Background
The recent reports of
Aedes aegypti
and
Ae
.
albopictus
populations in Turkey, in parallel with the territorial expansion identified in several surrounding countries, have raised concerns about the establishment and re-establishment of these invasive
Aedes
mosquitoes in Turkey. This cross-sectional study was performed to detect
Aedes aegypti
and
Ae
.
albopictus
in regions of recent incursions, and screen for viral pathogens known to be transmitted elsewhere by these species.
Methodology
Mosquitoes were collected at several locations in Artvin, Rize and Trabzon provinces of the Black Sea region during 2016–2017, identified morphologically, pooled and analyzed via generic or specific nucleic acid amplification assays. Viruses in positive pools were identified by product sequencing, cell culture inoculation and next generation sequencing (NGS) in selected specimens.
Principal findings
The study group comprised 791 specimens.
Aedes albopictus
was the most abundant species in all locations (89.6%), followed by
Ae
.
aegypti
(7.8%) and
Culex pipiens
(2.5%). Mosquitoes were screened for viruses in 65 pools where fifteen (23.1%) were reactive. The infecting strains was identified as West Nile virus (WNV) in 5 pools (7.7%) with
Ae
.
albopictus
or
Cx
.
pipiens
mosquitoes. The obtained WNV sequences phylogenetically grouped with local and global lineage 1 clade 1a viruses. In 4 (6.2%) and 6 (9.2%) pools, respectively, cell fusing agent virus (CFAV) and
Aedes
flavivirus (AEFV) sequences were characterized. NGS provided a near-complete AEFV genome in a pool of
Ae
.
albopictus
. The strain is provisionally called “AEFV-Turkey”, and functional analysis of the genome revealed several conserved motifs and regions associated with virus replication. Merida-like virus Turkey (MERDLVT), a recently-described novel rhabdovirus, was also co-detected in a
Cx
.
pipiens
pool also positive for WNV.
Conclusions/Significance
Invasive
Aedes
mosquitoes are established in certain locations of northeastern Turkey. Herein we conclusively show the role of these species in WNV circulation in the region. Biosurveillance is imperative to monitor the spread of these species further into Asia Minor and to detect possible introduction of pathogens.
In this study, potential of the entomopathogenic fungi (EPF) isolates from dead samples of Orosanga japonica (Melichar) (Hemiptera: Ricaniidae) was evaluated. Infected specimens with fungi results confirmed that the samples were Beauveria bassiana after morphological and molecular identification. Amplicons produced two haplotypes (h = 2), which included one polymorphic site after sequence and named isolates 1 and 2. Two haplotypes were rooted with MK229193.1, MG345084.1 B. bassiana Genbank samples. Two-year survey results of the EPF effects revealed the highest mortality and natural infection rates in the field. Natural mortality rates varied between 80.35% (Fındıklı-August) and 94.8% (Çayeli-September) in 2018 and between 79.82% (Alipaşa-August) and 97.75% (Fındıklı- September) in 2019. For nymphs, the lowest LT50 value was found at 2.92 days for isolate 1 and 2.56 days for isolate 2, with a concentration of 1 × 106 conidia/ml, using the leaf dipping method. For adults, the lowest LT50 value was found at 3.02 days for isolate 1 and 3.15 days for isolate 2, with a concentration of 1 × 106 conidia/ml, using the direct spraying method. Nymph LT50 values were found a little bit lower than adults. Direct spraying methods results gave a high LT50 value for nymph in contrast to adult. Although the LT50 ratios gave high/low degree in different isolates, methods and life stages, non-significant differences were found between each other’s (p > 0.05). In general, B. bassiana natural infection rates were found high in August and September during the 2 years. Efficacy of the two isolates, which derived from naturally infected O. japonica specimens, increased with concentration. The two isolates can potentially be used for O. japonica integrated management, as a fungal biocontrol agent, but their toxicological effects on beneficial insects, such as honeybees, will need to be determined.
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