Mosquitoes (Diptera: Culicidae) are major vectors of important pathogens and parasites. Malaria, dengue fever, yellow fever, filariasis, schistosomiasis and Japanese encephalitis cause millions of ...deaths every year. Mosquito control is being challenging due to the development of pesticide resistance and negative environmental concerns. In this scenario, plants employed in traditional Asian medicine may be alternative sources of newer and effective mosquitocides. In this research, we evaluated the larvicidal activity of Kadsura heteroclita leaf essential oil (EO) and its major chemical constituents (δ-Cadinene, Calarene and δ-4-Carene) against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the filariasis vector Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy. GC-MS revealed that the essential oil of K. heteroclita contained 33 compounds. The major chemical components were δ-Cadinene (18.3%), Calarene (14.8%) and δ-4-Carene (12.5%). The EO had a significant toxic effect against early third-stage larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus, with LC50 values of 102.86, 111.79 and 121.97 µg/mL. The three major constituents extracted from the K. heteroclita EO were tested individually for acute toxicity against larvae of the three mosquito vectors. δ-Cadinene, Calarene and δ-4-Carene appeared most effective against An. stephensi (LC50 = 8.23, 12.34 and 16.37 µg/mL, r espectively) followed by Ae. aegypti (LC50 = 9.03, 13.33 and 17.91 µg/mL), and Cx. quinquefasciatus (LC50; = 9.86, 14.49 and 19.50 µg/mL). Overall, this study adds knowledge to develop newer and safer natural larvicides against malaria, dengue and filariasis mosquito.
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•Mosquito control is challenging, due to resistance development to synthetic pesticides.•We studied synergistic binary mixtures of Apiaceae oils on Culex quinquefasciatus ...larvae.•Trachyspermum ammi+Pimpinella anisum (1:2) and Smyrnium olusatrum+P. anisum (1:1) LC50 were 15.2 and 16.9μlL−1.•Exposure to binary mixtures reduced Culex quinquefasciatus fertility and natality.•Germacrone, isofuranodiene and (E)-anethole LC50 were 18.6mgL−1, 33.7mgL−1 and 24.8μlL−1, respectively.
The recent outbreaks of mosquito-borne diseases, such as chikungunya and Zika virus, highlighted the pivotal importance of effective mosquito control programs. Nowadays, Culicidae management is being challenging, due to the rapid development of resistance to synthetic pesticides and the spread of highly invasive mosquito vectors worldwide. This research explored the chemical composition of four Apiaceae essential oils (EOs) from Trachyspermum ammi, Smyrnium olusatrum, Pimpinella anisum and Helosciadium nodiflorum and their potential as sources of synergistic binary mixtures with high effectiveness against larvae of the filariasis vector Culex quinquefasciatus. The essential oils were all highly toxic to the larvae, showing LC50 of 17.6, 17.5, 25.9 and 20.6μlL−1, respectively. GC–MS analysis put in evidence thymol, (E)-anethole, myristicin and (Z)-β-ocimene, and isofuranodiene and germacrone as the main essential oil components, respectively. Three effective EOs were selected to prepare binary mixtures. T. ammi+P. anisum (ratio 1:2) and S. olusatrum+P. anisum (ratio 1:1) were the most toxic larvicidal blends, showing LC50 of 15.2 and 16.9, μlL−1, respectively. LT50 values were 45 and 30min, respectively. Notably, short time exposure to both binary mixtures strongly reduced emergence rates, fertility and natality of C. quinquefasciatus that survived after the treatment at the larval stage. Larvicidal assays assessing the acute toxicity of EO main constituents, i.e. germacrone, isofuranodiene and (E)-anethole, were carried out. LC50 were 18.6mgL−1, 33.7mgL−1 and 24.8μlL−1. Overall, our results pointed out the promising potential of these EOs to develop cheap and effective mosquito larvicides, as well as the importance to consider the synergistic effects among the tested botanicals during the design of novel mosquito larvicides.
