Natures Valley Conservation
The Brenton Blue butterfly.
Brenton Blue Butterfly
The Brenton Blue butterfly was rediscovered in Nature's Valley in 1977 a 119 years after first being discovered in the Knysna district.
A research programme at Nature's Valley has been initiated by the Nature's Valley Trust. The objectives of the research are to find methods to promote the growth of a large population of O. niobe's host plant at the Fynbos Reserve in Nature's Valley, where O. niobe used to fly. Part of the reserve has been burnt and cutting is taking place in the unburnt portion. The research is being conducted by the botany department of Rhodes University.
The establishment of a fynbos reserve in Nature's Valley primarily to create a habitat for the Brenton Blue Butterfly can be seen as a sterling effort in the preservation of the Brenton Blue butterfly.
This butterfly's survival is largely determined by the presence of the host plant, Indigofera erecta, which the larvae exclusively feed on.
There is reason to believe that a bitter-sweet symbiotic relationship exists between the Brenton Blue and one of the 28 species of ants found on the reserve. Being a member of the Lycaenid family of butterflies, they can only complete their life cycle in association with a particular ant species.
The larvae have special glands that secrete a substance both nutritious and enjoyable to the ants. The larvae also emit pheromones (scents) which mimic (copy) ant brood emissions.
These devices induce the ants to treat the larvae as part of their colony and provide them with protection from cold, fire and predators. Pupation usually takes place inside the ant nest.
Research by Dave Edge:
Specific habitatThe Brenton Blue Butterfly needs very specific habitat for its survival. It lives in the coastal fynbos in a high rainfall area on a southern facing slope near the sea. The butterfly caterpillars feed only on one plant - the Indigofera Erecta - that has a tiny salmon-pink flower.
Adult butterflies hatch out twice a year, in November and February and live for only 2-3 weeks. During 2003, the February brood yielded four times as many butterflies as the November 2002 brood, and four times as many eggs were laid. It is believed this was the result of vegetation management techniques that were implemented.
"I burned a section of the vegetation, but discovered quite by accident, that by cutting a path through the thick bracken, the host plant multiplied four times more than with the burning technique," Edge says.
Ants
An important observation has been the interaction between the butterfly larvae and nocturnal Camponotus Baynei ants.
"We were never quite sure what role the ant played," says Edge. "I set up an observation unit at home and discovered the caterpillar eats the roots of the food plant, but the ants dig holes that allow the caterpillar to get to the roots. In return they are rewarded with a secretion from on a honey gland on the caterpillar’s rear."
For the time being the future of one of the world's rarest butterflies appears secure.
"At the moment things look good," Edge says. "The population is steadily increasing."