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HomeMy WebLinkAbout2013 BMP-NO ANDOVER Com monbnaltb of l.aooatbuotto STATE RECLAMATION AND MOSQUITO CONTROL BOARD MN " NORTHEAST MASSACHUSETTS MOSQUITO CONTROL AND WETLANDS MANAGEMENT DISTRICT , 261 Northern Boulevard,Plum Island a '` Newburyport,MA 01950 , Phone: (978)463-6630/Fax:(978)463-6631 Nf www.nortIiE;,, .s[m,l .sdmosgLiito.com Commissioners: Jack A.Card,Jr.:Director John W.Morris,CHO: Chair William Mehaffey,Jr.: Operations Manager Vincent J.Russo,MD,MPH: Vice Chair Emily D.W.Sullivan: Wetlands Project Coordinator Peter Mirandi,RS,MPH Esteban Cuebas-Incle,Ph.D.:Entomologist Joseph T. Giarrusso,Conservation Officer Robyn A.Januszewski:Biologist Paul Sevigny,RS,CHO Best Management Practice Plan North Andover Draft: 12/29/00; Revised: 3/013/04 11/04 6/7/06 1/07 1/08 1/09 1/10 1/11 1/12 4/13 Mosquito/Arbovirus Surveillance Summary Introduction Although fifty-one species of mosquitoes are found in Massachusetts, only about a dozen are of concern to public health. Their biting activity has been torturous throughout human history, often causing great misery to anyone living anywhere near a marsh or a swamp. Their biting activity has often had severe impacts on local economies by impeding outdoor work, attacking livestock, and frightening tourists. However, it's their ability to transmit viruses that cause painful, debilitating, and fatal diseases that has become a primary concern. Thus, it is crucial now more than ever that local mosquito activity and abundance are monitored and addressed to help protect a community's health and economy. Vigilance on mosquito activity and abundance is the mission of the Northeast Massachusetts Mosquito Control and Wetlands Management District. We possess the expertise to track mosquito populations, the protocols to have mosquitoes tested for viruses, and the experience and equipment to manage populations. Our District's mosquito control operations have evolved from exclusively "nuisance control"to principally "vector management". With "vector management", our surveillance and control strategies are designed to identify, monitor, and regulate mosquito vectors of principal arboviruses. "Arboviruses" comes from "arthropod-borne viruses"; in northeast Massachusetts these arboviruses include West Nile virus (WNV) and Eastern Equine Encephalitis virus (EEEV). See the accom- panying 2013 Vector Management Plan (VMP) that describes our District-wide tactics and strategies for monitoring and responding to the vectors of the aforementioned viruses. The Best Management Practice Plan presented here begins with summaries of mosquito and arbovirus activity this past season in both the District and your community. This will be followed by an operational summary, then preliminary plans (and costs) for surveillance and control in your municipality, as agreed upon with your Board of Health, for 2013. 2013 Best Management Practice Plan:North Andover Page 2 Northeastern Massachusetts The Northeast Massachusetts Mosquito Control and Wetlands Management District has thirty-two subscribing municipalities, thirty in Essex County and the remaining two in Suffolk County. Our basic surveillance program is designed to collect data on mosquito populations and diversity from at least one fixed"historical trapping station" (HTS) at each member municipality. The same fixed location is used every year and each station has two kinds of traps. The surveillance program runs from the beginning of May until the beginning of October. There are two collections per week from all the HTS's. Another type of surveillance trap, "resting boxes"is employed at fixed locations in habitats where EEEV is either suspected or has been found in the recent past; collections are made from the boxes twice a week. In addition, temporary traps are set at various locations in selected municipalities throughout the season when vector species are assumed to be in greater abundance and dispersal and/or when presence of viruses is suspected. These temporary traps are designed for one or two- day collections and may be deployed primarily in residential, school, and public-use areas. Des- criptions and photographs of all the traps employed can be found in the accompanying VMP. The 2012 mosquito surveillance season was our longest ever, lasting from 30 April through 3 October, for a total of 23 weeks. Also, more temporary traps were set than ever before. As our protocols dictate, all mosquitoes collected were identified, tallied, and key species were sent to the State Lab to determine if they were carrying WNV and EEEV. Well over a thousand samples or "pools"were sent for testing; do not confuse a"mosquito pool"with a small body of water called a "pool" (we do not invent the terms!). This past season was one of the most unusual ever experienced by our program. While fewer mosquitoes were collected in 2012, apparently far more individual mosquitoes were infected by either EEEV or WNV. There were more arboviral detections in mosquitoes than ever previously reported. Furthermore, there were two "pools", each with less than five mosquitoes, which tested positive for both viruses! As to effects on District residents, no infections from WNV were reported. There were, unfortunately, two fatalities from complications caused by EEE. The effects of the season-long drought took its toll on overall numbers of mosquitoes collected. Whereas over 78,000 mosquitoes were collected District-wide (not including additional temporary trappings)in 2011, only over 62,000 were collected in 2012. Twenty-two District municipalities experienced significant (i.e., greater than 10%)reductions in all mosquitoes collected as compared to 2011, one had no change, and nine had increases. Increases observed were due primarily to increases in cattail swamps mosquitoes. The rationale behind these population changes will be discussed below. For those who believe that our counts of mosquitoes are a gross underestimation of total mosquito presence, we wish to remind readers that our focus is to collect a representative sample of mos- quitoes in a city or town. Our job is not to collect the most mosquitoes possible or collect exclu- sively from known breeding areas! We want to collect as many mosquitoes as possible in areas where substantial portions of municipality residents live because we need to determine whether these mosquitoes are transmitting viruses dangerous to people. Human impact on natural mosquito- breeding habitats may dramatically lower their populations but, if there is an unusual rise in populations in residential areas, then you know something indeed is going wrong! 2013 Best Management Practice Plan:North Andover Page 3 The dry winter and spring affected the"Spring-brood"mosquitoes the most; these mosquitoes usually emerge in May through early June. Floodwater mosquitoes also comprise this "Spring- brood", but they will also emerge later in the summer and early fall after significant rain events. This was not the case in 2012; with the lack of significant rainfall, flood-water mosquito populations declined overall by over 80% compared to 2011 populations. The drought kept these mosquitoes as eggs and the occasional localized heavy rainfalls did not result in persistent standing water to allow the bulk of these mosquitoes to hatch or achieve adulthood. Salt-marsh mosquito populations remained at about the same levels as in 2011. We continued applying the bacteria Bacillus thuringiensis to the salt marsh immediately after the monthly spring tides and only when larval sampling indicated that newly-hatched populations were extremely abundant. Three aerial applications (only via helicopter)were made in 2012, followed by selected localized hand-treatments where necessary. The larvae consumed the bacteria and were soon dead. Applications were made at designated locations from Ipswich through Salisbury where historically, the bulk of adults have emerged. One of the species,AL cantator, continues not only to be the dominant salt marsh mosquito in Essex County, but continues to be found in more of our traps away from the salt marsh. They can fly at some distance from the salt marsh in search of blood, but they can also "breed"in more locations away from salt marshes. Their larvae develop in water anywhere from less brackish to almost pure freshwater, thus they can expand their range deep into Essex County. This species is of concern because they has been reported in other areas of the country infected with WNV; the potential expansion of another WNV vector into a WNV-"hot zone"is a major concern. We will continue to monitor its abundance and distribution. A species historically associated with the salt marsh is Culex salinarius. Although it will "breed" at the upper reaches of salt marshes, it can develop in practically any type of standing freshwater. Its population dynamics are heavily determined by rainfall and ground hydrology, as well as biotic factors such as competition with other mosquito species. There was a marked decrease in the total numbers for this species District-wide and it is assumed that drought was the cause of this decline. This species is of concern because it is considered to be the best vector of WNV in the northeast United States. Rarely reported in the past ten years, is another salt marsh species,AL taeniorhynchus. This year, this species has made multiple appearances in several of our traps abutting the salt marsh, albeit infrequently and in very low numbers. This species, another notorious human-biter, is found great abundance from south of Cape Cod along the Atlantic and Gulf coasts. If this species continues to make more regular appearances in our District, it may be a result of long-term climate change generated by increasing atmospheric temperatures. Another species whose spread into Massachusetts may be influenced by increasing atmospheric temperatures is the Asian tiger mosquito,AL albopictus. It has been repeatedly found in Bristol county the past two years, although infrequently and in very low numbers. It has not yet become established in Massachusetts and has been found only because its eggs are being transported into Bristol County. The eggs enter via used tires coming from albopictus-infested areas of the country. The tires fill with rainwater, the eggs hatch, and larvae develop into adults. Several specimens were found in Merrimac on one occasion in 2007, but not found again since (although we have tried searching!). This species is a ferocious human-biter and is an efficient vector for several arbo- viruses, including Dengue virus. Although this is a temperate species, it had been assumed that Massachusetts winters were too cold for its hibernating eggs to remain viable. If subsequent winters 2013 Best Management Practice Plan:North Andover Page 4 are similar to previous recent winters, hibernating eggs may survive and AL albopictus may become a permanent resident in Massachusetts. Tree-hole and other natural-container breeding mosquitoes remained at low levels throughout the District in 2012. Freshwater Anopheline mosquito populations remained low as well. These include mammal biting AL japonicus, AL triseriatus,Anopheles punctipennis, and An. quadrimaculatus which are