The management of parasites, insect pests and vectors requests development of novel, effective and eco-friendly tools. The development of resistance towards many drugs and pesticides pushed ...scientists to look for novel bioactive compounds endowed with multiple modes of action, and with no risk to human health and environment. Several natural products are used as alternative/complementary approaches to manage parasites, insect pests and vectors due to their high efficacy and often limited non-target toxicity. Their encapsulation into nanosystems helps overcome some hurdles related to their physicochemical properties, for instance limited stability and handling, enhancing the overall efficacy. Among different nanosystems, micro- and nanoemulsions are easy-to-use systems in terms of preparation and industrial scale-up. Different reports support their efficacy against parasites of medical importance, including
,
and
as well as agricultural and stored product insect pests and vectors of human diseases, such as
and
mosquitoes. Overall, micro- and nanoemulsions are valid options for developing promising eco-friendly tools in pest and vector management, pending proper field validation. Future research on the improvement of technical aspects as well as chronic toxicity experiments on non-target species is needed.
Discovering and validating effective drugs to manage arthropod-borne diseases (ABD) is a timely and important research challenge with major impacts on real-world control programs at the time of quick ...resistance development in the targeted pathogens. This editorial highlights major research advances in the development of drugs for the control of vector-borne diseases, with a significant focus on malaria, Chagas disease, dengue, human African trypanosomiasis, leishmaniasis, and Zika. Broad reviews providing new insights on ABD recently published in
have also been covered in "The Editors' pick" section.
Mosquitoes (Diptera: Culicidae) represent an important threat to millions of people worldwide, since they act as vectors for important pathogens, such as malaria, yellow fever, dengue and West Nile. ...Control programmes mainly rely on chemical treatments against larvae, indoor residual spraying and insecticide-treated bed nets. In recent years, huge efforts have been carried out to propose new eco-friendly alternatives, with a special focus on the evaluation of plant-borne mosquitocidal compounds. Major examples are neem-based products (Azadirachta indica A. Juss, Meliaceae) that have been proven as really effective against a huge range of pests of medical and veterinary importance, including mosquitoes. Recent research highlighted that neem cake, a cheap by-product from neem oil extraction, is an important source of mosquitocidal metabolites. In this review, we examined (i) the latest achievements about neem cake metabolomics with special reference to nor-terpenoid and related content; (ii) the neem cake ovicidal, larvicidal and pupicidal toxicity against Aedes, Anopheles and Culex mosquito vectors; (iii) its non-target effects against vertebrates; and (iv) its oviposition deterrence effects on mosquito females. Overall, neem cake can be proposed as an eco-friendly and low-cost source of chemicals to build newer and safer control tools against mosquito vectors.
Mosquitoes represent an important threat for lives of millions of people worldwide, acting as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile. In addition, ...pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. Here, we investigated the mosquitocidal and antibacterial properties of
Aloe vera
leaf extract and silver nanoparticles synthesized using
A. vera
extract
.
Mosquitocidal properties were assessed in laboratory against larvae (I-IV instar) and pupae of the malaria vector
Anopheles stephensi
. Green-synthesized silver nanoparticles were tested against
An. stephensi
also in field conditions. Antibacterial properties of nanoparticles were evaluated against
Bacillus subtilis
,
Klebsiella pneumoniae
, and
Salmonella typhi
using the agar disk diffusion and minimum inhibitory concentration protocol. The synthesized silver nanoparticles were characterized by UV–vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In laboratory conditions, the
A. vera
extract was toxic against
An. stephensi
larvae and pupae, even at low dosages. LC
50
were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae). Green-synthesized silver nanoparticles were highly toxic against
An. stephensi
. LC
50
were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae). In field conditions, the application of
A. vera
-synthesized silver nanoparticles (10 × LC
50
) leads to
An. stephensi
larval reduction of 74.5, 86.6, and 97.7 %, after 24, 48, and 72 h, respectively. Nanoparticles also showed antibacterial properties, and the maximum concentration tested (150 mg/L) evoked an inhibition zone wider than 80 mm in all tested bacterium species. This study adds knowledge about the use of green synthesis of nanoparticles in medical entomology and parasitology, allowing us to propose
A. vera
-synthesized silver nanoparticles as effective candidates to develop newer and safer mosquitocidal control tools.
