2. Physical and legal accessibility for control purposes

In the current absence of safe and economically sustainable methods to sterilize or kill whole populations of adult mosquitoes, and especially ones that might be deployed on a scale and speed required to impact an epidemic, control over potential breeding and resting sites (PBRP) continues to play a pivotal role in the strategies against Aedes.

proposed in Figure 1 distinguishes societal actors (individuals, communities, government) who can be engaged in and held responsible for Aedes management. This classification, detailed below, enables both the identification of optimal allocation of private and public

Smashicons, Good Ware, Revicon, Zlatko Najdenovski, Nikita Golubev and Freepik from www.flaticon.com).

Figure 1. Strategy of societal organization of interventions against Aedes species based on the physical and legal accessibility of the space where the mosquito can be eliminated. The concentric rings contain: (i) the threat (Aedes mosquitoes), (ii) putative breeding and resting places (PBRP) of Aedes mosquitoes based on ownership accountability and physical accessibility, (iii) intervention that would be needed (clockwise, starting from upper-left: Individual citizens, community involvement, governmental direct action, professional assistance) (icon sources: Icons made by Becris, mynamepong,

Urban Ecology and the Effectiveness of *Aedes* Control http://dx.doi.org/10.5772/intechopen.78688 81

(A) Easily accessible & accountable PBRPs. In areas that are both easily accessed and under accountable stewardship, for example, occupied private dwellings, or public facilities under effective management, we propose that the private individuals within the premises are engaged and mobilized. Plates under potted plants, water tanks, garden fountains, birdbaths, water bowls for pets, laundry tubs, toys, swimming pools, cisterns, ponds, etc. can be directly managed by individuals either by draining out the water or filling with sand to prevent adults laying eggs. Current WHO recommendations [17, 18] already charge private individuals with management of PBRPs within 100 m of their homes, which is likely to capture the majority of Aedes aegypti PBRPs [19, 20], and places of public congregation. However we would suggest this be expanded to all owners of accessible spaces with the active encouragement and support of government agencies (an interesting example is the "domestic trap strategy"; Box 1). Such activities are likely to be regular, for example putting out garbage, or infrequent, for example putting lids on water containers, but are seldom labor intensive, assuming changes in routine

responsibilities in each case, but also defines the most suitable set of strategies:

We suggest tackling this challenge by framing it based on these two variables that are especially relevant to the control of PBRPs: accessibility and accountability. The first relates to how easily breeding sites can be accessed for cleaning and intervention purposes. Although most PBRPs can be readily managed by private citizens (e.g., plant pots, fountains, household refuse and sidewalks), some are physically difficulty to locate or access for control purposes (e.g., roof gutters, cracks in houses or water-containing holes in trees). The second factor relates to how the stewardship of land is distributed between individuals, companies or the state. Even though all PBRPs are, in theory, under some legal responsibility (private residence, public buildings and tended public spaces), neglected public spaces (particularly in developing nations) and areas with uncertain ownership are under de facto diffuse or a non-accountable authority and frequently result in a state of abandonment (e.g. vacant lands, neglected public parks, open sewage).

The interaction between these physical and legal factors yields an actionable categorization of areas for vector control (Figure 1) that goes beyond the traditional system of "domestic, peridomestic and public spaces" [16], which is limited to types of habitat. The framework

point. Any inaccessible nook or cranny, any vacant land or neglected facility permits adult mosquitoes to hide and, in as little water as might accumulate in the lid of a bottle, find ideal breeding places. Aedes mosquitoes take advantage of the heterogeneous urban ecologies through "skip oviposition," laying a few eggs, spread across the largest possible number of sites. It is an especially well suited strategy for urban environments with abundant, but sparse

The control of Aedes mosquitoes is failing in most tropical regions [1–3], and human diseases transmitted by this vector, like dengue, chikungunya, yellow fever and Zika, are among the top public health priorities [4, 5]. The strategies for suppressing mosquito populations below a threshold at which they no longer support viral amplification [6–10] has focused on two strategies [7, 11, 12]: (a) negating larval development opportunities by eliminating breeding places and the sites of immature stages; and (b) killing adults by fumigation with insecticides. More recently biomolecular and biogenetic approaches have also been suggested, although their effectiveness under field conditions are uncertain [13, 14]. Therefore new approaches are