more common in suburban to rural areas rather than urban habitats. The Cattail swamp mosquito, Coquillettidia perturbans is a species whose survival is dependent heavily on local hydrology to provide a stable habitat for development. As its common name implies, it is a species that"breeds"in cattail swamps and similar standing freshwater habitats. It is also an aggressive human-biter. Larvae hatch typically at the end of the summer and slowly grow and develop throughout the winter and spring. Lack of sufficient snow-melt water and spring rains should have reduced water levels of these bodies reducing the habitats available for successful development. The result should have been a dramatic decrease in their overall populations or at least remain at last year's levels. Instead, their populations increased District-wide by over 65%! Large increases were observed in fourteen municipalities while ten others showed no significant change (we define a change as significant if the more recent population increased or decreased by more than 10% from the previous year's population). This evidence lends one to think that either the drought had no effect(which is theoretically not possible given the biology of this species) or that the drought was insignificant and that the swamps that "bred"these mosquitoes were consistently flooded. If the latter hypothesis is the case, what can be causing the persistent flooding? One answer may be beaver impoundments which have increased in abundance and distribution in the District in the past decade. Beaver impoundments may also be creating or bolstering swamps where the EEEV vector, Culiseta melanura, readily breeds. Overall, the populations of Cs. melanura, the Cedar swamp mosquito, declined this year, which was not a surprise given the season-long drought. These mosquitoes normally survive the winter as larvae (living inside crypts in swamp tree hummocks)but when water levels reduce, the crypts dry and larvae die. This helps explain the low numbers of adult Cs. melanura recorded this year at most of the traps set at their preferred habitats (at or near cedar and red maple swamps). However, at two locations (in Hamilton and Topsfield) were produced Cs. melanura in numbers equal or greater than last year. These were also the same locations where mosquitoes infected with EEEV and WNV were obtained. We hope to inspect the vicinity of these sites to determine if beaver impoundments are contributing to the habitat to favor the breeding and development of Cs. melanura. The greatest mosquito-related public-health concern during a season-long drought is the abundance of the principal WNV vectors in the District, Culex pipiens and Cx. restuans. It has been known that these species exhibit often "explosive"population increases during prolonged droughts and excessively warm summers; this phenomenon has been observed in several seasons in the District in the past twelve years. When their populations "skyrocket", collections of WNV-infected mosquitoes also increase, along with the risk of WNV infections to District residents. Also, of great concern in 2012 was the connection between increased populations of Cx.pipiens and Cx. restuans and increased collections of these mosquitoes infected with EEEV. These two species primarily feed off infected birds, which is how these mosquitoes acquire both WNV and EEEV. However, Cx.pipiens in particular can also feed off humans. If an already- infected female mosquito (its only females that seek blood)bites a person, that person will get infected. How sick that person will become depends on his or her age and their immune system's 2013 Best Management Practice Plan:North Andover Page 5 health status. Most infected people with WNV will not exhibit any symptoms; we are still not sure if the same can be said for people infected with EEEV. However,people younger than five years and older than fifty and people whose immune systems have been "challenged" or"compromised" (i.e., not in peak health) are at much greater risk of becoming diseased. Diseased WNV-infected people will exhibit symptoms ranging from a severe fever to neurological ailments manifesting as some form of encephalitis. Although the viruses are different, both operate in the same manner and cause similar symptoms and fatalities. These two species "breed"in stagnant water. The more polluted with organic debris is the water, the more attractive the water is to females. Eggs will be readily laid onto the water's surface and upon hatching, the larvae will find plenty of bacteria to eat in that rank putrid foul organic liquid. The stagnant water may be in found along drying pools and ponds, but also in a variety of water-holding containers, whether natural or artificial. Water-filled artificial containers proven most favorable for breeding these Culex species include: • ignored bird baths, • discarded tires in unkempt backyards, • leaf-clogged rain gutters, • uncovered abandoned swimming pools, • improperly folded tarps and plastic bags, • kiddy swimming pools left exposed right-side up, • forgotten rain barrels, • and larger structures such as catch basins and retention ponds. Often during a long drought,just enough rainfall may occasionally refill containers, but not wash the contents away. Thus the polluted containers are replenished to support further breeding, as was the case in 2011 resulting in both unprecedented populations of these mosquitoes and WNV detections. However, most surprisingly in 2012, the extended drought coupled with higher-than-normal temperatures did NOT result in excessive numbers of these Culex mosquitoes throughout the