This article was prepared by postgraduate student Hannah Lewis as part of the ECOL 608 Research Methods in Ecology course.
Most of us enjoy the sight of a butterfly flitting around our backyard, however many of us will not be aware of the importance of native butterflies in agricultural ecosystems and the plight that they are facing. Could you name even 3 types of native New Zealand butterflies? The monarch butterfly which is native to North America seems to be the most well known representative of butterfly species within New Zealand.
The intensification of modern agriculture has resulted in an increase in food production to meet the requirements of a growing worldwide population. The amount of cereals (wheat, barley, oats etc) coming off an area of land has increased from 3800 kg/ha in 1968 to 8000 kg/ha 2008. A major issue with intensification has been the reduction of suitable habitat for butterflies and other insect species and the development of plant monocultures. Monoculture (photo 1) is the continuous planting of the same crop over a large area. Doing this greatly decreases the amount of places that are suitable for insects and butterflies to nest/lay eggs and live in. Insects are our main plant pollinators, without this essential function that they provide us for free, there would be no food to feed the world.
Mark Gillespie of Lincoln University studied his PhD on the prevalence of butterflies in vineyards in the Waipara region, North Canterbury. The intensification of agriculture is one of the main drivers behind biodiversity loss. The introduction of agrochemicals and the creation of homogenous fields (monocultures) without hedgerows or shelter belts have modified natural habitats which have become unproductive for no other use than intensive agriculture and food production.
The analysis of six different vineyards partaking in the Greening Waipara project (see link 2 for more detail) showed that the endemic common copper (Lycaena salustius) (photo 2) and endemic southern blue (Zizina oxleyi) (photo 3) were the most prevalent native butterfly species. Mark measured butterfly density by doing The results show that it is important to maintain remnant vegetation sites for butterflies to inhabit near cropping areas as these are not influenced by farm machinery and agrochemicals.
Mark’s thesis results showed that the Greening Waipara plantings were of least importance to butterflies although this could be because they are so young. Having only been planted within the past 7 years, the plantings are also fairly isolated from other bigger patches of favourable living conditions. Basically, butterflies require a very diverse conservation area to sustain a population including differences in vegetation and the landscape.
To increase the population of butterflies in their vineyard, landowners need to see economic benefits to them being there. Aside from their general conservation value, native butterflies have aesthetic and economic effects on tourism and marketing. Making them good money earners for the landowner, particularly in wineries where tourists will stop and visit and spend some time outdoors. Currently, the vineyards in the Waipara Region are poor habitats for native New Zealand butterflies. Butterflies are commonly used as an indicator species of a particular environment, that is the presence or absence of butterflies native or otherwise can indicate the state of the environment that is being searched. Hence an increase in native butterflies can indicate a healthier environment which is better for the sustainability of monocultures in New Zealand.