in urban areas. However, inadequate infrastructure in urban areas in developing or underdeveloped countries can create prime breeding sites for mosquitoes (such as rainwater collection containers in areas without a reliable water supply) and increase human contact with mosquitoes (such as in houses without air conditioning and with screenless windows).
The four reasons for the increase in mosquito-borne disease outbreaks in the Americas are broad, and the factors that influence each one are complex. Due to the complexities, preventing further dispersal of vectors and the diseases they spread isn’t an easy task. Attempts at control require broad integration of multiple control techniques and can differ greatly by species.
Some of the techniques the authors list that can be employed include:
Unfortunately, there are no easy answers for why outbreaks of mosquito-borne diseases new to the Americas continue to occur, and there are no easy answers on how to prevent/control them.
Because there aren’t easy answers, the authors argue that vigilance for diseases and their vectors is necessary for everyone, from mosquito-control professionals and doctors to people living in or traveling to areas where diseases are present. Furthermore, control efforts should not be abandoned or neglected after a disease is thought to be controlled but rather should be continued to prevent future outbreaks.
The author is manager of publications for the Entomological Society of America.
As temperatures rise with climate change, mosquito season extends past the summer months in many parts of the world. Some researchers have questioned how this lengthened season influences the risk of being infected with mosquito-borne diseases such as dengue, chikungunya and Zika.
Now, in a paper published on April 27, 2017, in PLoS Neglected Tropical Diseases, Stanford University researchers modeled how rising temperatures might influence mosquito behavior and disease risk around the world. The researchers also calibrated their model with field data on human infections of mosquito-borne diseases.
“Dengue epidemics have been on the rise in the past couple decades so there’s been a growing effort trying to understand why we’re seeing more dengue, and what the relationship is between dengue transmission and climate,” said study lead author Erin Mordecai, an assistant professor of biology.
THE IDEAL TEMPERATURE. Temperature controls several factors that underlie the time it takes for a virus to be transmittable to humans. These include how long it takes for a mosquito to ingest a virus during one feeding and then be ready to inject it in a later feeding; the length of the mosquito’s life cycle; and how often mosquitoes bite.
“All these traits rely on temperature, but they tend to be nonlinear,” Mordecai said. “They increase to a point and then drop off.” The group found that mosquito traits favorable to spreading disease peaked when temperatures reached 29°C (84°F), but were lower when temperatures were cooler or warmer.
When Mordecai looked at transmission of dengue, chikungunya and Zika in people, those results matched what her models predicted. She said that if you graph how transmission rates change with temperature, you get a bell-shaped curve peaking at 29°C.
PREDICTING FUTURE OUTBREAKS. Knowing the optimal temperature for disease transmission is critical for predicting future disease rates, Mordecai said. Before this study, she said, there was a wide range of temperature predictions from other researchers.
“If we’re predicting a 29°C optimum and another model is predicting a 35°C optimum, the other model will say that climate change will increase transmission,” she said, pointing out that if local temperatures are already close to the optimal temperature, infection may, in fact, go down as temperatures rise.
The information also can help predict how and where disease might spread with climate change. “We really want to build more predictive models that take climate information and make predictions about when and where we can invest in vector control to try to prevent epidemics,” Mordecai said.
This kind of planning is especially important in countries that have lower socioeconomic levels. “Concentrated urban poverty is really where you see a lot of vector-borne disease transmission,” Mordecai said. She explained that the mosquito that carries dengue, chikungunya and Zika is an opportunist — it will breed in any water container it can find, from bottle caps to water storage basins. “You tend to see a lot of people exposed to a lot of mosquitoes in places where access to piped water is not reliable, because storage basins are where people are storing water.”
Mordecai knows there is more work to be done with mosquito-borne illnesses. “There’s lots of discussion about what’s going to be the next thing. What’s the next Zika?” She said this model will help researchers predict when and where transmission of the next Zika might happen — and allow enough time to prepare for the event.