District! Overall, there was a decrease by over one-third from 2011 numbers!! The occasional rains were mostly sporadic and probably not sufficient to augment breeding and many natural pools that were drying became dry and stayed dried. But these explanations do not account for the dramatic decreases seen almost consistently throughout the District. We feel that these decreases were due in large part to the District's aggressive season-long campaign to treat the catch basins with larvicides ("kill or retard larvae"). Depending on agreements between the District and each individual municipality, the larvicidal agents employed were formulations of either a mosquito hormone analog or bacteria. The hormone is similar to one produced by insects, called juvenile hormone, that in high concentrations keep larvae from maturing into adults. The bacteria used were either the same as those used in our aerial salt marsh application or of a closely related species,B. sphaericus, or both. The operational section of this BMP will discuss the use of these agents in some detail. There were only two municipalities that experienced modest to dramatic increases in container- breeding Culex as well as in WNV detections from 2011. The greatest increase was seen in Revere. No city had as many WNV detections as Revere; during one stretch this summer, WNV was detected every week for nine consecutive weeks! And yet, no city in the District were control operations most implemented (both with larvicides and adulticides) as Revere; only after Labor Day did the Culex populations finally decline. The situation in Revere may be the best demonstration 2013 Best Management Practice Plan:North Andover Page 6 that treating catch basins alone will not regulate Culex populations in a city that provides almost endless breeding opportunities for these species. Also, this scenario reminds us that one can do all in a community to control mosquitoes,but one is at the mercy of the extent of(or lack of) mosquito control in adjacent cities; this may be especially true in communities in proximity to cities like Boston with seemingly endless WNV-infected mosquitoes. Unfortunately, reduced Culex populations District-wide did not result in reduced virus detections in mosquitoes. The numbers of WNV-mosquito detections did decrease from 2011 from 56 to 48 infected pools while the number of pools submitted for testing increased. There were no human infections or fatalities from WNV in the District whereas there was one WNV-infected human in each of the previous two years. On the other hand, EEEV detections in Culex mosquitoes appeared for the first time in the District since 2009 and in greater frequency than reported in 2009. Possible reasons to explain these phenomena will be discussed below. Figure 2. NE MA Mosquito Control District Municipalities reporting WNV and Figure 1. NE MA Mosquito Control District EEEV infections in 2012 Municipalities reporting one or more Legend WNV-infected mosquito pools in 2011. Towns wrath EEEV Hnnrnan Caws. Towns with EEEV Dateclions =Towns wdih B07H EEEV&*NV Towns with VV NV Detections I I Towns not in Jilsvm Toms in while had no vbrws doweted 1 M il J�12.15&dRxW i I r w€uRv ins mdiws.l r a RpUE.'l,: li j w 2 4 � A t , vNi 11 I I� r a ino; .�., aim . vrrui n,Wrkr:rr: , i 1d Ro rcp6 ynrtrc aNen esaEw 411 1 ^, Mol trm ,-NJ 9 i aawt.,re!'v AWlYMF rlR Y,';AIC7 / ... I13TT 7% M,w�Nnk EMkAiS:. ./ 44 N A, IYwvu a r' G i H P bd a ON I Map by A.Corricelh u ' n. n Map by A.Corricelh , w �e t 2013 Best Management Practice Plan:North Andover Page 7 For the remainder of this report, we will focus on the arboviruses. This was the second consecutive season of intense arboviral activity throughout the District. However, whereas in 2011 the virus encountered was only WNV, in 2012 both WNV and EEEV were detected in abundance and distribution (see maps above). The unprecedented District-wide viral activity resulted in extensive larvicidal and adulticidal responses to a degree also unprecedented. Sadly, there were two fatalities caused by EEEV(in Georgetown and Amesbury). There were also two animal fatalities resulting from EEEV, both horses (Georgetown and Essex; Essex is not a subscribing municipality). Although it was suspected that WNV presence was going to be high due to the dry and hot summer experienced, the presence and spread of EEEV in the District was a greater surprise, being that EEEV-vector populations were unusually low and no EEEV was reported in southeastern New Hampshire for most of the summer. Southeast NH had been the focus of EEEV activity in the region north of Boston for almost the past decade. Reasons as to why EEEV appeared in the District are speculated below. 1,038 mosquito samples ("pools") for testing were sent to MA DPH in 2012, surpassing the 1,001 pools sent in 2011. This year's pool submissions were the most the District has ever sent for testing and the most sent by any mosquito control project (MCP)in Massachusetts in 2012. A "pool" consists of anywhere between two to fifty mosquitoes of a single species of mosquito taken from a single location. With regards to our pools: • 60 infected mosquito pools were collected in 2012, whereas 56 infected pools, all WNV- infected, were recovered last year. Of this year's 60 pools, 46 tested positive for WNV, 12 tested positive for EEEV and, in a first for our District, there were two pools that had BOTH viruses detected! • 22 municipalities had one or both viruses detected(as with last year, two-thirds of District municipalities had some virus detected). 