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

Abstract

BackgroundThe Asian tiger mosquito, Aedes albopictus, is a vector of dengue, Chikungunya, and Zika viruses. This mosquito inhabits a wide range of artificial water-holding containers in urban and suburban areas making it difficult to control. We tested the hypothesis that female-driven autodissemination of an insect growth regulator could penetrate cryptic oviposition habitats difficult to treat with conventional insecticidal sprays.MethodologyOviposition preferences of Ae. albopictus females for open and cryptic cups were tested in semi-field experiments. Two conventional larvicidal sprayers were tested to determine droplet penetration and larvicidal efficacy in open and cryptic habitats using Bacillus thuringiensis var. israelensis (Bti) in the field. Finally, the efficacy of pyriproxyfen autodissemination stations was assessed in cryptic and open cups in residential areas during 2013 and 2014.Principal FindingsGravid females strongly preferred cryptic (53.1±12.9 eggs/cup) over open (10.3±4.3 eggs/cup) cups for oviposition. Cryptic cups showed limited droplet penetration and produced 0.1–0.3% larval mortality with a conventional backpack and low-volume sprays of Bti. The autodissemination stations effectively contaminated these cryptic cups (59.3–84.6%) and produced 29.7–40.8% pupal mortality during 2013–2014. Significant pupal mortality was also observed in open cups.ConclusionsThe autodissemination station effectively exploits the oviposition behavior of wild gravid females to deliver pyriproxyfen to targeted oviposition habitats. Although the pupal mortality in cryptic cups was relatively lower than expected for the effective vector control. Autodissemination approach may be a suitable supporting tool to manage Ae. albopictus immatures in the cryptic habitats those are less accessible to conventional larvicidal sprays.

Using UPLC–MS/MS to Evaluate the Dissemination of Pyriproxyfen by Aedes Mosquitoes to Combat Cryptic Larval Habitats after Source Reduction in Kaohsiung in Southern Taiwan

“…aegypti in our study. This result was similar to those of Unlu et al [19] and Chandel et al [20], in which the PPF residual in water samples taken from sentinel cups ranged from 4 to 11 ng/L, causing more than 70% pupal mortality in Ae. albopictus.…”

“…The concentration of PPF product used in our study (0.01%) was relatively low compared to that in other studies, and the result showed that the mean EI% was 37% one month post-spraying. This EI% observed in our field trial was similar to the value from a study by Chandel et al, in which the mean percentage of pupal mortality was 29.7% among cryptic sentinel cups [20]. Although the low concentration of PPF used in the field may have a weak EI effect, it would rarely harm untargeted creatures, making it an ecofriendly strategy to control mosquitoes.…”

“…First, previous studies measured outcomes solely by observing EI in immature mosquitoes but lacked direct evidence of the existence of PPF in breeding water. Only a few studies measured the attachment and retention of PPF on Aedes mosquitoes [18], and the PPF residual in the water from sentinel cups was measured using LC-MS/MS [19,20]. This study developed a UPLC-MS/MS analytical method for detecting and quantifying PPF in breeding water and further explored the dose-response effect on immature Ae.…”

Truck‐mounted area‐wide applications of larvicides and adulticides for extended suppression of adult Aedes albopictus

“…The combination of larviciding and adulticiding at half the label rate was followed by a second adulticiding also at half the label rate within 2–4 days, depending on weather conditions, using truck‐mounted ULV sprays . The purpose of this additional adulticiding campaign was to increase the efficacy of intervention efforts by targeting the adults that emerged because the larvae were already late fourth instar or pupae at the time of the intial larviciding event . We repeated pyriproxifen larviciding and pyrethroid adulticiding on 16 September 2011 when the mean number of Ae .…”

“…37 The purpose of this additional adulticiding campaign was to increase the efficacy of intervention efforts by targeting the adults that emerged because the larvae were already late fourth instar or pupae at the time of the intial larviciding event. 38,39 We repeated pyriproxifen larviciding and pyrethroid adulticiding on 16 September 2011 when the mean number of Ae. albopictus was five or more (males and females), which was a pre-set intervention threshold for this study.…”