The Museum’s Sensational Butterflies exhibition is host to over 500 butterflies each year. Each morning, work in the Museum’s butterfly house starts two hours before the exhibition opens because it takes constant attention to maintain the ideal environment for these butterflies to flourish. One of the aspects that needs to be attended to is pest control.
One of the most significant pests that needs to be kept under control in the butterfly house are Aphids.
Aphids are small sap sucking insects that are capable of rapid increase in numbers by asexual reproduction. If kept unchecked Aphids can rapidly destroy the plants needed to nourish the caterpillars and butterflies and so will affect the number of butterflies that can flourish. A way to naturally keep the number of aphids in check is to use parasitic wasps that are the aphids’ natural enemy.
In the Butterfly House, two species of Braconid wasps are used: Aphidius colemani and Aphidius ervi. Female Aphidius wasps lay single eggs inside immature aphids, which are then consumed from the inside by the larva.
As the larva matures the aphid is killed: the larva then pupates within the aphid, which swells into a characteristic round ‘mummy’, out of which the adult wasp finally cuts its way, leaving a large emergence hole.
Butterflies and moths also have parasitoids…
While the use of some parasitoid wasps can be beneficial for the butterflies to flourish, butterflies and moths also have their own miniature nemeses. The Anastatus colemani parasitoid wasp lays its eggs in Atlas moth eggs. The wasp larvae hatch and eat their way out, killing their host before it can grow into one of the largest insects on the planet.
The large cabbage white (Pieris brassicae), for instance, is attacked by tiny Chalcid wasps from the family Trichogrammatidae, Trichogramma brassicae. The wasps exploit the butterfly’s chemical communication.
During mating, the male butterflies pass on to females a pheromone which makes them unattractive to other males. The Trichogramma brassicae wasps are attracted to this pheromone and attach to the freshly mated female butterfly, which unknowingly carry them around until they stop to lay their eggs – which the wasps then promptly parasitise. The food of cabbage white larvae includes many crops, and the Trichogrammatid wasps are used to control them.
Other Chalcid wasps lay their eggs in caterpillars. Some species such as Copidosoma floridanum, in the family Encyrtidae, lay just one egg that divides repeatedly to give rise to up to 2,000 wasp larvae – a phenomenon called polyembryony. Some of the larvae hatch early and kill other parasitoids inside the caterpillar – these ‘soldier larvae’ have especially large mandibles and never mature into adults.
Thank you for helping us to learn more about our Sensational Parasitoids
The Digital Collection Programme is on a mission to digitise 80 million specimens from one of the world’s most important natural history collections. We are giving online access to the specimens and data through our Data Portal so that citizen scientists, researchers and data analysts from all over the world can access it.
We have imaged the Museum’s collection of microscopic Chalcids and these have already been transcribed by members of the public.
With your help, the data and information contained in the labels on these slides is being made available to scientists worldwide, who can study these creatures further and add to our arsenal of natural pests to improve sustainable agriculture and address the impacts of climate change.