Resistance of adult Culex pipiens quinquefasciatus to four common insecticides in Guiyang City / 中华地方病学杂志

Objective To investigate the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides in Guiyang City.Methods Larvae of Culex pipiens quinquefasciatus were collected from 8 areas of Guiyang City by larval scoop method from August to September 2015,and raised in the laboratory to adult Culex pipiens quinquefasciatus.Contact tube method was used to determine the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides,and knockdown rate of 1 h and mortality rate of 24 h recovery were calculated.The resistance level was judged according to the mortality rate:＜ 90％ was in the resistant group (R);90％-＜ 98％ was in the potential resistant group (M);and ≥98％ was in the sensitive group (S).Results The adult Culex pipiens quinquefasciatus were exposed to 7.70 g/L dichlorvos,3.30 g/L propoxur,0.25 g/L beta-cypermethrin and 0.20 g/L dehamethrin,knockdown rates of 1 h were 57.78％ (52/90)-91.11％ (82/90),86.67％ (78/90)-100.00％ (90/90),23.33％ (21/90)-77.78％ (70/90) and 27.78％ (25/90)-88.89％ (80/90),respectively;and mortality rates of 24 h recovery were 61.11％ (55/90)-94.44％ (85/90),90.00％ (81/90)-97.78％ (88/90),23.33％ (21/90)-73.33％ (66/90) and 21.11％ (19/90)-72.22％ (65/90),respectively.Conclusion Adult Culex pipiens quinquefasciatus in Guiyang City have developed some resistance to four common insecticides,in which the mosquito has a higher resistance to pyrethroid insecticides such as beta-cypermethrin and deltamethrin.

Bedbugs (Cimicidae infestation): the worldwide renaissance of an old partner of human kind

Bedbugs have been known as a human parasite for thousands of years, but scientific studies about this insect are recent and limited. Cimex lectularius, the common bedbug, was a well-known parasite in human dwellings until the end of the Second World War. Nowadays, bedbugs are considered uncommon in the industrialized world. Anecdotal reports suggest that bedbugs are getting more common in the United States, Canada, and United Kingdom. In Brazil, there are few reports about bedbug infestations in the literature. The aim of this article was to alert physicians, especially in Brazil, about this ectoparasitosis, including aspects of the bedbug biology, their parasitism in human host, treatment and prophylaxis.

Screening and characterization of human phage antibody to permethrin / 中国医师杂志

Objective To screen permethrin human single-chain variable region (scFv) antibody for aims of developing rapid detection kit. Methods Phage display technology was used in this study. Permethrin was solid phase coated on Nunc plate as antigen. Semi-synthetic single-chain variable region of human antibody library technology was applied, and single chain variable region was screened from phage antibody library after 3 rounds "adsorption - elution - amplification" of the selection process. 100 clones were random selected as resistance to permethrin clones , enzyme-linked immunosorbent assay (ELISA), crossreactivity and competitive inhibition experiments were used to validate permethrin binding activity with strong scFv clones from the selected phage antibody clones plasmid. The plasmid was digested with restriction enzyme Sfi Ⅰ / Not Ⅰ and subcloned into pCANTAB5E vector. After transformed into E. coli XL1BIue, the plasmid was identified by restriction enzyme analysis. Results After screening in 100 clones, 18 clones had high ELISA absorbance values ( A value) at 490nm wavelength ( A490nm), then bovine serum albumin (BSA) cross-reactions identified five weak cross-reaction. Combined with the triplicate ELISA and competitive inhibition experiment results, one positive clone was acquired at last. And this clone was subcloned into pCANTAB5E vector and transformed into competent cells XL1-Blue. Conclusion Plasmid fragment was consistent with the purpose, which provided the foundation for further study of its specific affinity.

Estudio de la resistencia en una cepa de Culex quinquefasciatus, procedente de Medellín, Colombia

Para conocer el estado de la resistencia en una cepa de Culex quinquefasciatus, procedente de una localidad de la ciudad de Medellín, Colombia, se determinaron los niveles de susceptibilidad y/o resistencia a 5 insecticidas organofosforados (malatión, metil-pirimifos, clorpirifos, temefos y fentión), 4 piretroides (cipermetrina, deltamemetrina, permetrina y lambdacialotrina) y un carbamato (propoxur). Se observó resistencia a todos los insecticidas organofosforados, aunque con valores relativamente menores para metil-pirimifos y fentión. No se encontró resistencia a los piretroides lambdacialotrina y cipermetrina, ni al carbamato propoxur, insecticidas que pueden ser muy útiles para el control de mosquitos de Colombia. Se demostró mediante el uso del sinergista piperonil butóxico que las oxidasas de función múltiple desempeñaron una función importante en la resistencia a los insecticidas organofosforados y piretroides. El uso del S.S.S. tributil fosfotritiado reveló que la sobreproducción de esterasas inespecíficas constituyó un mecanismo de resistencia para los insecticidas organofosforados, excepto metil-pirimifos y para los piretroides excepto lambdacialotrina. Este resultado debe tenerse en cuenta en las estrategias que se vayan a usar para el control de Culex quinquefasciatus de Colombia. Estos 2 mecanismos de resistencia no son responsables de la resistencia al carbamato propoxur. El análisis electroforético reveló la presencia de las esterasas B1, A6 y B6, que presumimos tienen una función importante en la resistencia.

The levels of susceptibility and/or resistance to 5 organophosphate insecticides (malathion, methyl-pyrimifos, clorpirifos, temephos and fenthion), 4 pyrethroids (cypermethrin, deltamethrin, permethrin and lambda-cyhalothrin), and a carbamate (propoxur) were deternmined in order to know the state of resistance in a strain of Culex quinquefasciatus from a locality of the city of Medellín, Colombia. Resistance to all organophosphate insecticeides, though with relatively lower values for methyloirimifos and fenthion, was observed. No resistance to lambda-cyhalothrin and cypermethrin or to propoxur was found. These insecticides may be useful for the control of mosquitoes in Colombia. It was demonstrated by using the piperonil butoxide sinergist that the oxidases of multiple function played an important role in the resistance to organophosphate insecticides and pyrethroids. The utilization of S.S.S. tributyl phosphotritiate revealed that the superproduction of unspecific esterases was a mechanism of resistance to organophosphate insecticides, except methyl-pirimifos and for perythroids, exceptlambda-cyhalothrin. This result should be taken into consideration for the strategies to be used to control Culex quinquefasciatus in Colombia. These two mechanism of resistance are not responsible for the resistance to propoxur. The electrophoretic analysis showed the presence of esterases B1, A6 and B6, which seem to have an important function in resistance.