Some ecological factors influencing the breeding success of the Brenton Blue butterfly, Orachrysops niobe (Trimen)(Lepidoptera: Lycaenidae)

Published source details Edge D. (2002) Some ecological factors influencing the breeding success of the Brenton Blue butterfly, Orachrysops niobe (Trimen)(Lepidoptera: Lycaenidae). Koedoe, 45, 19-34.
Share Tweet Email

Actions

This study is summarised as evidence for the following.

	Action	Category
	Remove or control non-native or problematic plants Action Link
	Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats Action Link

Remove or control non-native or problematic plants

A site comparison study in 2000–2002 in one shrubland site in the Western Cape province, South Africa (Edge 2002) reported that after prescribed burning there were fewer Brenton blue butterfly Orachrysops niobe eggs in an area where bracken fern Pteridium aquilinium was removed compared to where it was not removed. In an area that had been burned, there were fewer Brenton blue eggs/Indigofera erecta host plant in the section with bracken fern control (November 2001: 0.035 eggs/100 plants; January–February 2002: 0.38 eggs/100 plants) than in the area with no control (November 2001: 0.32 eggs/100 plants; January–February 2002: 0.81 eggs/100 plants). Results were not tested for statistical significance. In September 2000, a 2,700 m² area of reserve was burned. Prior to the burn, in over 1,000 m² of the area bracken fern was cut and 0.2 m of topsoil was turned over (“skoffeled”). In that area and another 1,400 m², natural succession was allowed after the burn. In another 300 m²of the burned area, bracken fern was removed manually for 6 months after the burn. In a 1,500 m² area of reserve that was not burned, paths were cut with shears in July 2001, avoiding trees, large bushes and Indigofera erecta plants, and thereafter new bracken ferns were removed manually. In November 2001 and January–March 2002, all Indigofera erecta plants identified in the burned and unburned areas were checked for eggs and larvae.

(Summarised by: Eleanor Bladon)
Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats

A site comparison study in 2000–2002 in one shrubland site in the Western Cape province, South Africa (Edge 2002) reported that after prescribed burning and some management of bracken fern Pteridium aquilinium there were fewer Brenton blue butterfly Orachrysops niobe eggs and adults during the laying and flight season in areas that had been burned. There were fewer Brenton blue eggs found in areas that had been burned (0.4–1.3 eggs/100 m²) than unburned areas (14.3–70.0 eggs/100 m²). Additionally, fewer adult males (November: 69%, February: 31.1%) and females (November: 22.2%, February: 10.6%) were found in the burned areas (64% of the area surveyed) compared to unburned areas (males November: 31.0%, February: 68.9%; females November: 77.8%, February: 89.4%). In September 2000, a 2,700 m² area of reserve was burned. Prior to the burn, in over 1,000 m² of the area bracken fern was cut and 0.2 m of topsoil was turned over (“skoffeled”). In that area and another 1,400 m², natural succession was allowed after the burn. In another 300 m² of the burned area, bracken fern was removed manually for 6 months after the burn. In a 1,500 m² area of reserve that was not burned, paths were cut with shears in July 2001, avoiding trees, large bushes and Indigofera erecta plants, and thereafter new bracken ferns were removed manually. In November 2001 and January–February 2002, all Indigofera erecta plants identified in the burned and unburned areas were checked for eggs and larvae. In October–November 2001 and January–February 2002 walking transects (9 times/season) and fixed-point surveys (7–8 times/season) were conducted to count and sex adult butterflies (it is not specified how many were in the burned and unburned areas).

(Summarised by: Eleanor Bladon)