Mosquito-Disseminated Pyriproxyfen Yields High Breeding-Site Coverage and Boosts Juvenile Mosquito Mortality at the Neighborhood Scale

Abstract

BackgroundMosquito-borne pathogens pose major public health challenges worldwide. With vaccines or effective drugs still unavailable for most such pathogens, disease prevention heavily relies on vector control. To date, however, mosquito control has proven difficult, with low breeding-site coverage during control campaigns identified as a major drawback. A novel tactic exploits the egg-laying behavior of mosquitoes to have them disseminate tiny particles of a potent larvicide, pyriproxyfen (PPF), from resting to breeding sites, thus improving coverage. This approach has yielded promising results at small spatial scales, but its wider applicability remains unclear.Methodology/Principal FindingsWe conducted a four-month trial within a 20-month study to investigate mosquito-driven dissemination of PPF dust-particles from 100 ‘dissemination stations’ (DSs) deployed in a 7-ha sub-area to surveillance dwellings and sentinel breeding sites (SBSs) distributed over an urban neighborhood of about 50 ha. We assessed the impact of the trial by measuring juvenile mosquito mortality and adult mosquito emergence in each SBS-month. Using data from 1,075 dwelling-months, 2,988 SBS-months, and 29,922 individual mosquitoes, we show that mosquito-disseminated PPF yielded high coverage of dwellings (up to 100%) and SBSs (up to 94.3%). Juvenile mosquito mortality in SBSs (about 4% at baseline) increased by over one order of magnitude during PPF dissemination (about 75%). This led to a >10-fold decrease of adult mosquito emergence from SBSs, from approximately 1,000–3,000 adults/month before to about 100 adults/month during PPF dissemination.Conclusions/SignificanceBy expanding breeding-site coverage and boosting juvenile mosquito mortality, a strategy based on mosquito-disseminated PPF has potential to substantially enhance mosquito control. Sharp declines in adult mosquito emergence can lower vector/host ratios, reducing the risk of disease outbreaks. This approach is a very promising complement to current and novel mosquito control strategies; it will probably be especially relevant for the control of urban disease vectors, such as Aedes and Culex species, that often cause large epidemics.

Targeting a Hidden Enemy: Pyriproxyfen Autodissemination Strategy for the Control of the Container Mosquito Aedes albopictus in Cryptic Habitats

“…Pyriproxyfen dissemination was further confirmed by residue analysis of the sentinel cups, while previous autodissemination field studies have tended to rely on larval bioassay to show pyriproxyfen presence and activity but lacked direct evidence of transfer to sentinel cups [25,27,28]. Although, open and cryptic cups have shown the presence of pyriproxyfen, we found a surprisingly large difference in pyriproxyfen concentration between the 2013 and 2014 samples.…”

Mosquito-Disseminated Insecticide for Citywide Vector Control and Its Potential to Block Arbovirus Epidemics: Entomological Observations and Modeling Results from Amazonian Brazil

“…SBSs were 580-ml dark-brown plastic cups containing 400 ml of tap water; they were retrieved after 5–6 d of operation, and their contents kept in the laboratory as previously described [29]. We then recorded (a) the number of juvenile mosquitoes developing or dying in each SBS and (b) the number of adult mosquitoes emerging from each SBS.…”

“…Working under our supervision, municipal vector control staff deployed 1,000 PPF dissemination stations (DSs) scattered over the entire urban area (Fig 1); all site owners gave oral informed consent. DSs were 2-l plastic cups containing 600–700 ml of tap water and with the inner wall lined with black, Oxford-type polyester cloth dusted with 5 g of PPF 0.5% (SumiLarv 0.5G; Sumitomo Chemical, Tokyo) ground to fine powder (see also [29]). Municipal vector control staff visited DSs fortnightly for maintenance (re-dusting with PPF and refilling with water).…”

“…One such insecticide is pyriproxyfen (PPF), an insect juvenile hormone analogue that kills mosquito juveniles at minute doses and can safely be used even in drinking water [3,27,28]. Mosquito-disseminated PPF has been shown to yield high breeding-site coverage and large reductions of adult mosquito emergence across a tropical neighborhood [29]. One crucial open question is whether mosquito-disseminated PPF can effectively reduce mosquito populations at the spatial scale relevant for vector control and disease prevention—the scale of cities and towns.…”

Dengue, zika e chikungunya - desafios do controle vetorial frente à ocorrência das três arboviroses - parte II

“…Algumas prescindem, em princípio, de controle químico adicional ou alternativo como a Abordagem eco-bio-social, que aposta na forte participação social, educação em saúde, manejo ambiental e articulação intersetorial para eliminação mecânica sistemática de potenciais criadouros (7,10) ; e o uso de compostos naturais com atividades larvicidas, como os óleos vegetais produzidos a partir das cascas de frutas cítricas (10) . Já na experiência com estações dispersoras de larvicidas, realizada em duas cidades do Amazonas, as próprias fêmeas do mosquito carreiam o larvicida para criadouros de difícil acesso, tratando-os quimicamente no momento da ovoposição (10,12) .…”