Crouching Tiger, Hidden Trouble: Urban Sources of Aedes albopictus (Diptera: Culicidae) Refractory to Source-Reduction

Abstract

Our ultimate objective is to design cost-effective control strategies for Aedes albopictus, the Asian tiger mosquito, an important urban nuisance and disease vector that expanded worldwide during the last 40 years. We conducted mosquito larval surveys from May through October 2009 in the City of Trenton, New Jersey, USA, while performing intensive monthly source-reduction campaigns that involved removing, emptying, or treating all accessible containers with larvicides and pupicides. We examined patterns of occurrence of Ae. albopictus and Culex pipiens, another urban mosquito, among different container types by comparing observed and expected number of positive containers of each type. Expected use was based on the relative frequency of each container type in the environment. Aedes albopictus larvae and pupae were found significantly more often than expected in medium volumes of water in buckets and plant saucers but were rarely collected in small volumes of water found in trash items such as discarded cups and cans. They were also absent from large volumes of water such as in abandoned swimming pools and catch basins, although we consistently collected Cx. pipiens from those habitats. The frequency of Ae. albopictus in tires indicated rapid and extensive use of these ubiquitous urban containers. Standard larval-based indices did not correlate with adult catches in BG-Sentinel traps, but when based only on Ae. albopictus key containers (buckets, plant saucers, equipment with pockets of water, and tires) they did. Although we found that only 1.2% of the 20,039 water-holding containers examined contained immature Ae. albopictus (5.3% if only key containers were counted), adult populations were still above nuisance action thresholds six times during the 2009 mosquito season. We conclude that in urban New Jersey, effective source reduction for Ae. albopictus control will require scrupulous and repeated cleaning or treatment of everyday use containers and extensive homeowner collaboration.

The State of the Art of Lethal Oviposition Trap-Based Mass Interventions for Arboviral Control

“…A standard approach in pest control is to exploit “weak links”, critical needs of the pest that may be targeted for control [13], such as the characteristic behavior of urban Aedes females to lay eggs in artificial (man-made) water-holding containers [14,15,16]. Of note, in temperate regions, where with some exceptions [17,18] Aedes -vectored viruses are still a worry and not a panic, public health campaigns employ residents to empty or remove any water-holding containers from their yards [19].…”

“…A larger trap, besides holding more attractive infusion [39], allows for longer maintenance intervals and also provides a more conspicuous visual target for gravid females searching for suitable oviposition sites by a greater release of infusion and olfactory attraction. When dealing with females that “skip-oviposit” and the almost impossible task of removing all other sources of standing water where a female may choose to lay eggs [14,16], it makes sense to stack the odds towards deploying the most attractive lethal oviposition trap and kill the ovipositing females at their first try. While urban Aedes will enter small openings to gain access to water in hard-to-find (cryptic) areas [26,40], they typically will first lay eggs in open containers of easy access, if those are present [26].…”

Photoperiodic Diapause and the Establishment ofAedes albopictus(Diptera: Culicidae) in North America

“…albopictus has become one of the most abundant container-breeding mosquitoes in many suburban and urban areas of eastern North America (Farajollahi and Nelder 2009, Dowling et al 2013, Unlu et al 2013. Aedes albopictus is a significant biting pest (Halasa et al 2012, Unlu et al 2013, and local infestations can impact human behaviors such as time spent on outdoor activities (Worobey et al 2013, Halasa et al 2014. Furthermore, this aggressive human-biting mosquito is capable of transmitting at least 22 arboviruses, including dengue (DENV) and chikungunya (CHIKV) viruses (Gratz 2004).…”

Mosquito (Diptera: Culicidae) Habitat Surveillance by Android Mobile Devices in Guangzhou, China

“…Urban sources of Aedes albopictus are usually refractory to source-reduction in New Jersey, USA [15], however, the source reduction impacted the spatial distribution and abundance of the immature mosquitoes [6,11]. Based on our survey results, the source reduction effort should focus on small containers in Guangzhou City.…”