A laboratory evaluation of the IGR, PH 60-40,against Culex pipiens pallens and Culex tritaeniorhynchus

Abstract Background: In 2009, China CDC found the distribution of Culex tritaeniorhynchus and Aedes albopictus in Motuo county, Linzhi, Xizang and isolated the epidemic encephalitis V virus from Culex tritaeniorhynchus. However, with the road opend in Motuo County, the trade between people and mosquitoes transmission were more frequent. To illustrate patterns of mosquito population in Linzhi, Xizang, a mosquitoes surveillance was carried.Methods: Adult mosquitoes were collected by light traps and human landing catches, larva by container survey in six counties of Linzhi during August and September 2019. The trapped adult mosquitoes were initially counted and identified according to morphological criteria, and a part of mosquitoes were further identified by PCR. The monitoring data were recorded by Excel 2007, analyzed by SPSS 20.0 software and R.Results: Eight species of mosquitoes belonging to four genera were identified. Culex pipiens pallens (86.80%), Armigeres subalbalus (5.29%) and Aedes vexans (2.99%) were the top three species coolected by 164 light traps on 12 nights with the average mosquito density was 21.20 (mosquitoes per trap per night); Aedes albopictus were only collected in Chayu County Xiachayu Town by human landing catches with high average mosquito density (26.33 mosquitoes per hour per person). The larva were collected from waste tires, cement tanks and drums in Bomi, Milin and Lang Counties. The results of molecular identification are consistent with morphological identification. Aedes albopictus and Culex orientalis were newly recorded species for the first time. It is preliminarily speculated that there is a high potential risk of dengue fever in Xiachayu Town and a certain epidemic risk of Japanese encephalitis, while the risk of malaria is low in Linzhi.Conclusion: Mosquitoes had heterogeneous distribution throughout Linzhi, Xizang. The dominant mosquito species are Culex pipiens pallens. It is emphasized to carry out mosquito surveillance again during the peak period of mosquito activities so as to better understand the distribution and composition of local mosquitoes and assess the mosquito-borne disease risk in this area.

Download Full-text

MiR-4448 is involved in deltamethrin resistance by targeting CYP4H31 in Culex pipiens pallens

Parasites & Vectors ◽

10.1186/s13071-021-04665-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Xixi Li ◽

Shengli Hu ◽

Haitao Yin ◽

Hongbo Zhang ◽

Dan Zhou ◽

...

Keyword(s):

Culex Pipiens ◽

Oral Feeding ◽

Cell Counting ◽

Luciferase Reporter ◽

Culex Pipiens Pallens ◽

Deltamethrin Resistance ◽

Regulatory Functions ◽

Pipiens Pallens

Abstract Background Culex pipiens (Cx. pipiens) complex, which acts as a vector of viruses and is widespread and abundant worldwide, including West Nile virus, Japanese encephalitis virus, and Sindbis virus, can cause serious vector-borne diseases affecting human health. Unfortunately, mosquitoes have developed deltamethrin resistance because of its long-term overuse, representing a major challenge to mosquito control. Understanding the molecular regulatory mechanisms of resistance is vital to control mosquitoes. MicroRNAs (miRNAs) are short non-coding RNAs that have been demonstrated to be important regulators of gene expression across a wide variety of organisms, which might function in mosquito deltamethrin resistance. In the present study, we aimed to investigate the regulatory functions of miR-4448 and CYP4H31 in the formation of insecticidal resistance in mosquito Culex pipiens pallens. Methods We used quantitative real-time reverse transcription PCR to measure miR-4448 and CYP4H31 (encoding a cytochrome P450) expression levels. The regulatory functions of miR-4448 and CYP4H31 were assessed using dual-luciferase reporter assays. Then, oral feeding, RNA interference, and the American Centers for Disease Control and Prevention bottle bioassay were used to determine miR-4448’s association with deltamethrin resistance by targeting CYP4H31in vivo. Cell Counting Kit-8 (CCK-8) was also used to detect the viability of pIB/V5-His-CYP4H31-transfected C6/36 cells after deltamethrin treatment in vitro. Results MiR-4448 was downregulated in the deltamethrin-resistant strain (DR strain), whereas CYP4H31 was downregulated in deltamethrin-susceptible strain. CYP4H31 expression was downregulated by miR-4448 recognizing and binding to its 3′ untranslated region. Functional verification experiments showed that miR-4448 overexpression resulted in lower expression of CYP4H31. The mortality of miR-4448 mimic-injected DR strain mosquitoes was higher than that of the controls. CCK-8 assays showed that CYP4H31 decreased cellular resistance to deltamethrin in vitro and the mortality of the DR strain increased when CYP4H31 was knocked down in vivo. Conclusions In mosquitoes, miR-4448 participates in deltamethrin resistance by targeting CYP4H31. The results of the present study increase our understanding of deltamethrin resistance mechanisms.

Download Full-text