Other authors on the study include Prithvi Gudapati and Marta S. Shocket of Stanford; Jeremy M. Cohen, Michelle V. Evansc, Leah Johnson and Jason R. Rohr of the University of South Florida; Catherine A. Lippi and Sadie J. Ryan of the University of Florida; Kerri Miazgowicz and Courtney C. Murdock of University of Georgia College of Veterinary Medicine; Van Savage of University of California Los Angeles; Anna Stewart Ibarra of SUNY Upstate Medical University; Matthew B. Thomas of Penn State University; and Daniel P. Weikel of University of Michigan.
The research was funded by a grant from the National Science Foundation — Ecology and Evolution of Infectious Disease. Source: Stanford News Service
“As pest management professionals it’s our responsibility to look out for our customers, their pets and the environment from the impact of mosquitoes,” Chris Swain, technical services manager, MGK Insect Control Solutions, told attendees at this year’s MGK Mosquito Conference in Houston.
The goal of mosquito control is to allow homeowners to enjoy their yards without the annoyance or health risks associated with mosquitoes, including the Zika and West Nile viruses. Mosquitoes, compared to any other animal, pose the greatest health risk to humans, of which the U.S. population has become increasingly aware. “Customers are thinking about a lot of things when they pick up the phone and call you for mosquito control,” said Swain.
Mosquito control has obvious advantages for customers and it can also be a good revenue source. “Year-over-year, mosquito control is continuously going up,” said Swain. “More and more people are looking for mosquito control.” It has the elements needed for increased revenue: low equipment maintenance, minimal product costs and it isn’t labor intensive.
“I think there’s a hidden profit for a lot of companies that have been providing mosquito control for a number of years,” Tommy Powell, technical field representative, MGK, told that same audience. “They’ll likely notice a decrease in callbacks, because they’re going out to customers regularly to treat for mosquitoes.”
In addition to residential work, there are commercial opportunities for providing mosquito control, including recreational areas, weddings, sporting events, churches and restaurants. Tent rental companies are a natural partner for prospecting mosquito control business.
EQUIPMENT ESSENTIALS. Backpack mist blowers are Swain’s application equipment of choice for mosquito control. They’re effective, provide the best coverage, use about one-third less product compared to a truck-mounted sprayer, there’s no dripping and there are no hoses to drag. Another advantage of backpack mist blowers is being able to easily treat the underside of foliage, because of the forced air. Technicians may forget to turn the sprayer wand upside down to treat the bottom of leaves. Using a mist blower eliminates that problem.
If you encounter a well-groomed yard or outdoor area with a built-in grill, wood fireplace, lighting and dining table/chairs, you know the homeowner is using the space a lot. Areas like these are generally inappropriate for using a backpack mist blower. There are too many items to avoid and too many opportunities for drift. “Any tight areas, a hand-held, pump-up sprayer comes in handy. You can directly target areas for treatment and avoid drift,” Powell said.
Mosquito misting systems are another option. Since many biting insects are active at night, the systems can be set to treat during the evening and nighttime hours. You can, however, recommend the system treat during the day depending on your customers’ mosquito prevention needs. Mosquito misting systems provide this type of flexibility.
THE RIGHT PRODUCT MIX. There are two factors for choosing the right product for a job: one is the product characteristics, and the other is how often you’d like to schedule treatment. “Pest management professionals have different choices for products and they use them for a number of different reasons,” said Swain. “Some people look for products that have short residual, others look for long residual. Some people want to go back out in a week—others every two, three or four weeks. So product choice is based, in part, on what you’re trying to accomplish. It goes back to meeting your customer’s expectations.”
Swain recommends using a tank mix of adulticide — an insecticide that kills adult insects — and an insect growth regulator (IGR) for preventive pest control, as contact with the IGR can prevent the development of viable eggs or prevent pupae from emerging as adults. “If the IGR is going into standing water, it typically needs to be applied by itself, because you’re not supposed to spray standing water with a pyrethroid-based insecticide,” explained Swain. “You could put the IGR in a separate sprayer. Make sure you read the technical label.”
“Initially, mosquitoes are going to die from the adulticide,” said Swain. “The IGR will stay on the foliage after the adulticide loses its effectiveness, so the mosquitoes have the opportunity to pick it up later.”
