{"id":471594,"date":"2026-05-28T17:01:08","date_gmt":"2026-05-28T17:01:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/471594\/"},"modified":"2026-05-28T17:01:08","modified_gmt":"2026-05-28T17:01:08","slug":"mosquitoes-can-become-attracted-to-common-insect-repellent-chemical-study-suggests-the-irish-times","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/471594\/","title":{"rendered":"Mosquitoes can become attracted to common insect repellent chemical, study suggests \u2013 The Irish Times"},"content":{"rendered":"

It is a spray used worldwide to protect humans from mosquito bites, but now research suggests Deet can become attractive to the insects if they associate it with feeding.<\/p>\n

Deet \u2013 which has the chemical name N,N-diethyl-meta-toluamide \u2013 is widely used in insect repellents, with the UK health security agency recommending products with 50 per cent Deet as the first choice to protect against mosquito bites.<\/p>\n

Such protection is important given that in some countries mosquito bites can spread fatal diseases such as dengue, Japanese encephalitis, malaria and Zika.<\/p>\n

However, a new study suggests that mosquitoes can learn that the presence of Deet indicates the possibility of a blood meal.<\/p>\n

\u201cFor a long time, it was believed that repellents worked solely because of their chemical properties, either by being toxic or unpleasant to mosquitoes and driving them away, or by blocking their ability to detect humans. However, our findings suggest that the reaction can be modified by experience,\u201d said Prof Claudio Lazzari, from the University of Tours, France<\/a>. <\/p>\n

\u201cWe believe this represents a significant change in our understanding of repellents.\u201d<\/p>\n

[\u00a0Are there actually more biting insects in Ireland these days?Opens in new window<\/a>\u00a0]<\/p>\n

While studies have previously suggested mosquitoes were less bothered by Deet after first exposure, the team behind the new research said it had been unclear why this was.<\/p>\n

Writing in the Journal of Experimental Biology, the researchers said they initially observed how trapped mosquitoes attempted to bite a bag of warm blood that they could not quite reach.<\/p>\n

Further investigation revealed that 60 per cent of mosquitoes that fed when presented with warm blood alongside exposure to Deet subsequently showed biting attempts when exposed to Deet alone.<\/p>\n

This compared with 17 per cent of insects given no prior training, 13 per cent of mosquitoes previously presented with Deet alone, 17 per cent that previously fed on warm blood with no exposure to Deet and 23 per cent that previously fed on warm blood and were exposed to Deet but not simultaneously.<\/p>\n

In another test, the team found almost 60 per cent of mosquitoes that previously fed on blood while exposed to Deet subsequently attempted to reach and bite a researcher\u2019s Deet-treated hand. By contrast, untrained mosquitoes universally tried to bite the researcher\u2019s other, untreated hand.<\/p>\n

Dr Nina Stanczyk of ETH Z\u00fcrich university, who has previously studied the effectiveness of Deet towards mosquitoes, welcomed the research.<\/p>\n

[\u00a0Why growing mosquito numbers are driving the spread of tropical diseases in EuropeOpens in new window<\/a>\u00a0]<\/p>\n

\u201cMosquitoes have been shown to have impressive learning abilities, but the fact they can associate such a strong repellent smell with their food and are then attracted to it afterwards is remarkable, and important for us to be aware of for the future,\u201d she said.<\/p>\n

However, experts emphasised that the findings did not mean that travellers should ditch their Deet.<\/p>\n

\u201cPeople should understand that Deet does not lose its effectiveness through normal use, but only under specific laboratory conditions designed to reveal how it works on mosquitoes,\u201d said Lazzari.<\/p>\n

Prof Francesca Romana Dani, an entomologist at the University of Florence, who was not involved in the study, said it was unlikely that, under normal conditions, mosquitoes would change their response to Deet based on previous experience, not least as the same insect may encounter different repellents during subsequent blood meals.<\/p>\n

\u201cFurthermore, although a single mosquito can take multiple blood meals, they do so every few days, so it\u2019s important to evaluate how long the memory of a blood meal taken in the presence of Deet will last,\u201d she said.<\/p>\n

Stanczyk said travellers should continue wearing repellents with confidence. <\/p>\n

\u201cThe study authors state it was challenging to make mosquitoes feed a first time in the presence of Deet, and that the highest risk an association would form is when [the] repellent starts to wear off,\u201d she said.<\/p>\n

\u201cTherefore, the most important point for travellers is to regularly reapply repellent as instructed by the product label.\u201d \u2013 The Guardian<\/p>\n","protected":false},"excerpt":{"rendered":"It is a spray used worldwide to protect humans from mosquito bites, but now research suggests Deet can…\n","protected":false},"author":2,"featured_media":471595,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[1814,103,61,60],"class_list":["post-471594","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-france","tag-health","tag-ie","tag-ireland"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/471594","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=471594"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/471594\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/471595"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=471594"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=471594"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=471594"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}