Neem seed oil (NSO) of Azadirachta indica (Meliaceae) contains more than 100 determined biologically active compounds, and many formulations deriving from them showed toxicity, antifeedancy and ...repellence against a number of arthropod pests. However, it is widely known that botanical products can differ in their chemical composition and bioactivity, as function of the production site and production process. We used high-performance thin layer chromatography (HPTLC) to investigate differences in chemical constituents of NSOs from three production sites. HPTLC analyses showed several differences in chemical abundance and diversity among NSOs, with special reference to limonoids. Furthermore, the three NSOs and their fractions of increasing polarities i.e. ethyl acetate (EA) fraction and butanol (BU) fraction were evaluated for larvicidal toxicity and field oviposition deterrence against the Asian tiger mosquito, Aedes albopictus, currently the most invasive mosquito worldwide. Results from bioactivity experiments showed good toxicity of NSOs and EA fractions against A. albopictus fourth instar larvae (with LC₅₀values ranging from 142.28 to 209.73 ppm), while little toxicity was exerted by BU fractions. A significant effect of the production site and dosage was also found and is probably linked to differences in abundance of constituents among samples, as highlighted by HPTLC analyses. NSOs and EAs were also able to deter A. albopictus oviposition in the field (effective repellence values ranging from 98.55 to 70.10 %), while little effectiveness of BU fractions was found. Concerning ovideterrent activity, no difference due to the production site was found. This is the first report concerning larvicidal toxicity of NSO against A. albopictus and ovideterrence against Culicidae in the field. The chance to use chemicals from the NSO EA fraction seems promising, since they are effective at lower doses, if compared to synthetic products currently marketed, and could be an advantageous alternative to build newer and safer mosquito control tools.
The Dipteran family Tephritidae (true fruit flies) comprises more than 5000 species classified in 500 genera distributed worldwide. Tephritidae include devastating agricultural pests and highly ...invasive species whose spread is currently facilitated by globalization, international trade and human mobility. The ability to identify and exploit a wide range of host plants for oviposition, as well as effective and diversified reproductive strategies, are among the key features supporting tephritid biological success. Intraspecific communication involves the exchange of a complex set of sensory cues that are species- and sex-specific. Chemical signals, which are standing out in tephritid communication, comprise long-distance pheromones emitted by one or both sexes, cuticular hydrocarbons with limited volatility deposited on the surrounding substrate or on the insect body regulating medium- to short-distance communication, and host-marking compounds deposited on the fruit after oviposition. In this review, the current knowledge on tephritid chemical communication was analysed with a special emphasis on fruit fly pest species belonging to the
, and
genera. The multidisciplinary approaches adopted for characterising tephritid semiochemicals, and the real-world applications and challenges for Integrated Pest Management (IPM) and biological control strategies are critically discussed. Future perspectives for targeted research on fruit fly chemical communication are highlighted.
Plant-insect interactions are one of the most fascinating fields of research attracting biologists, entomologists, botanists, as well as a wide range of multidisciplinary researchers ...
Ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide, affecting humans, livestock, and companion animals.
Hyalomma dromedarii
is the predominant tick ...species infesting camels, and its effective control is of pivotal importance. In this research, we compared the phytoefficacy of safranin (SF), a fluorescent dye applied as an acaricide for the first time, to that of tetramethrin (TM) against engorged females of
H. dromedarii
through in vitro immersion bioassays. Furthermore, the effect of SF exposure was evaluated on the reproductive potential of surviving tick females. Different concentrations of SF (0.03, 0.06, 0.3, 1, and 4 %
w
:
v
) and TM (0.03, 0.13, 0.5, 2, and 4 %) were prepared in distilled water and administered to engorged females of
H. dromedarii
. SF-treated ticks were illuminated with a light source for 30 min post-treatment (PT). Photophysical properties of SF were studied, and the relative efficacy of the used light source and sunlight was calculated. Results showed that the minimum least concentration that causes 100 % acaricidal effect was 4 % PT with SF and TM, for 8 and 48 h, respectively. LC
50
values 8 and 24 h PT were 0.08, 0.03 and 0.78, 0.20 %, respectively. Comparing LC
50
and LC
90
2 h PT, SF was 33 and 22 times more potent than TM. LT
50
of 4 % SF and TM were 0.80 and 2.17 h, respectively. Treatment with the lowest concentrations of SF and TM induced reduction of the number of ovipositing females, eggs per female, ticks laying viable eggs, and hatched eggs. Overall, our results highlighted that SF is highly effective if compared to TM, allowing use to candidate it for the development of novel and safer acaricides.
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