“We also recommend PBO (piperonyl butoxide). It’s used to treat MFO-based (multifunction oxidases) resistance — a genetic resistance,” added Swain. “You can also add surfactants, which tends to help with penetration of the cuticle.”
OBSERVE AND DETERMINE. Conducting a thorough inspection will provide you with the information you need to develop a treatment strategy and the cost of treatment. During the inspection, identify breeding and harborage sites, areas to avoid, and which equipment and products to use — all necessary to determine the cost of treatment.
There is technology at our fingertips, but it may not always be the best solution. “Some people use Google Earth and won’t even go out to the house to provide an estimate,” said Swain. “I’m old school. I like to go to a house. It’s tough for me to see what I’m getting into if I’m physically not there.
“I take notes during the inspection so I can have a conversation with the homeowner about what I found. I’ll go over everything I’ve learned, talk about conducive conditions and listen to gauge their feedback,” said Swain. “I want to make sure they understand what I can deliver.” If customers don’t have realistic expectations, you’ll likely get repeated callbacks from dissatisfied customers — a cost in terms of time and labor.
“If there’s a creek out back, which is a continuous conducive condition, I explain that it’s an area I can’t treat and that adult mosquitoes will be emerging daily. I’m probably not going to be able to get 80 percent control, if that’s what they expect,” said Swain.
The post-inspection conversation is also your opportunity to informally interview customers and determine if they’re going to be a good fit. If their expectation of successful mosquito control is unrealistic, they may not be the best customer for you.
PREP TIME. “Pre-treatment is usually a walk around the property to see what areas you’re going to treat and to remove unnecessary items,” said Swain. Check wind direction to help avoid potential drift issues. Remove everything that should be excluded from treatment, from tables, chairs and flip flops, to toys and the dog’s water bowl.
Pick up everything you can before you begin treating. “It’s difficult to pick up a toy with a three-gallon sprayer on your back,” said Powell. “You have to take off the sprayer, pick up the toy and half way around the yard you’re going to find something else that needs to be picked up.”
This is the time to empty anything that has collected standing water. “You’ll be able to identify what you can dump and what you can treat,” said Swain. “Things like children’s swimming pools, tires or other items collecting water — dump them out. There’s no need to treat it with a larvacide if the water can be removed.” Before treating other areas of standing water, be sure it doesn’t run off into an active waterway. It’s critical to always use products according to label instructions.
“While I’m walking around, I’m also determining what equipment to use. Backpack mist blowers are one of my favorite pieces of equipment,” said Swain. An average 5,000-square-foot yard typically can be treated using a 3.7-gallon backpack mist blower. “I’ll use a power sprayer if I’m treating a large area, like three to four acres. I don’t want to keep filling up my backpack sprayer, so I’ll use a truck-mounted, 25- to 50-gallon sprayer and deal with pulling the hose around. That’s another reason I like the backpack mist blowers — there’s no hose to deal with.”
Be on alert for decorative ponds, fruit trees and vegetable gardens. “As a general rule, treat 20 feet away from a pond — be more safe than sorry. If you get it in the pond you’re going to kill the fish — all of them,” said Powell.
To avoid issues with product drifting into backyard ponds, some companies cover them with a tarp. They place a large “X” on the side of the tarp that always faces up, so that the wrong side isn’t accidentally placed on the water at the next job, causing the problem you’re trying to avoid. It’s safe to treat around swimming pools when done correctly, said Swain. “We try to have our backs toward the swimming pool and treat in the opposite direction of the pool, not towards it. It also depends on which way the wind is blowing.” Some companies use tarps to cover pools for safety.
Common sense prevails when it comes to what not to treat. Areas you absolutely must exclude from treatment include: natural bodies of water; surface water, like ponds; wetlands; food surfaces; fruit and nut trees; vegetable gardens; and anything that isn’t on your customer’s property.
“I teach technicians that if they don’t know what a plant is, assume it’s an edible,” said Powell. If you spray pyrethroids on a tomato plant, for example, the fruit can’t be eaten and the plant should be removed. You’ll be purchasing your customer a replacement plant. “If it’s not on the label, it’s a legal issue at that point,” said Powell, “With one product you may be able to treat around a fruit tree, but you can’t treat it directly.”
