A Comparison of Hay and Fish Emulsion-Infused Water as Oviposition Attractants for the CDC Gravid Trap

Xenomonitoring as an epidemiological tool supporting post-stop surveillance of albendazole-ivermectin mass drug distribution in the Bougouni-Yanfolila evaluation unit, Sikasso, Mali, in 2023

INTRODUCTION

Mali and Guinea share a border and are both endemic for lymphatic filariasis (LF). However, their progress towards eliminating this disease varies. Mali is currently in the LF transmission assessment survey phase (TAS), while Guinea continues to implement mass drug administration (MDA). As the populations of these two countries are closely related, and vectors are present, the emergence of LF is theoretically possible in the Bougouni-Yanfolila evaluation unit (EU). This XenoFil study, which combines xenomonitoring and serosurveillance in health facilities, was used as a surveillance tool to assess LF transmission. The aim is to detect the emergence of LF in cross-border areas within the Bougouni-Yanfolila EU, after the third LF transmission assessment survey (TAS3).

METHOD

In the Bougouni-Yanfolila EU, we conducted a cross-sectional study to collect mosquitoes in the villages and blood samples from 6 years old and above (≥ 6 years old). In June, August 2022, and January 2023, we conducted three entomological studies in two ecologically distinct villages. The Ifakara type C tent trap (IFAKARA), the gravid trap, and indoor Pyrethrum spray catches were used to collect mosquitoes. For qPCR, mosquito of the same species was sorted into pools of twenty for molecular analysis using qPCR. The infection rate / the parasite prevalence was generated by the PoolScreen® 2 software. Trained local health workers performed serological surveys using filariasis test strips.

RESULTS

In. the two study villages, we collected a total of 4,732 mosquitoes, of which 989 belonged to the species Anopheles gambiae s.l. and 3,743 to species of the genus Culex sp. A total of 264 pools were formed, with the genus Culex spp. accounted for 79.92% (211/264), while the genus Anopheles represented 20.08% (53/264). In June 2022, only one pool (0.53%) of Culex spp. tested positive [95% CI: 0.01-2.89]. Positive Anopheles pools were absent. The blood of ten of the 2056 individuals had positive results [0.49% (10/2056)]. Among the positives, one belonged to 6-7 years, two to that of 8-17 years, and seven to that of 18 years and older. Of the positive volunteers, 0.6% (6/996) were from Yanfolila's border health region. The average cost of XenoFil (entomology combined with serology) is 5,656,244 CFA francs (US$9070), and TAS has an average cost of 6,366,450 CFA francs (US$10209) in a survey conducted in one evaluation unit.

CONCLUSIONS

The new XenoFil approach proved to be an easy, effective, and relatively cheaper method for integrated LF surveillance in rural areas. From the perspective of integrated LF monitoring, XenoFil is needed for scaling up to other EU.

Mosquito Surveillance for West Nile Virus

Identifying the mosquitoes responsible for transmitting human disease-causing pathogens is of critical importance for effective control of mosquito-borne outbreaks. West Nile virus is often transferred by adult female mosquitoes in the genus Culex, which deposit eggs in a variety of aquatic habitats throughout the world. Herein we describe several methodological approaches to monitor these species in nature, as well as offering details for data collection and analysis.

From tissue engineering to mosquitoes: biopolymers as tools for developing a novel biomimetic approach to pest management/vector control

Background

Pest management has been facing the spread of invasive species, insecticide resistance phenomena, and concern for the impact of chemical pesticides on human health and the environment. It has tried to deal with them by developing technically efficient and economically sustainable solutions to complement/replace/improve traditional control methods. The renewal has been mainly directed towards less toxic pesticides or enhancing the precision of their delivery to reduce the volume employed and side effects through lure-and-kill approaches based on semiochemicals attractants. However, one of the main pest management problems is that efficacy depends on the effectiveness of the attractant system, limiting its successful employment to semiochemical stimuli-responsive insects. Biomaterial-based and bioinspired/biomimetic solutions that already guide other disciplines (e.g., medical sciences) in developing precision approaches could be a helpful tool to create attractive new strategies to liberate precision pest management from the need for semiochemical stimuli, simplify their integration with bioinsecticides, and foster the use of still underemployed solutions.

Approach proposed

We propose an innovative approach, called “biomimetic lure-and-kill”. It exploits biomimetic principles and biocompatible/biodegradable biopolymers (e.g., natural hydrogels) to develop new substrates that selectively attract insects by reproducing specific natural environmental conditions (biomimetic lure) and kill them by hosting and delivering a natural biopesticide or through mechanical action. Biomimetic lure-and-kill-designed substrates point to provide a new attractive system to develop/improve and make more cost-competitive new and conventional devices (e.g. traps). A first example application is proposed using the tiger mosquito Aedes albopictus as a model.

Conclusions

Biomaterials, particularly in the hydrogel form, can be a useful tool for developing the biomimetic lure-and-kill approach because they can satisfy multiple needs simultaneously (e.g., biomimetic lure, mechanical lethality, biocompatibility, and bioinsecticide growth). Such an approach might be cost-competitive, and with the potential for applicability to several pest species. Moreover, it is already technically feasible, since all the technologies necessary to design and configure materials with specific characteristics are already available on the market.

Graphical Abstract