| Links to the story | Key Stage 2 and 3 programmes of study | Possible learning outcomes | Big ideas |
| a good year for Holly Blues | the interdependence of organisms in an ecosystem KS3 Science | the numbers of Holly Blue butterflies in any season depends upon many factors, some abiotic, others biotic the size of the Holly Blue population is regulated by the parasitic wasp | being and becoming summer stories Harmony principles: Adaptation Interdependence |
The black line shows a 4 year cycle (19972001, 2001-2005) and later 6 year cycle in numbers (2005-2011) , going from very high (boom) to very low (bust).
The graph shows that when the butterfly numbers are high, the numbers of parasites are low. Likewise, when the parasite numbers are high, the numbers of butterflies are low.
This controls the number of butterflies (and parasites) found. The effects of food and weather will affect the total numbers found in any one season, but the regular cycles are caused by the interactions between the butterflies and the parasite.
The data in the chart are modified from Smith (2018) Time series analysis of Holly bull records in Yorkshire – uncovering a parasitoid. The Naturalist. 143 (1099), 166-173.
Technical details:
The counts of butterflies took place in Yorkshire between 1996-2004 and 2004-2017. This suggests the presence of a parasite living alongside the holly blues. The paper announces that the parasite (L. mycthemerus). We have no idea if this parasite is present in Trendlewood park, but it is quite widespread, so it is possible. The red lines of the graph are estimates of the possible numbers of the parasite assuming it is controlling the numbers of holly blues. These are based on similar examples of parasite-host interactions in other ecosystems.
See also:
Revels, R. (1994) The rise and fall of the Holly Blue. British Wildlife 4: 236-8.
Revels, R. (2006) More on the rise and fall of the Holly Blue. British Wildlife 17: 419-24.