Here we propose that an important strategic aspect that is currently overlooked in Aedes control programs: recognition of the complexity of urban ecologies in terms of land ownership, enforcement and accessibility for control interventions. We suggest that a systematic strategy

In the current absence of safe and economically sustainable methods to sterilize or kill whole populations of adult mosquitoes, and especially ones that might be deployed on a scale and speed required to impact an epidemic, control over potential breeding and resting sites (PBRP)

We suggest tackling this challenge by framing it based on these two variables that are especially relevant to the control of PBRPs: accessibility and accountability. The first relates to how easily breeding sites can be accessed for cleaning and intervention purposes. Although most PBRPs can be readily managed by private citizens (e.g., plant pots, fountains, household refuse and sidewalks), some are physically difficulty to locate or access for control purposes (e.g., roof gutters, cracks in houses or water-containing holes in trees). The second factor relates to how the stewardship of land is distributed between individuals, companies or the state. Even though all PBRPs are, in theory, under some legal responsibility (private residence, public buildings and tended public spaces), neglected public spaces (particularly in developing nations) and areas with uncertain ownership are under de facto diffuse or a non-accountable authority and frequently result in a state of abandonment (e.g. vacant lands, neglected public

The interaction between these physical and legal factors yields an actionable categorization of areas for vector control (Figure 1) that goes beyond the traditional system of "domestic, peridomestic and public spaces" [16], which is limited to types of habitat. The framework

that accounts for this physical complexity is essential to best implement Aedes control.

2. Physical and legal accessibility for control purposes

continues to play a pivotal role in the strategies against Aedes.

parks, open sewage).

and even temporary breeding sites [1].

80 Dengue Fever - a Resilient Threat in the Face of Innovation

urgently needed, especially in urban landscapes [15].

Figure 1. Strategy of societal organization of interventions against Aedes species based on the physical and legal accessibility of the space where the mosquito can be eliminated. The concentric rings contain: (i) the threat (Aedes mosquitoes), (ii) putative breeding and resting places (PBRP) of Aedes mosquitoes based on ownership accountability and physical accessibility, (iii) intervention that would be needed (clockwise, starting from upper-left: Individual citizens, community involvement, governmental direct action, professional assistance) (icon sources: Icons made by Becris, mynamepong, Smashicons, Good Ware, Revicon, Zlatko Najdenovski, Nikita Golubev and Freepik from www.flaticon.com).

proposed in Figure 1 distinguishes societal actors (individuals, communities, government) who can be engaged in and held responsible for Aedes management. This classification, detailed below, enables both the identification of optimal allocation of private and public responsibilities in each case, but also defines the most suitable set of strategies:

(A) Easily accessible & accountable PBRPs. In areas that are both easily accessed and under accountable stewardship, for example, occupied private dwellings, or public facilities under effective management, we propose that the private individuals within the premises are engaged and mobilized. Plates under potted plants, water tanks, garden fountains, birdbaths, water bowls for pets, laundry tubs, toys, swimming pools, cisterns, ponds, etc. can be directly managed by individuals either by draining out the water or filling with sand to prevent adults laying eggs. Current WHO recommendations [17, 18] already charge private individuals with management of PBRPs within 100 m of their homes, which is likely to capture the majority of Aedes aegypti PBRPs [19, 20], and places of public congregation. However we would suggest this be expanded to all owners of accessible spaces with the active encouragement and support of government agencies (an interesting example is the "domestic trap strategy"; Box 1). Such activities are likely to be regular, for example putting out garbage, or infrequent, for example putting lids on water containers, but are seldom labor intensive, assuming changes in routine behavior. Ironically, some urban areas may be more accountable to individuals than municipal authorities as facilities (such as piped water or sewerage) fail to keep pace with urban spread [21, 22].

could create a collective drive and a positive sense of societal engagement–a study of community-based Aedes control showed, the most prominent benefit was the satisfac-

Urban Ecology and the Effectiveness of *Aedes* Control http://dx.doi.org/10.5772/intechopen.78688 83

(B) Difficult to access, but accountable PBRP sites. Despite the best efforts of conscientious individuals, it can be difficult to eliminate all breeding places that can be hidden in corners of the urban landscape such as building cracks, roof gutters, crevices in the high trees canopy and slabs [1]. Both private and public agents who find such situations should be encouraged to request professional assistance. Legislation can also be used to improve building practices to

Figure 2. The mosquitérica, a simple larval trap that can be fashioned from common household products (reproduced

and translated with permission from UOL, Brazil).

tion created by 'working together' [27].

