Spatial analysis of a gall midge (Diptera: Cecidomyiidae) and its associated parasitic wasps (Hymenoptera) on Hebe stricta

Claas Damken *1, Jacqueline Beggs 2, George Perry 1

1 School of Environment, The University of Auckland, Private Bag 92019, Auckland, New Zealand
2 School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand

Climate change and landscape fragmentation are two major threats for global terrestrial biodiversity. In particular, habitat size, habitat quality and isolation are influenced by climate change and landscape fragmentation. Within the concept of meta-population biology, the survival of species in fragmented landscapes is mainly due to these three environmental factors. To cope with rising temperatures, stenotherm species such as mobile insects may migrate to higher and therefore cooler regions. However, at increasing altitudes, habitat quality can change or the host plant might still be restricted to lower altitudes. While these spatial and temporal “bottlenecks” are already a problem for monophagous insects, species of higher trophic levels are even more vulnerable to these spatial shifts. For example, parasitic wasps have to rely on both the respective host insect and its host plant.  This project investigates whether changes in population dynamics along an altitudinal gradient will result in increased species requirements of habitat quality and habitat size in a tritrophic system. Within the Tongariro National Park, spatial distribution of broad-leaved Koromiko clusters (mainly Hebe stricta), habitat quality and the abundance of bud galls caused by a hitherto undiscribed gall midge (Diptera: Cecidomyiidae), were mapped on a local scale along a mountain stream in two consecutive years (2010 & 2011). Hymenoptera were reared from galls collected in 2011. First findings of the spatial pattern of parasitic wasps associated with the gall midge are presented.

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