Action needed over insecticide resistance in disease-causing mosquito – study

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Culex pipiens pipiens feeding on a human host. © Fabrizio Montarsi, CC BY 3.0, Wikipedia

Urgent action should be taken to manage insecticide resistance in a common species of mosquito known to be responsible for the spread of several diseases than affect humans and horses, according to researchers.

The study team in Casablanca set out to explore insecticide resistance in Culex Pipiens in the north African country of Morocco.

M’hammed Sarih and his colleagues, writing in Parasites & Vectors said control of Cx. pipiens with insecticides is the main way to control the arboviruses that the species can transmit, such as West Nile Virus and Rift Valley Fever Virus.

However, the efficiency of this approach has been hampered by the emergence of insecticide resistance.

Little was known about the insecticide-resistance status and underlying resistance mechanisms of field-collected populations of Cx. pipiens in Morocco, the researchers noted.

Mosquito adults from the city of Mohammadia in Morocco were reared from immature stages.

The level of susceptibility to insecticides was assessed using a standard World Health Organisation test.

The testing indicated that Cx. pipiens was resistant to all tested insecticides: lambda-cyhalothrin (49% mortality), permethrin (63% mortality), DDT (16% mortality), malation (52% mortality) and bendiocarb (39% mortality).

“These findings showed that wild populations of Cx. pipiens have developed resistance against the main insecticide families with different modes of action: organochlorines (DDT), organophosphates (malathion), carbamates (bendiocarb), pyrethroids (lambda-cyhalothrin, permethrin).

“Therefore, urgent action should be taken to manage the resistance in this species to maintain the effectiveness of arbovirus control.”

They also tested mosquitoes for two gene mutations linked to resistance, with one in particular, the L1014F kdr mutation, significantly associated with resistance to three tested insecticides in Cx. Pipiens.

Insecticide resistance and target site mutations (G119S ace-1 and L1014F kdr) of Culex pipiens in Morocco
Fatim-Zohra Tmimi, Chafika Faraj, Meriem Bkhache, Khadija Mounaji, Anna-Bella Failloux and M’hammed Sarih
Parasites & Vectors 2018 11:51 https://doi.org/10.1186/s13071-018-2625-y

The study, published under a Creative Commons License, can be read here

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