Don’t forget to look in the neighbors’ yards to check for kids, pets, gardens and anything else that could be problematic.
TREATMENT. “We focus on treating vegetation,” said Swain. “Mosquitoes rest on vegetation 90 percent of the time.” Treat all mosquito resting and breeding sites, including: shrubs; overgrown or non-mowed grass; standing water; and areas with little or no air movement, such as soffits, and entry areas. The target area is from 6 inches to 20 feet vertically. “You’ll find Culex mosquitoes higher than 20 feet, but they’re not as likely to bite like other mosquitoes,” said Powell. Focus on the lower portion of trees. Check for animals that may be hiding in tree holes before treating the tree.
IGRs can be used in water that’s contained, such as decorative fountains. If the water flows into a water source — or if you’re not certain if it does or not — don’t treat it with an IGR. “Avoid any kind of active, natural waterway. If it’s got fish, you shouldn’t treat it,” added Swain.
“I’ll treat the grass when I’m walking around, especially if it’s unmowed, but I don’t spend a lot of time on it,” said Swain. “Some people don’t treat the grass and focus only on the high vegetation.”
Communicate with your customer the importance of keeping people, pets and sprinklers off treated areas until the product is dry.
POST-TREATMENT. “Post-treatment is going to vary by company and how they do things. We generally recommend going back in a week or two. Some don’t go back out at all, while others go out every week or two,” said Swain. “Be aware of product retreatment intervals, so you know how often you can use a product. And most important, continue to communicate with your customer.”
Customers should be included in your post-treatment plan. Talk to them about their involvement in controlling mosquitoes, such as eliminating sources of standing water, trimming excessive vegetation and other ways they can help keep the population down.
IN SUMMARY. Mosquito control services provide customers with what they want and need: a yard they can use with minimal annoyance and risk of mosquito-borne diseases. For you, it’s another revenue source with minimal requirements to begin treatments.
The author is owner of Perspective Communications and can be contacted at firstname.lastname@example.org.
By Lisa Lupo
Whether you are thinking about adding a mosquito control program to your existing offerings, or you’d like to improve the program you have in place, the advice and tips presented in the 2016 PestWorld session, Mosquito Business Models: What Works and What Doesn’t, can help your program take flight.
The session was presented by Donnie Blake, OPC Services, Louisville, Ky.; Dennis Jenkins, ABC Home and Commercial Services, Dallas-Fort Worth, Texas; and Bryan Cooksey, McCall Service, Jacksonville, Fla. The trio discussed the similarities and differences regarding the sales and service practices of their respective programs.
A DIFFERENT SPECIES. The greatest change with mosquito control programs in many areas of the U.S. is the rise of the Aedes aegypti mosquito and its transmission of the Zika virus. This is primarily because the behavior of these mosquitoes differs from that of Culex mosquitoes, which had been the primary U.S. mosquito species. Aedes mosquitoes tend to be most active during the day — in contrast to the dusk-to-dawn activity of Culex, and they lay their eggs singly, rather than in the groupings of the Culex. That said, both species are attracted to and lay their eggs in standing water; can transmit disease to humans through their bites; tend to rest in shaded areas; and are most active, to varying geographic degrees, from spring to fall. Thus, some practices can help decrease the presence of both species, while others must specifically focus on one or the other.
As all the presenters agreed, a significant factor in the effectiveness of any mosquito program is customer education and cooperation. Customers have to understand where and why mosquitoes breed, and that they cannot be completely eliminated. Additionally, they must cooperate in the mosquito management effort by following technician recommendations and advice, such as reducing standing water, keeping lawns mowed, etc.
“You really have to get them to help you or they will cancel because they think what you do doesn’t work,” Jenkins said. “It’s not a magic bullet — they will still have mosquitoes.” As such, “we never guarantee the absence of anything,” Jenkins said. “We provide a warrantied service — if and when mosquitoes come back, we’ll come back.” But, he added, “You can reduce your cancellations by continually educating and setting expectations.”
