The newest recruits for the battle against moths will be the smallest pest control team in town.
Rentokil plans to release entosite parasitoid wasps into the nooks and crannies of museums, heritage sites and homes to stop moth infestations.
The minuscule wasps measure less than 0.5mm in size, and they stop moths reproducing by parasitising their eggs and laying their own eggs inside the moth eggs, preventing the larvae from hatching.
In place of spraying the areas with toxic insecticides, the pest control company says using the wasps is a sustainable way to get rid of the moths. It is also safer for the fabrics, as particularly delicate and valuable items can be damaged by fumigation or heat treatments used to get rid of moths; using wasps instead gets round this problem.
This is why the new treatment is particularly useful in museums, historic venues and theatre collections, which often have priceless textile works which can not risk damage from harsh removal methods.
Paul Blackhurst, head of technical academy at Rentokil, said:“Entosite is a revolutionary non-toxic solution that sensitively and effectively eliminates clothing moth infestations from delicate, fabric and textile items of sentimental or historic value.”
The wasps provide continuous protection against the infestations as their life cycle continues after their eggs hatch, meaning wasps emerge that will seek out and destroy any new moth eggs. They eventually die out once there are no more eggs to consume.
They are released from specially designed sachets to be placed in wardrobes, drawers or anywhere else moths may hide, which have a slow, timed release meaning there is a steady supply of wasps over several weeks.
The wasps commonly seen at picnics are social wasps, but their parasatoid cousins are rarely seen because they are so small and tend to be host-specific (a species will latch on caterpillar larvae, for example).
They are under-studied and include the smallest insect in the world, the fairy wasp Dicopomorpha echmepterygis, which is wingless and blind and measures about 0.127mm in length.
Prof Charles Godfray, who teaches Population Biology at the University of Oxford and has studied parasitic wasps throughout his career, said these wasps were very important as “natural pest control” or “biological control”.
When there was an outbreak of mealybugs in Africa that was decimating cassava, a critical crop, scientists researched the parasitic wasp that targeted the bugs. “These were introduced into Africa and it was hugely successful and the problem was reversed. That had immense economic and social benefits.”
Godfray said scientists were working to find the specific parasitic wasps that could tackle certain pest species, and that it was happening in the UK: “In tomato greenhouses in the UK it was discovered 15 or 20 years ago that one could boost the yields of tomatoes by bringing in bumblebees, but the problem when you do that is you can no longer use any insecticides in the greenhouse because it’ll kill the bees.
“Then you get a problem with whitefly. But now there are a number of commercial companies that produce the parasitic wasp which is particular to the whitefly, and that controls the issue without insecticide.”
And these are also on sale to the general public: “There are companies that sell parasitoids that will attack aphids, that will attack leaf miners as well as the whiteflies,” he said.
