Chemical control and insecticide resistance status of sand fly vectors worldwide

Authors: BALASKA, SOFIA - UNIVERSITY OF GREECE - CRETE; FOTAKIS, EMMANOUIL - UNIVERSITY OF ATHENS; CHASKOPOULOU, ALEXANDRA - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); VONTAS, JOHN - UNIVERSITY OF ATHENS

Submitted to: PLOS Neglected Tropical Diseases
Publication Type: Review Article
Publication Acceptance Date: 6/6/2021
Publication Date: 8/12/2021
Citation: Balaska, S., Fotakis, E., Chaskopoulou, A., Vontas, J. 2021. Chemical control and insecticide resistance status of sand fly vectors worldwide. PLOS Neglected Tropical Diseases. 15(8): e0009586. https://doi.org/10.1371/journal.pntd.0009586.
DOI: https://doi.org/10.1371/journal.pntd.0009586

Interpretive Summary: Phlebotomine sand flies, mainly aggregated in the tropics and subtropics, are prominent vectors Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. Sand fly insecticide-based control is one of the main strategies used for defense against leishmaniasis. Nevertheless, the reliance on insecticides for controlling leishmaniasis and/or other co-endemic vector-borne diseases (e.g. malaria), as well as additional pressure from agricultural insecticidal interventions, has triggered the development of insecticide resistance in key sand fly vector species’ populations. Here, we review the current methods and active ingredients applied for sand fly chemical control, as well as the insecticide resistance data available for key sand fly vector species worldwide. Future perspectives for improving the efficiency and sustainability of sand fly control applications, in the Genomics Era, including the use of molecular diagnostics for evidence- based insecticide resistance management and the introduction of alternative biotechnology- based approaches are discussed.

Technical Abstract: Phlebotomine sand flies are prominent vectors of Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly chemical- based vector control is a key component of leishmaniasis control efforts. We performed a literature review on the current interventions, primarily, insecticide-based used for sand fly control, as well as the global insecticide resistance (IR) status of the main sand fly vector species. Indoor insecticidal interventions, such as residual spraying and treated-bed nets are most widely deployed, while several alternative control strategies are also used in certain settings and/or are under evaluation. IR has been sporadically detected in sand flies in India and other regions, using non standardized diagnostic bioassays. Molecular studies are limited to monitoring of known pyrethroid resistance mutations (kdr) which are present at high frequencies in certain regions. As the leishmaniasis burden remains a major problem at a global scale, evidence- based rational use of insecticide- centred interventions is required to meet public health demands. Standardized bioassays and molecular markers are a prerequisite for this task, albeit are lagging behind. Experiences from other disease vectors underscore the need for the implementation of appropriate IR Management (IRM) programs, in the framework of Integrated Vector Management (IVM). The implementation of alternative strategies seems context- and case- specific, with key eco-epidemiological parameters yet to be investigated. New biotechnology- based control approaches might also come into play in the near future to further reinforce sand fly/leishmaniasis control efforts.