SERVICE. Mosquito service provides a good opportunity for pest control companies because of its low capital cost. Both the backpack equipment and products are relatively inexpensive, and mosquito service can be bundled with regular service, adding only 15-20 minutes onto most calls. Following are some specific opportunities and challenges the companies have seen in their mosquito control programs:
The technician. One challenge OPC faces is its need for dedicated mosquito technicians because of the specialty nature of the work, the backpack equipment used, and the full protective clothing needed to guard against product irritation. “It’s highly inefficient, we get that, but our normal technicians who do our Four Seasons program — our normal pest control program — the majority wouldn’t be able to do this mosquito control work,” Blake said. It also can be more challenging in states that require specific licenses for this work. “So, our ability to grow our mosquito management program is completely related to being able to get the people who can and will and enjoy doing this type of work,” he said.As a company located in Florida, McCall also faces issues of licensing, as well as mosquito service being deemed a public health activity. While the state handles night spraying, pest companies take responsibility for day service, Cooksey said. But if mosquito service is added on for a current customer, it can be done under the structural pest control rule; if it is for a new customer with no other service, it requires a public health certificate.
Not having such issues at ABC, Jenkins said, “We have technicians who want to do it, so ours are not just specialists. This also enables us to provide this service on a wider scale. Each of our pest control maintenance customers have the ability to add this service at any time, and scheduling is easier due to having the same technician perform both services.”
Inspection. Each of the three speakers noted inspection as a critical aspect of service, which must be conducted prior to any application. The inspection will not only reveal the mosquito species present — thus determining the application — but it will also identify any pollinator plants that must be avoided or treated when pollinators are not around.
Equipment. While backpack sprayers are available in different sizes, the majority opinion of those on the panel was that small backpacks, because of their lower weight and targeted application capabilities, are the equipment of choice.
Application. Another behavioral difference with Aedes mosquitoes that has a critical impact on service application is their tendency to live near a home. As Jenkins said, “The Aedes mosquito’s preferred food sources are you and me”; thus, the most effective application is low-flow up to the underside of plants around the home, beneath decks and porches, and under covered garages and sheds. He also recommended that briquettes be used in non-drainable standing water. However, technicians need to take care to avoid treating pollinator plants and to take weather into consideration.
Callbacks. OPC will reschedule mosquito service if there is even the threat of rain, Blake said. This is primarily because customers will often request retreatment if a rain event follows service — even if they didn’t find the service to be ineffective. In Dallas/Fort Worth, however, ABC will treat if there is a threat of rain — then retreat if needed, because, Jenkins said, “There is always a threat of rain.” In addition, since the application is designed to treat the underside of plants, only heavy rains would affect the treatment. Thus, they simply tell customers, “If you have a problem, please let us come back and do a retreatment. That retreatment policy is critical to setting the expectation.” Similarly, at OPC, Jenkins said, “Retreatments are included — and expected.”
SALES. A key advantage of mosquito work is that it can be sold by phone — as is the case with the three companies. The cost is estimated according to the homeowner’s description and a look at the property on Zillow.com, then any differences can be determined once the technician arrives at the home — which is another reason the pre-service inspection is critical.
“The mosquito program is probably the one that we have the highest renewal rate,” Blake said. “Without question, everyone wants to renew. In fact, if they haven’t heard from us by (the Kentucky) Derby, they call us.”
For ABC, mosquitoes provide a highly repeatable service. In fact, Jenkins said, “I’m gonna call you in March and assume you’re keeping the service — just like I do all my services. I’ll keep coming until you tell me to go away.”
To increase sales, Cooksey recommended companies become the local expert, taking out ads, leaving brochures for customers, publishing blogs, giving talks, etc. “The best price move for us was being sponsor of mosquito alert on our local news weather report,” he said, adding, “Our playground with mosquitoes is changing. We need to become more of a public health company as well as an insect control company.”
While none of the presenters revealed specific pricing information, Jenkins did note that ABC uses a three-level pricing structure — small, medium and large — with no charge for callbacks.
Contact the author at email@example.com.