15 municipalities had only WNV detected, two municipalities with only EEEV detected, and five municipalities with BOTH viruses collected. Whereas the spread of WNV in the District was comparable to what was observed in 2011, the distribution of EEEV in the District was unprecedented. The municipalities with infected mosquito pools (number of pools in parentheses with red numbers being WNV pools and blue being EEEV pools)include: Amesbury (1), Andover(1), Boxford (1), Groveland(1), Hamilton (f, 3, 1 combined), Haverhill (2, 1), Lynnfield(2), Manchester (2), Merrimac (f), Methuen (4), Nahant(f), Newbury (4,1), Newburyport(f), Peabody (f, 1, 1 combined), Revere (13), Rowley (1), Salisbury (f), Saugus O, Swampscott(f), Topsfield (f, 3), Wenham (2), and Winthrop (4). Towns that for the first time had WNV-positive pools included Groveland and Salisbury; the two WNV-infected pools in Manchester were the first mosquito infections detected in that community since it entered the District in 2008. Towns with first-time EEEV-mosquito pools were Lynnfield, Rowley, Newbury, and Topsfield; Newbury (specifically in Byfield)previously had an alpaca infected with EEEV in 2009. • All of the types of traps deployed, regardless of whether they were permanent or temporary, collected infected mosquitoes. 30 infected pools came from mosquitoes trapped in permanent season-long HTS; 15 infected pools came from temporary gravid traps; eight infected pools came from resting box traps; and seven infected pools came from temporary CDC traps. 2013 Best Management Practice Plan:North Andover Page 8 Again, as seen in 2011, several species of mosquitoes were detected with viruses. The species found infected were: • Culex pipiens/Cx. restuans complex. A species complex is one which two or more species are morphologically identical but biologically distinct(i.e., we just can't tell them apart). This species complex, as stated earlier, is the both the principal bird-to-bird(i.e., "enzootic") and bird- to-human (i.e., "epidemic")vector of WNV in Massachusetts. There were 40 pools of this complex infected with WNV, two pools infected with EEEV, and one pool infected with both viruses. • Culiseta melanura. This species is the usual enzootic vector for EEEV, but since its preferred hosts are birds, this species can pick up WNV from infected birds as well. There were eight pools infected with EEEV, two with WNV, and one with both viruses. • Culex salinarius. This species is suspected to be the "best"vector for WNV. One pool was found infected with WNV (Wenham) and one with EEEV (Lynnfield). • Coquillettidia perturbans. This species is also deemed to be a good vector of WNV and EEEV. One pool was found infected with EEEV (Hamilton). This infection marks the first time that this species has been found in the District infected with an arbovirus. As already stated, there were no reported human cases of WNV infections in our District. However, the numbers of WNV-human infections are known to be much underreported, according to public health experts, such as Dr. Alfred DeMaria(MA state epidemiologist); only the more severe cases draw attention. There were 33 human cases statewide, as of 14 March 2013 (6 cases of WNV fever and 27 cases WNV neuroinvasive diseases, usually some form of meningitis), the most ever reported in the state. Prior to 2012, the most WNV cases reported in Massachusetts were 24 in 2002. Nation- wide, 2012 was the second worst year so far with 5,387 reported human cases and 243 fatalities (as of 11 December 2012). Of increasing concern statewide, as well as nationwide, is the sharp increase in WNV-neuroinvasive infections. The reasons are not yet fully known for this increase; hypotheses range from improved diagnosis to genetic changes in the virus to cause more serious illness (i.e., increasing its "virulence"). Extensive WNV and EEEV activity was not restricted to Essex County. 2012 was an intense arbo- viral season for the state. There were 307 WNV-infected mosquito pools and 267 EEEV mosquito pools statewide with most coming from the eastern half of the state. The Department of Public Health deemed the EEE threat more dangerous to the state's residents with at least eight different species of mosquitoes infected with EEEV. The state authorized two fixed-wing adulticidal air sprays over much of Bristol and Plymouth counties in July and August. The extremely low presence of floodwater mosquitoes in late summer may have been the principal reason why EEEV and WNV were not as prevalent in Essex County as compared to Plymouth and Bristol counties.These mosquitoes,principally Aedes vexans and AL canadensis, are also notor-ious human-biting mosquitoes and can effectively transmit these viruses. Had their populations in Essex County achieved the levels found south of Boston, there would have been more human disease cases here! Nevertheless, the relatively few mosquitoes of the aforementioned Aedes species collected from mid-August onwards were sent to the State Labs to be tested; none were found infected. As summarized earlier in this report, District pre-emptive control operations together with favorable weather conditions in 2012 yielded much fewer mosquitoes overall than observed in 2011. How- ever, more virus-infected mosquitoes were detected in 2012 than 2011, more than any previous year. 2013 Best Management Practice Plan:North Andover Page 9 The disappointing conclusion is that while mosquito populations can be reasonably managed, the viruses they transmit cannot be to the same extent. With regards to virus-infected birds, nothing can be reasonably done to reduce or stop their move- ments into the District. This is how we believe EEEV entered