## BOX 1. Domestic traps: Crowdsourcing Aedes elimination.

Controlling domestic pests like cockroaches, fleas, flies or ants depends on denying them basic resources (e.g., exposed food and breeding places). However, more radical measures are often needed, and traps are a popular choice, not only due to their effectiveness, but also because they (as opposed to chemical sprays) present less danger to humans and pets. The use of mosquito traps domestically is, however, not simple. For example, blood-feeding traps are not practical, as they can hardly compete with mosquitoes' attraction towards human bodies. Similarly, nectar-feeding based traps have no specificity, and would kill many insects (including bees and butterflies). Breeding traps, although potentially effective, are perceived as dangerous if not well implemented or supervised could promote the multiplication of mosquitoes.

Domestic breeding traps that eliminate the aquatic stages of mosquitoes hold great potential if their hazardous implementation can be eliminated. One way to attempt to bias oviposition to more manageable sites is the use of domestic traps that can be readily managed through regular reminders, once a week, for volunteer households and public facility managers who are charged with cleaning out the water in containers functioning as PBRPs [23–25].

The domestic trap strategy (which would be greatly beneficial to the Mosquito Drain; Box 2) is gaining impetus with the invention of an ingenious house-made trap made with widely available and affordable components (Figure 2, an empty PET bottle, adhesive tape and few square centimeters of mesh fabric source). When the eggs hatch in the cone, the larvae migrate to the bottom of the trap through the mesh, but this same mesh prevents adult mosquitoes from leaving the trap. The "mosquitérica," as it is known, presents several advantages over other domestic trap methods. First, it eliminates the concern about occasional negligence in the periodic need to cleaning up and/or adding larvicide to breeding traps. Second, it is unlikely that mosquitoes would develop resistance to this sort of trap –as opposed to chemical spray or even traps that use larvicide (as in the latter case mosquitoes could avoid surfaces or breeding places based on the odors of those substances). And third, it has been shown that egg-laying females are most attracted to sites containing other immature Ae. aegypti [9] – something this trap offers, since only the hatching adults are killed (by entrapment). Instructions for building such traps went viral in social networks, and it is having wide acceptance among the population.

This crowdsourcing method of mosquito elimination could be promoted by governments through, for instance, calls for co-ordinated action on a fixed date (e.g. mosquito eradication day [26]). Setting a weekly reminder during the epidemic season would be epidemiologically sound, as it is more frequent than the time of larval development (approximately 8–10 days), hence ideal for cleaning plant pots, water fountains, etc. Concerted action propelled by an official reminder (mainly in TV and social media) could create a collective drive and a positive sense of societal engagement–a study of community-based Aedes control showed, the most prominent benefit was the satisfaction created by 'working together' [27].

behavior. Ironically, some urban areas may be more accountable to individuals than municipal authorities as facilities (such as piped water or sewerage) fail to keep pace with urban spread

Controlling domestic pests like cockroaches, fleas, flies or ants depends on denying them basic resources (e.g., exposed food and breeding places). However, more radical measures are often needed, and traps are a popular choice, not only due to their effectiveness, but also because they (as opposed to chemical sprays) present less danger to humans and pets. The use of mosquito traps domestically is, however, not simple. For example, blood-feeding traps are not practical, as they can hardly compete with mosquitoes' attraction towards human bodies. Similarly, nectar-feeding based traps have no specificity, and would kill many insects (including bees and butterflies). Breeding traps, although potentially effective, are perceived as dangerous if not well implemented or

Domestic breeding traps that eliminate the aquatic stages of mosquitoes hold great potential if their hazardous implementation can be eliminated. One way to attempt to bias oviposition to more manageable sites is the use of domestic traps that can be readily managed through regular reminders, once a week, for volunteer households and public facility managers who are charged with cleaning out the water in containers functioning

