Field Evaluation of a New Strategy to Control Lutzomyia longipalpis, Based on Simultaneous Application of an Adulticide-Larvicide Mixture

Lutzomyia longipalpis: an update on this sand fly vector

Lutzomyia longipalpis is the most important vector of Leishmania infantum, the etiological agent of visceral leishmaniasis (VL) in the New World. It is a permissive vector susceptible to infection with several Leishmania species. One of the advantages that favors the study of this sand fly is the possibility of colonization in the laboratory. For this reason, several researchers around the world use this species as a model for different subjects including biology, insecticides testing, host-parasite interaction, physiology, genetics, proteomics, molecular biology, and saliva among others. In 2003, we published our first review (Soares & Turco 2003) on this vector covering several aspects of Lu. longipalpis. This current review summarizes what has been published between 2003-2020. During this period, modern approaches were incorporated following the development of more advanced and sensitive techniques to assess this sand fly.

High effectiveness of an adulticide-larvicide formulation for field control of sandflies (Diptera: Psychodidae) in the city of Clorinda, Argentina

In Argentina, Leishmania infantum (syn. L. chagasi) is the etiologic agent of human visceral leishmaniosis (HVL), and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) is the main vector. The objective of this study was to evaluate the effectiveness and residual effect of two commercial insecticide formulations, one with permethrin and pyriproxyfen as active ingredients (Dragon Max®) and the other with only permethrin (Flop®) for the control of sandflies. Both formulations were applied in chicken coops and other surroundings structures of the peridomicile of urban houses in Clorinda, Formosa (Argentina). Entomological monitoring was carried out weekly for 44 weeks after the intervention. The results showed great effectiveness and residual effect up to 21 weeks post-intervention for Dragon Max®. This result could be explained by the excellent larvicidal activity of the Insect Growth Regulator (IGR) pyriproxyfen against the immature forms of phlebotomines and by the delay on the restoration of the natural threshold of the vector population in treated sites.

Establishment of a method for Lutzomyia longipalpis sand fly embryo microinjection: The first step towards potential novel control strategies for leishmaniasis

Leishmaniasis is a vector-borne parasitic disease transmitted by sand flies that affects 1.3 million people across 98 countries, with limited control strategies due to the lack of an available vaccine and the emergence of insecticide resistance.  Novel control strategies that are being explored for mosquito-borne diseases, such as Wolbachia bacterial inhibition of pathogens and genetically modified insects (e.g. using CRISPR-Cas9 editing), rely on the ability to consistently inject embryos of the target species.  Here we present a novel method to obtain and inject preblastoderm sand fly embryos of the genus Lutzomyia (Lu.) longipalpis, the principle vector of zoonotic visceral leishmaniasis in South America. The procedures required to obtain sufficiently young Lu. longipalpis colony embryos are described alongside a microinjection technique that permits rapid injection and minimal handling of small sand fly embryos post-injection. Using a strain of Wolbachia as a ‘marker’ for successful injection, our protocol produced early generation Wolbachia transinfected Lu. longipalpis lines, demonstrating its potential as the first step for use in novel applied strategies for sand fly control.

Establishment of a method for Lutzomyia longipalpis sand fly embryo microinjection: The first step towards potential novel control strategies for leishmaniasis

Leishmaniases is a group of vector-borne parasitic diseases transmitted by sand flies that affects 1.3 million people across 98 countries, with limited control strategies due to the lack of an available vaccine and the emergence of insecticide resistance.  Novel control strategies that are being explored for mosquito-borne diseases, such as  Wolbachia bacterial inhibition of pathogens and genetically modified insects (e.g. using CRISPR-Cas9 editing), rely on the ability to consistently inject eggs of the target species.  Here we present a novel method to obtain and inject preblastoderm sand fly eggs of the genus  Lutzomyia (Lu.) longipalpis, the principle vector of zoonotic visceral leishmaniasis in South America. The procedures required to obtain sufficiently young  Lu. longipalpis colony eggs are described alongside a microinjection technique that permits rapid injection and minimal handling of small sand fly eggs post-injection. Using a strain of  Wolbachia as a ‘marker’ for successful injection, our protocol produced early generation  Wolbachia transinfected  Lu. longipalpis lines, demonstrating its potential as the first step for use in novel applied strategies for sand fly control.