The effect of landscape- and local-scale non-crop vegetation on arthropod pests and predators in vineyards

Abstract

Experiments were conducted to assess any influence of the landscape and local (‘field’ scale) non-crop vegetation on conservation biological control (CBC) via predation of insect pest eggs in vineyards. In the 19th Century, world industry including agriculture was based on coal. In the 20th Century, oil was the main energy source while many believe that this century, a bio-economy will become the norm. This not only applies to energy sources but to new and more sustainable ways of growing the world’s food and beverages. For example, the United Nations has produced a number of strategic reports on this topic, including the work of de Schutter (2010) http://www.unep.org/publications/ebooks/foresightreport/Portals/24175/pdfs/Foresigh t_Report-21_Issues_for_the_21st_Century.pdf. In this, it was strongly suggested that agro-ecology is the only way of feeding the human population of nine billion, which is expected in a few decades. De Schutter suggested that in developing countries, yields can double in one decade if this system were to be adopted. In ‘developed’ countries, the same conclusion applied although the absence of the appropriate government policies is currently restraining this approach. Vineyards worldwide are aspiring to a more sustainable approach to viticulture and a current worldwide surplus is accelerating moves in that direction, including the conversion of some vineyards to organic viticulture. A key driver for these changes is the need to reduce variable costs in vineyards (pesticide, herbicide, fungicide, fuel and labour). However, wine growers are largely bereft of appropriate and topical advice to help them in this. Although some specific pest-management protocols do exist (e.g., the deployment of flowering buckwheat; F. esculentum between vines to provide nectar for beneficial insects), little attention has been paid to whether or not these local, within-vineyard practices are the most appropriate way of enhancing ecosystem services (ES) such as insect biological control. This thesis, therefore, addresses a wider, landscape scale and investigates whether landscape features outside the vineyard itself influence the numbers and phenology of invertebrate pests, and predators and their predation efficacy. To investigate this, geographic information systems (GIS) were used to examine the relationship between the landscape of the Waipara Valley, New Zealand, in relation to the above variables. Invertebrate trapping was carried out but to address more accurately the dynamics of the system, surrogate prey comprising eggs of the light brown apple moth, E. postvittana and the tomato/corn ear/boll worm, H. zea were used in 25 vineyards. Egg disappearance rates were assessed by ‘before and after’ counts, usually after 24 hours and by infrared illuminated digital, movement-sensitive video. It was concluded that, in fact, there were few landscape effects on these measurements. Subsequent within-vineyard manipulation of the between-row flora, using herbicides, showed that such simple management techniques involving leaving some ‘weeds’ between the vine rows had a substantial effect on pest predation rate. This latter result means that viticulturalists who aspire to a non-monoculture vineyard have a readily available service-providing unit (SPU) at their disposal at low cost. This work also strongly supports the aspirations of the United Nations, among other international bodies, for farming to move towards being part of a bio-economy.