The domestic trap strategy (which would be greatly beneficial to the Mosquito Drain; Box 2) is gaining impetus with the invention of an ingenious house-made trap made with widely available and affordable components (Figure 2, an empty PET bottle, adhesive tape and few square centimeters of mesh fabric source). When the eggs hatch in the cone, the larvae migrate to the bottom of the trap through the mesh, but this same mesh prevents adult mosquitoes from leaving the trap. The "mosquitérica," as it is known, presents several advantages over other domestic trap methods. First, it eliminates the concern about occasional negligence in the periodic need to cleaning up and/or adding larvicide to breeding traps. Second, it is unlikely that mosquitoes would develop resistance to this sort of trap –as opposed to chemical spray or even traps that use larvicide (as in the latter case mosquitoes could avoid surfaces or breeding places based on the odors of those substances). And third, it has been shown that egg-laying females are most attracted to sites containing other immature Ae. aegypti [9] – something this trap offers, since only the hatching adults are killed (by entrapment). Instructions for building such traps went viral in social networks,

This crowdsourcing method of mosquito elimination could be promoted by governments through, for instance, calls for co-ordinated action on a fixed date (e.g. mosquito eradication day [26]). Setting a weekly reminder during the epidemic season would be epidemiologically sound, as it is more frequent than the time of larval development (approximately 8–10 days), hence ideal for cleaning plant pots, water fountains, etc. Concerted action propelled by an official reminder (mainly in TV and social media)

BOX 1. Domestic traps: Crowdsourcing Aedes elimination.

82 Dengue Fever - a Resilient Threat in the Face of Innovation

supervised could promote the multiplication of mosquitoes.

and it is having wide acceptance among the population.

[21, 22].

as PBRPs [23–25].

(B) Difficult to access, but accountable PBRP sites. Despite the best efforts of conscientious individuals, it can be difficult to eliminate all breeding places that can be hidden in corners of the urban landscape such as building cracks, roof gutters, crevices in the high trees canopy and slabs [1]. Both private and public agents who find such situations should be encouraged to request professional assistance. Legislation can also be used to improve building practices to

Figure 2. The mosquitérica, a simple larval trap that can be fashioned from common household products (reproduced and translated with permission from UOL, Brazil).

reduce PBRPs with difficult access [28], for example, encouraging architects to eliminate open gutters that are hard to access [29]. However, the inevitable existence of those PBRPs almost ubiquitously demand interventions that are applied in a "diffuse way", such as "peri-focal" interventions with residual insecticides [1], release of sterile adult mosquitoes or strategies involving multiple traps ("Mosquito Drain"; Box 2).

(C) Accessible, but non-accountable PBRP sites. Neglected public spaces with rubble, trash (tires, cups, cans, plastic bags and discarded containers) and facilities in neglected public spaces and vacant lands or empty lots are accessible to individuals without special knowledge or expertise. Volunteers from the neighborhood (e.g. coordinated by the community), could engaged, and perhaps incentivized, by government or emerging from social media networks in clean-up campaigns where, periodically, debris is removed, trash cleaned, ditches on the ground sealed, and other sensible interventions that destroy and negate breeding sites for Aedes performed. A survey in Singapore found that vacant properties and construction sites (the latter more appropriately belonging to accountable sites) had a four to seven times higher premises index than landed premises (which were three and a half times higher than apart-

Urban Ecology and the Effectiveness of *Aedes* Control http://dx.doi.org/10.5772/intechopen.78688 85

(D) Difficult to access and non-accountable sites. A comprehensive strategy that accounts for the whole gamut of access for mosquito control measures cannot ignore that there are patches where the capability of the government to influence behavior, enforce the law, or simply access places can provide major challenges - for example due to violent conflict. In those circumstances, top-down interventions (fogging, aerial fumigation, biological control and release of biologically modified Aedes males [7, 11, 36]) may be the only strategies that can promote vector control. We need to be caution about these approaches though, as these specialized and expensive activities offer diffuse control efforts that target adult mosquitoes rather than destroy PBRPs have a long history of use, but little recent evidence for effectiveness in reducing disease burden [37]. Restricting their use to epidemics is recommended because of cost and

Mosquito control depends on human actions, yet those actions are often at the mercy of legal and physical constraints. Dissecting the legal and physical complexity of contemporary urban ecosystems results in a categorization that can assist the effective implementation of interventions. These categories – based on the diversity of putative oviposition and resting sites – can be easily integrated into existing habitat management behaviors, and can be readily integrated into GIS mapping technologies to generate actionable information to tackle endemic infesta-

