Development of an autodissemination strategy for the deployment of novel control agents targeting the common malaria mosquito, Anopheles quadrimaculatus say (Diptera: Culicidae)

Abstract

BackgroundThe reduced efficacy of current Anopheline mosquito control methods underscores the need to develop new methods of control that exploit unique target sites and/or utilizes novel deployment methods. Autodissemination methodologies using insect growth regulators (IGRs) is growing in interest and has been shown to be effective at controlling Aedes mosquitoes in semi-field and field environments, yet little information exists for Anopheline mosquitoes. Therefore, we tested the hypothesis that female-driven autodissemination of an IGR combined with a new mechanism of action insecticide (Kir channel inhibitor) could be employed to reduce Anopheline populations.MethodologyWe studied the ability of three IGRs to be transferred to the larval habitat during oviposition in laboratory and semi-field environments. Adult mosquitoes were exposed to the chemicals for 4 hours immediately after blood feeding and efficacy was tested using classical methodologies, including adult emergence inhibition and High Performance Liquid Chromatography (HPLC). A complete autodissemination design was tested in a semi-field environment.Principal findingsLarval survivability and adult emergence were significantly reduced in habitats that were visited by novaluron treated adults, but no statistical differences were observed with pyriproxyfen or triflumuron. These data suggested novaluron, but not pyriproxyfen or triflumuron, was horizontally transferred from the adult mosquito to the larval habitat during oviposition. HPLC studies supported the toxicity data and showed that novaluron was present in the majority of larval habitats, suggesting that novaluron can be horizontally transferred by Anopheles quadrimaculatus. Importantly, the combination of novaluron and the Kir channel inhibitor, VU041, was capable of reducing adult and larval populations in semi-field environments.ConclusionsNovaluron can be transferred to the adult at a greater efficacy and/or is not degraded as quickly during the gonotropic cycle when compared to pyriproxyfen or triflumuron. Pending field confirmation, autodissemination approaches with novaluron may be a suitable tool to manage Anopheles populations.

Use of Novaluron-Based Autocidal Gravid Ovitraps to Control Aedes Dengue Vector Mosquitoes in the District of Gampaha, Sri Lanka

“…Even though the exact mode of action is still not clear, its capability to inhibit exoskeleton formation in immature stages of insects has enabled it to be used for a broad range of applications. The Novaluron 10 EC solution dissolves well in water, and therefore, tap water was used to prepare a dilution series for laboratory and field experiments with the objective of minimizing the costs and improving convenience and feasibility for end users [27,28]. However, stock solutions were prepared using distilled water following the WHO guidelines [17].…”

“…The maximum residual limit, established by the Codex Alimentarius Commission in United States, of Novaluron for pone-type fruits was 3 ppm [30]. Previous study conducted on autodissemination strategy of IGR on mosquitoes stated that the limit of detection of Novaluron was 0.5 ppb [28]. Therefore, the experiments were performed in the range of 3.0 ppm to 0.5 ppb in the study.…”

Small-scale field assessment of efficacy of the autodissemination approach against Aedes sp. in an urban area

“…albopictus larvae. Thus, it is likely that most studies use a large amount of pyriproxyfen to increase the impact of autodissemination under semi and field conditions [13–17, 59–60]…”

Autodissemination of pyriproxyfen as a method for controlling the house fly Musca domestica

“…The present studies have expanded the range of insect pests that may be suitable targets for the autodissemination approach, from mosquitoes that breed in containers or small water bodies (Caputo et al 2012;Wang et al 2014;Tuten et al 2016;Unlu et al 2017;Akhoundi et al 2018;Swale et al 2018), to house flies that breed in a variety of substrates such as animal manures and rotting vegetation. Overall, we found that the effectiveness of autodissemination for house fly control was affected by fly population size, the proportion of the population that was treated, manure type and location and delivery method.…”

“…This sounds a like a lot, but total fly density should also be taken into account, because in a situation of high fly densities more flies will visit the autodissemination devices, as was exemplified in the study of Unlu et al (2017) on Aedes albopictus. Further field research is required on this topic, with emphasis on several topic areas: (1) Test the effects of treated flies/ manure volume ratio on control rates, in the field; (2) test the feasibility of autodissemination approach on farms, especially poultry operations; (3) improve baiting systems in order to attract more flies under field conditions; (4) evaluate more formula components, such as electrostatic powders (Baxter et al 2008) or even other IGRs (e.g., Swale et al 2018); (5) test autodissemination approaches (either passive or active) in urban habitats (e.g., garbage dumps and other municipal waste facilities), where autodissemination might be a practical way to apply PPF.…”