the District in 2012. Due to both low Cs. melanura numbers and probably very little EEEV presence in southeastern New Hampshire, there was no cycling of EEEV in New Hampshire and Essex County for most of 2012. Later in the summer however, EEEV-infected birds migrated from southeastern Massachusetts and congregated at the limited wetlands in Essex County where they were bitten by mosquitoes breeding at these same wetlands. The infected mosquitoes were dispersed and eventually bit local birds which in turn served as sources of virus for new mosquitoes, and the cycle continued throughout the rest of the summer and into more urbanized areas. This hypothesis may also explain why EEEV appeared in New Hampshire after it appeared in Essex County. More EEEV and WNV were detected in the District in the past four years than all the previous years combined. This pattern is also seen statewide in the past ten years. Nationally in 2012, EEEV remained regional (eastern seaboard and upper Midwest), but WNV appeared across the country in mosquitoes and humans in numbers not seen since 2002 and 2003. The cause of the increase in the transmission and amplification of WNV is not known. It is suspected that in many parts of the country, decline in mosquito pre-emptive and responsive control funding and operations may be behind the increase in WNV in so much of the US in 2012. However, as reported earlier, funding for surveillance and control operations was not decreased in our District for 2012. So, what is going on? Changes in climate patterns may be part of the answer and how these changes affect pathogen- vector-host interactions is now slowly becoming understood. Dr. Theodore Andreadis (Connecticut Agricultural Experiment Station)presented, at a recent meeting of the Northeastern Mosquito Control Association, exactly how climate change may be affecting vector species. The effects from increased atmospheric warming include: • extending the season mosquitoes are active; • increasing survival of overwintering adults; • shortening larval developmental time thus allowing adults to mature faster; • increasing the frequency of adult feeding and survival; • extending the distribution range of many/most vector species. The increases in overall ambient summer temperatures, as exhibited this past summer, may allow viruses to complete their"development"in mosquitoes more quickly and more quickly be transmitted by mosquitoes. Increases in precipitation will increase the numbers and quality of larval breeding sites of many vector species and increased humidity will assist in increased overall survivorship of the adults. However, decreases in overall precipitation can be advantageous to other vector species by increasing their breeding sites (natural and containers) during droughts, as normally exemplified by the vectors of West Nile virus. The overall take home message from what has been observed and analyzed during the past two seasons is that with changes in historical patterns of climate, we will continue to see widespread and abundant activity of arboviruses and the mosquitoes that transmit them. Therefore, the risk of human infections from these viruses will persist and possibly increase, as well as the costs to protect and treat the human cases. 2013 Best Management Practice Plan:North Andover Page 10 North Andover As overall mosquito populations decreased District-wide in 2012, they also decreased in North Andover by over 50%, as collected at both trapping stations, the regular HTS at the DPW lot and the gravid trap-only station behind the Senior Center. Most importantly, there was over a 50% decrease in Culex pipiens and Cx. restuans populations from 2011 levels. As reported in the preceding section,populations of these two species dropped overall district-wide and given that conditions that promote high numbers were most prevalent last summer, the reductions in their population could be attributed to the District's aggressive catch basin treatment program. We believe this was the case as well in North Andover. The reduction in numbers of Cx.pipiens and Cx. restuans may also help explain the lack of WNV detections in these mosquitoes last summer. In addition, besides collections of mosquitoes from the HTS, numerous additional temporary trappings were made around the town on many occasions over the summer, and the relatively few mosquitoes collected were not infected. What a change from 2011 and especially 2010! No EEEV was detected in North Andover as well. Nonetheless,North Andover cannot reduce it vigilance or concern being that both these viruses were collected from mosquitoes from all bordering communities. No changes are projected for surveillance in 2013. Focus of Operations The District's Vector Management Plan VMP will take precedence over all operations prescribed in this BMP. Regional control efforts will focus primarily on adult mosquito surveillance, virus testing and preemptive virus intervention strategies. Specific to North Andover, the primary focus of control efforts will be on virus intervention for West Nile and EEE through freshwater larviciding and catch basin treatments. Regional Control Measures Regional Adult Mosquito Surveillance Program: The importance of surveillance data in reducing the risk of vector borne disease can not be overstated. By focusing on areas of heightened viral activity,preemptive control measures can be timely, efficient and effective. In 2002 we expanded and greatly improved our surveillance program by developing and implemented an automated carbon dioxide (CO2) surveillance system. This system incorporates a COz modified light