BackgroundIndoor residual spraying is key to dengue control in Cairns and other parts of northern Queensland, Australia, where Aedes aegypti is prevalent, but the strategy faces challenges with regards to slow application time and, therefore, community coverage. A faster potential improvement might be the use of polyethylene netting impregnated with the volatile pyrethroid metofluthrin (SumiOne™). This formulation was assessed in rooms in three houses in Cairns, Australia. One emanator was placed in each room and cages of 10 female Aedes aegypti were exposed at distances of 1 and 3 m. Knockdown and landings on a human hand were counted before metofluthrin exposure and at 10, 30, 60, 90 and 120 min during exposure. In addition, two trials continued over 48 h of exposure to assess the long-term sublethal effects of metofluthrin on caged mosquitoes.ResultsPercentage landing rates fell to 0–2.5% in the first 10 min of exposure. Knockdown was most evident between 10 and 30 min (54% at 1 m and 33% at 3 m). Distance from the emanator strongly affected the results: mosquitoes at 3 m exhibited less knockdown and more landings than those at 1 m. As room volume increased, knockdown decreased and the number of landing increased. There is a cumulative mortality and landing inhibition and, for mosquitoes exposed to metofluthrin for > 48 h, mortality was 100% at 1 m and 90% at 3 m. Of those still alive, a small number continued to land and bite. After being removed from metofluthrin-treated rooms, exposed insect cages were found to reducing landing rates for up to 2 h.ConclusionsDespite only moderate levels of knockdown during the initial hours of exposure, metofluthrin emanators were effective in reducing mosquito landing rates, especially within 1 m, even when exposed on an open veranda. The evaluation methods and results described in this paper will help inform the optimal conditions of deployment of metofluthrin emanators. These devices have the potential to reduce contact between humans and urban disease vectors faster than indoor residual spraying so supplement our current arsenal of dengue control tools.

The residual efficacy of lambda-cyhalothrin sprayed on foliage was evaluated against various mosquito species in sections of forest in Cairns, Queensland, Australia Weekly sweep-net collections in treated and untreated areas before and after spraying showed 87-100% reductions in mosquito numbers for the first 9 wk postspray. After that period, reductions fluctuated but remained >71% up to 14 wk posttreatment. Mosquito mortality ranged from 96 to 100% in contact bioassays of treated leaves during the 14 wk study. Our results demonstrate that spraying harborage vegetation with lambda-cyhalothrin is an extremely effective strategy for the control of sylvan and peridomestic mosquito species in tropical north Queensland.

Background Yellow fever, dengue, chikungunya and Zika viruses are responsible for considerable morbidity and mortality in humans. Aedes aegypti and Aedes albopictus are the most important mosquito vectors involved in their transmission. Accurate identification of these species is essential for the implementation of control programs to limit arbovirus transmission, during suspected detections at ports of first entry, to delimit incursions or during presence/absence surveillance programs in regions vulnerable to invasion. We developed and evaluated simple and rapid colorimetric isothermal tests to detect these two mosquito species based on loop-mediated isothermal amplification (LAMP) targeting the ribosomal RNA internal transcribed spacer 1 (ITS1). Methodology/Principal findings Samples were prepared by homogenizing and heating at 99 o C for 10 min before an aliquot was added to the LAMP reaction. After 40 min incubation at 65 o C, a colour change indicated a positive result. The tests were 100% sensitive and species-specific, and demonstrated a limit of detection comparable with PCR-based detection (TaqMan chemistry). The LAMP assays were able to detect target species for various life stages tested (adult, 1 st instar larva, 4 th instar larva and pupa), and body components, such as legs, wings and pupal exuviae. Importantly, the LAMP assays could detect Ae. aegypti DNA in mosquitoes stored in Biogents Sentinel traps deployed in the field for 14 d. A single 1 st instar Ae. aegypti larva could also be detected in a pool of 1,000 non-target 1 st instar Aedes notoscriptus, thus expediting processing of ovitrap collections obtained during presence/absence surveys. A simple syringe-sponge protocol facilitated the concentration and collection of larvae from the ovitrap water post-hatch.