One principle reason for successful control in the past century was the implementation of aggressive top-down measures [8, 12, 39]. The erosion of governmental capabilities to interfere with individual liberties does not necessarily impede mosquito control, as that "loss" may be compensated by an increasingly technologically-savvy, knowledge-avid and social media linked population can be mobilized to combat mosquito populations [40–42]. The proposed framework assumes that it is possible to effectively engage the local population [7], not only by suppressing areas of infection where they can easily act (e.g. their properties), but also by collaborating in a forcing a "Mosquito Drain" (Box 2) to reach beyond their immediate domain

ments) [19, 35].

environmental impact [17].

tions and unfolding outbreaks [29, 38].

of direct impact.

3. A comprehensive approach for engaging society

## Box 2. Mosquito drain.

The Mosquito Drain is based on the idea of attracting females to ubiquitous oviposition places where larvae can be eliminated (e.g. domestic breeding traps, see Box 1) rather than natural, but inaccessible sites thereby eliminating the next generation of mosquitoes.

In an urban environment, some breeding and resting sites are likely to be inaccessible for cleaning and control (e.g., roofs, crevices, tree holes, etc.; Figure 1). However, not all potential breeding places are equally attractive to laying mosquitoes and "compete" for females' preference. Removal of accessible breeding sites would have the following effects on female mosquitoes in search for oviposition sites:


Because "egg-laying females were most attracted to sites containing other immature Aedes, rather than to sites containing the most food" [9], home traps could become especially attractive to gravid females, and therefore be disproportionally important in reducing the mosquito population. Alternatively, attractants can be added to encourage mosquitoes to preferentially use lethal ovitraps that can be managed or left to biodegrade rather than inaccessible natural PBRPs [32–34]. The Mosquito Drain posits that it is not necessary to eliminate all breeding sites to cause the population to crash, which would not be practicable anyway, but that by (i) removing manageable breeding sites (e.g. putting lids on water containers), (ii) providing alternative attractive breeding sites that are easily managed (e.g. 'lure' breeding adults with a suitable trap) and that (iii) kill future generations of mosquitoes (e.g. adding larvicide to ovitraps) would eliminate sufficient reproductive capability of the mosquito population as to drive the population to extinction or at least pushing the biting population below levels at which virus circulation is sustained.

This is a societal effort that depends on collaboration between (many) individuals and government agencies: individuals would be in charge of eliminating any larvae, pupae and/or eggs that could have been accumulated in domestic breeding places (like plant pots and fountains) whilst governments should broadcast a reminder and coordinate that effort. Government agencies would then be freed to tackle hard to access and public spaces.

(C) Accessible, but non-accountable PBRP sites. Neglected public spaces with rubble, trash (tires, cups, cans, plastic bags and discarded containers) and facilities in neglected public spaces and vacant lands or empty lots are accessible to individuals without special knowledge or expertise. Volunteers from the neighborhood (e.g. coordinated by the community), could engaged, and perhaps incentivized, by government or emerging from social media networks in clean-up campaigns where, periodically, debris is removed, trash cleaned, ditches on the ground sealed, and other sensible interventions that destroy and negate breeding sites for Aedes performed. A survey in Singapore found that vacant properties and construction sites (the latter more appropriately belonging to accountable sites) had a four to seven times higher premises index than landed premises (which were three and a half times higher than apartments) [19, 35].

(D) Difficult to access and non-accountable sites. A comprehensive strategy that accounts for the whole gamut of access for mosquito control measures cannot ignore that there are patches where the capability of the government to influence behavior, enforce the law, or simply access places can provide major challenges - for example due to violent conflict. In those circumstances, top-down interventions (fogging, aerial fumigation, biological control and release of biologically modified Aedes males [7, 11, 36]) may be the only strategies that can promote vector control. We need to be caution about these approaches though, as these specialized and expensive activities offer diffuse control efforts that target adult mosquitoes rather than destroy PBRPs have a long history of use, but little recent evidence for effectiveness in reducing disease burden [37]. Restricting their use to epidemics is recommended because of cost and environmental impact [17].