trap and gravid trap into one automated unit. COz traps are used to sample the general adult mosquito population, monitor both short and long term trends, and determine dominant species and population density. Gravid traps are designed to collect adult female Culex species the primary vectors of WNV. One of these dual function units is placed in a fixed location in each member municipality for a total of 32 deployed throughout the District. Mosquitoes are collected and identified from each trap twice a week beginning on or about May 13'h through October 2nd and beyond if conditions and circumstance warrant. To supplement Culex collections from fixed gravid trap locations, the District will deploy additional gravid traps at multiple random location in communities with a history of WNV activity as conditions and circumstances warrant. The District will operate 128 resting boxes at 16 sites. Resting boxes are designed to collecting blood fed female Culiseta melanura mosquitoes relevant to EEE transmission. The District began 2013 Best Management Practice Plan:North Andover Page 11 deployment of resting boxes in 2006 in response to the emergence of EEE in the Northeast and they have proven to be a valuable tool in early intervention. Six to eight resting boxes will placed at each fixed location and there will be two fixed locations in communities bordering New Hampshire as well as other communities considered to be at risk. The District will collect and identify samples from each trap twice a week and the specimens will be tested for virus. In the event Cs. melanura mosquitoes collected from resting box sites test positive for EEE the District will deploy portable COz traps at those sites. Whereas Cs. melanura rarely bites humans they serve as an early indication of the presences of EEE in the environment. COz traps attract human biting mosquitoes and mosquitoes testing positive from COz traps indicated heightened risk. Virus Testing: Specimens from our trap collections will be sent to The Massachusetts Department of Public Health (DPH) to be tested for the presence of encephalitis viruses. Regional Vector/Virus Intervention: Control efforts will focus on early intervention strategies in municipalities that have shown a greater risk to mosquito borne virus based on events of the previous season and surveillance data. This approach is in the best interest of all member municipalities as focused early intervention strategies seem to demonstrate containment of WNV, and may reduce the risk of exposure to humans and the spread of this disease to other municipalities. Control Measures Specific to North Andover Catch Basins: Catch basins, retention ponds, detention basins, etc. will be checked and treated as necessary, not to exceed one day per week from May lst to August 31st Ground Larviciding: Larviciding sites will be treated first in those communities prioritized in the Districts VMP. Sites will be monitored by degree of breeding in relationship to proximity to human populations and evaluated for short term treatment considerations. Mosquito larviciding sites from the District's data base and areas requested by the Board of Health will be checked and treated as necessary, in lieu of catch basin treatments, not to exceed one day per week from April 1st to August 31st and beyond if circumstances warrant and conditions allow. Manual Ditch Maintenance: In the course of catch basin treatments and larviciding, roadside ditches and culverts will be manually cleared of manageable blockages and debris in order to reduce mosquito breeding habitat and or potential habitat. Inspectional Services: While the District is authorized under the provisions of Chapter 252: section 4 of the General Laws of the Commonwealth to enter upon lands for the purpose of inspection, it is not a regulatory agency. Nor is it our intention to impose on any resident or business, but rather to be a resource for information and technology to help property owners prevent or abate mosquitoes to the mutual benefit of the property owner and the community. The District will act as a technical advisor as requested by the Board of Health and represent the municipalities public and animal health and human annoyance concerns relative to mosquito breeding,potential breeding and proposed development. The District, at the request of the Board of Health will also review site plans and inspect sites were storm water structures are planned or under construction. Upon inspection of a site the District will make written recommendations, submit these recommendations to the Board of Health and "cc" a copy to the land owner. 2013 Best Management Practice Plan:North Andover Page 12 Property Inspection: Socioeconomics often plays an important role in mosquito control and associated public health risk. This is evident by a study conducted in 2007 entitled"Delinquent Mortgages, Neglected Swimming Pools, and West Nile Virus, California"which demonstrates a 276%increase in the number of human WNV cases in the summer of 2007 associated with a 300% increase in foreclosures which led to a large number of neglected swimming pools in Bakersfield, Kern County. Last year we received many requests from Boards of Health to inspect abandoned properties. While the district has a long standing policy of property inspections at the request of Boards of health, in the past we have taken a passive approach to property inspection. Given the current economic climate and likelihood of increasing property abandonment and the potential for increased health risk associated with property abandonment the district will take a more aggressive approach