1. Managing Arthropod Vectors and Vector-Borne Diseases: One Health Helps
Arthropod-borne diseases represent a major risk for humans, livestock, pets and wildlife
worldwide. The rapid spread of highly aggressive arboviruses and parasites, along
with the development of resistance in their arthropod vectors, represent a huge challenge
for parasitology, medical entomology and tropical medicine. As highlighted by the
Centers for Disease Control and Prevention, to successfully fight arthropod-borne
diseases a One Health approach is valuable. Indeed, One Health points out that the
human health is strongly connected to the health of animals and the environment. The
main aim of One Health is to encourage the cooperation among multiple disciplines
to achieve the best health for humans, animals and the environment [1,2].
The present Special Issue includes articles by experts on arthropod vector ecology
and control, as well as on the prevention and treatment of arthropod-borne diseases.
Herein, special emphasis has been dedicated to three of the main dangerous groups
of arthropod-borne diseases: the ones caused by pathogens and/or parasites vectored
by mosquitoes (Diptera: Culicidae), tsetse flies (Diptera: Glossinidae) and hard ticks
(Ixodida: Ixodidae).
2. What Has Been Done
The proper management of mosquito populations is crucial to limit the spread of mosquito-borne
diseases, such as malaria, dengue, West Nile, chikungunya, Zika virus and lymphatic
filariasis. Therefore, developing novel biocontrol tools is a timely challenge; in
particular, entomopathogens may represent a valuable strategy to reduce synthetic
pesticide overuse against mosquitoes. Vivekanandhan et al. [3] provided interesting
insights on the efficacy of mycelial extracts of the entomopathogen Beauveria bassiana
(Bals.-Criv.) Vuill. against the filariasis vector Culex quinquefasciatus Say. The
authors pointed out relevant toxicity of B. bassiana-28 ethyl acetate extract on mosquito
larvae and pupae, showing that its efficacy was comparable to that of a commercial
insecticide based on B. bassiana-22. Moreover, the B. bassiana-28 extract was chemically
characterized through GC-MS analyses and its impact on C. quinquefasciatus in terms
of histological damages showed midgut tissue lysis [3].
A further interesting multidisciplinary approach to develop novel and eco-friendly
mosquito insecticides is the exploitation of botanical secondary metabolites for pesticide
preparation, due to their multiple mechanisms of action making resistance development
unlikely [4]. The present Special Issue includes a research [5] focusing on the evaluation
of Acacia nilotica (L.) Willd. ex Delile (Fabaceae) seed oil and seed pod extract
against three important mosquito species: Anopheles stephensi Liston, Aedes aegypti
L. and Cx. quinquefasciatus. The authors assessed their larvicidal and adulticidal
potential, after evaluating the chemical composition of both tested plant-borne products.
In particular, about larvicidal effects, they obtained noteworthy LC50 values, always
lower than 15 mg/L, in full agreement with the criteria recently reported by Pavela
[6] and Pavela et al. [7], for the identification of plant essential oils and extracts
with highly promising mosquito larvicidal potential.
Still on the advantages of exploiting plants as reservoirs of interesting compounds
in the fight against parasites, this Special Issue contains insights on “green” drug
development against another dangerous arthropod-borne disease, the human African trypanosomiasis
(HAT), caused by Trypanosoma brucei parasites, which are vectored by tsetse flies
(Diptera: Glossinidae). Ngahang Kamte and coworkers [8] studied the inhibition of
T. brucei TC221 by six essential oils extracted from aromatic plants traditionally
used in Cameroon for pharmacological purposes, characterizing the oil chemical composition
by GC-MS. Selected major constituents from the essential oils were also tested. The
oils from Azadirachta indica A. Juss (Meliaceae), Aframomum daniellii (Hook. F.) K.
Schum. (Zingiberaceae) and Echinops giganteus A. Rich. (Asteraceae) achieved low IC50
values (i.e., about 10 µg/mL or even lower), as well as selectivity towards mouse
embryonic fibroblasts Balb/3T3. Overall, the authors outlined a successful approach
to exploit Cameroonian flora as a reservoir for isolating novel products to develop
novel and effective HAT drugs [8].
The third highly dangerous group of arthropod-borne diseases considered by this Special
Issue is represented by tick-borne diseases (TBDs). Ticks transmit a wide diversity
of pathogens causing a number of TBDs [2]. Under the One Health framework, insights
on ecology, monitoring and control of hard ticks are welcomed. Herein, Torina et al.
[9] proposed a geographical information system (GIS)-based approach for integrated
strategies of tick surveillance and control, which is of interest for public health
actions. The study was carried out in a natural reserve of Southern Italy (Monte Pellegrino,
close to Palermo, in Sicily). Solid findings based on three years of collected data
were retrieved, particularly about Ixodes ventalloi Gil Collado and Hyalomma lusitanicum
Koch in two distinct sites; GIS characterized the environmental characteristics of
each site, analyzing tick species abundance in relation to time and space [9].
The Special Issue continues with a review by Dente et al. [10] focused on the importance
to strengthen arbovirus surveillance in Mediterranean and Black Sea countries within
the One Health framework. The authors carefully examined surveillance systems for
West Nile, chikungunya, dengue and Rift Valley fever viruses, considering the various
human, animal, entomological and environmental sectors involved. The criteria proposed
in the conceptual framework developed by the authors to describe integrated surveillance
were consistently reported in the context of researches and programs related to integrated
surveillance of the above-mentioned arboviral diseases. Notably, these criteria may
facilitate the identification and description of operationalized One Health surveillance.
Then, the Special issue ends with a Benchmark article by Brisola Marcondes and Benelli
[11], which critically focused on tenuous links among mosquito bites, parasites and
pathogens transmitted by these insects, and cancer, stressing that the WHO International
Agency for Research on Cancer Monograph Working Group classified Plasmodium falciparum
infection in holoendemic areas as “probably carcinogenic to humans” (group 2A) [12,13].
3. The Future of One Health: Forthcoming Challenges for Entomology
Overall, we are fully aware that the studies published in this Special Issue cannot
fully represent the astonishing diversity of the research efforts attempted by scientists
working in entomology and parasitology. There is a long and winding road to translate
the One Health criteria into practice. On the other hand, we feel that the articles
included represent useful examples, boosting the integrated management of three major
groups of arthropod vectors of high public health importance.
Besides strengthening One Health research on these important vectors and vector-borne
diseases, it is also expected that the present efforts will be useful to promote future
multidisciplinary studies on other arthropod parasites and vectors, such as triatomine
bugs, sandflies, bed bugs, tabanids, biting midges and botflies (to cite just some
examples), which currently cause remarkable medical and veterinary issues, nevertheless
suffering from less research on their basic biology, ecology, monitoring and management
when compared to mosquitoes and hard ticks.