Growing resistance to pesticides sees return of bedbugs

 

Bedbugs are making an international comeback with population growth estimates running as high as 500 per cent per year, writes DICK AHLSTROM, Science Editor

Good night, sleep tight,

Don’t let the bedbugs bite.

And if they do

Then take your shoe

And knock ‘em ‘til

They’re black and blue!

AS YOU TUCK yourself into bed tonight consider this – you may be sharing that cosy space with unwanted guests. Bedbugs are enjoying a worldwide comeback, something that new research puts down to pesticide resistance.

Entomologists in Ohio State University this morning publish the first genetic study of bedbugs and the news is all good – at least for the bedbugs.

The analysis showed that the species currently enjoying a major international renaissance, Cimex lectularius, has managed to pick up a number of genetic changes to help it survive treatments with pesticides.

“The resurgence of bedbugs poses an urgent situation, as infestations are rampant globally, nationally and locally,” the authors write in their research paper, published by the online journal, PLoS ONE.

“They have exploded over the last five years, and frequent air travel means it can get anywhere,” said Trinity College Dublin entomologist Dr Bridget O’Neill.

“They are not that common but certainly have been reported here. They are brought about by people so places they are found include hotels, hostels and BBs,” added Dr Eugenie Regan of the National Biodiversity Centre in Waterford.

Bedbugs had largely disappeared, with DDT putting paid to the little beasties. Many people today will only know them by repute, or as part of a snide comment when referring to dodgy places where a person might have slept the night. They are no laughing matter however, as the authors point out.

For starters they are flightless, nocturnal blood-suckers, with human blood their preferred tipple. “Bedbug infestations pose grave economic concerns and quality-of-life issues for households,” the authors say.

The insect bites itch but the skin irritation can also lead to secondary infections such as impetigo. This is separate to the psychological distress that comes from thinking about the bugs as they prepare to feast once you are asleep. Bedbug infestations can “result in anxiety, insomnia or worsening of an existing mental health condition,” the authors say.

The insects have a long association with us, with well-preserved bedbug remains dating back to 1350 recovered from an archaeological dig in Egypt, the authors write.

During the last decade the resurgence of C lectulariushas been recorded around the world from North America and Europe to Australia and Eastern Asia. Increases in annual bedbug populations range from 100 per cent to 500 per cent annually, the researchers say.

C lectulariuscan live for months without feeding,” Dr O’Neill said. Hotel infestations are common and once installed guests who place luggage on the floor may pick up unexpected hitch-hikers and obligingly bring them to a new home.

They are also particularly successful in large apartment complexes where they are easily spread, she added. They hide in bedclothes but also in furnishing, carpets and even behind wallpaper.

Given their growing importance, the Ohio State researchers decided to study the insect’s DNA, looking for possible genes associated with pesticide resistance. This might in turn point towards new control methods that do not rely on the currently ineffective pesticide products.

The researchers believe theirs is the first extensive analysis of bedbug DNA. Their approach involved using “454 sequencing technology” to look for gene expression within the bugs.

They wanted to know if the bugs expressed certain enzymes known to enable other insect species to resist pesticides. They also wanted to learn whether the resistance was due to single mutations in certain genes or more substantial DNA changes.

“Pinpointing such defence mechanisms and the associated genes could lead to the development of novel methods of control that are more effective,” said corresponding author Prof Omprakash Mittapalli of the university’s Agricultural Research and Development Centre.