to property inspections. In the course of our routine activities in your community we will be on the lookout for such properties and report such properties to Boards of Health. We understand that addressing concerns related to such properties is a matter of time and process. In the long term we will offer any support that may be appropriated to resolve mosquito problems related to such properties and in the short term with the Boards of Health's support we will implement the necessary control measures to mitigate the immediate mosquito problem associated with such properties. Adulticiding: Selective adulticiding will be coordinated through the Board of Health. (BOH 2013) For a faster response to data and recommendations for adulticiding, the decision to spray (adulticide and or barrier) will be made by the Chairman or Health Director with the entire Board to be notified as soon as possible. (Ground adulticiding exemption- for those property owners wishing to exempt their property from direct ground application must notify the Town Clerk in writing each year prior to March 1st in accordance with 333 CMR Section 13.03 Nuisance mosquito adult spraying (adulticiding)requests by residents are to be made to the Health Department with the decision for spraying to be made by the Board of Health Chairman and or Director with input from the Mosquito Control District and the entire Board. (Protocol for the decision to spray to be developed internally.) Barrier Treatment: The District uses a system called Ultra Low Volume (ULV) for ground adulticiding applications. ULV is designed to dispense very small amounts of pesticides over a large area. While this is a cost effective means of reducing mosquito populations on a large scale, it only affects those mosquitoes present at the time of the application and repeated applications are sometimes necessary to sustain the initial reduction in the mosquito population in some areas. To reduce the need for repeated applications and provide more sustained relief from mosquitoes in high public use areas, the District will provide barrier treatments to public use areas such as schools (applications to schools must be incompliance with MGL ch85),playgrounds, athletic fields, etc., at the request of the Board of Health. Wetlands Management: The Town may petition the District to undertake larger scale ditch maintenance projects, wetlands enhancement and restoration projects requiring specialized mechanized equipment and expertise. Petitioned sites will be evaluated and a site specific proposal will be written for acceptable projects. Wetlands management projects may be beyond the scope of any municipality's assessment and may require separate and additional appropriation. Mosquito Habitat Mitigation: The District will represent the Towns mosquito control concerns in an advisory capacity relative to proposed development and where prudent as requested by local health officials. 2013 Best Management Practice Plan:North Andover Page 13 Research and Development: Evaluate the efficacy and efficiency of current control methods. Investigate new methods,procedures and technologies in mosquito control and wetlands management and evaluate their implications for use in North Andover. Education: Present educational displays and programs on mosquito control and related wetlands management programs at the request of health officials, schools or civic organizations. Monitor and update local schools, daycares etc. regarding IPM plans and current child protection requirements. (The Board of Health encourages the Health Director and the Mosquito Control work with the school department to update the School IPM plans annually by March 1s) FY14 Percentage of assessment allocated to control measures as prescribed by individual municipality's Best Management Practice Plan, (BMP) in the Town of North Andover For 2014 the District is asking for a level funded budget. Last year the District received a 5%increase, the first increase since 2004. For FY14 we will try to hold the line even after last season's EEE virus outbreak and the increase of West Nile. Our primary goal is to protect our subscribing communities from virus. We will do all in our power to reduce the mosquito populations thus reducing the virus risk to our residents. We look for your support and understanding and that of all the communities we serve if we are to be successful. Assessment: As estimated by the Massachusetts Department of Revenue, Division of Local Services,in accordance with Chapter 516 of the General Laws of the Commonwealth. The assessment formula is based on a regional concept,which considers square miles and evaluation. The District offers this breakdown as a general guide to how these funds are allocated specific to your community. FY14 Estimated Assessment for the Town of North Andover $ 90,159.00 (FY13 $90,159.00) District Breakdown of Administrative and General Operational Cost State Reclamation and Mosquito Control Board 2.45% $ 2208.89 Administration and Facilities Cost Share 28.8% $ 25,965.79 Balance of assessment allocated to Operational Cost 68.75% $ 61,984.31 Specific Control Measures as Prescribed by BMP General Operational Cost Share Regional Adult Mosquito Surveillance Program Regional Vector/Virus Intervention Catch Basins/Larviciding/Manual Ditch Maintenance Wetlands Management 2013 Best Management Practice Plan:North Andover Page 14 Mosquito Habitat Mitigation Inspectional Services Adulticiding ( Board of Health request—see "Control Measures Specific to N. Andover") Research and Development Education 2013 Best Management Practice Plan:North Andover Page 15