Abstracts Category : Other

Integrated management of ground wt (Orthoptera: Anostostomatidae) in Marlborough vineyards

by Jerry Asalma Nboyine

The intensification of agriculture has led to monocultures of high-yielding plant species/cultivars over large areas of land. This provides abundant resources for insects which feed on those monocultural species, elevating them to the status of econmic pests. In the Marlborough region, New Zealand, the conversion of native vegetation in the Awatere Valley to pastures, and in the last 30 years to vineyards, has elevated an endemic orthopteran insect, referred to as wt (Anostostomatidae) in Maori language, to occasional pest status. This wt damages vine buds at budburst, consequently reducing yields. Damage is currently managed by tying plastic sleeves around the trunks of vines (Vitis vinifera L.); the sleeves are slippery and deny wt access to buds. This management approach was adopted, instead of using pesticides, because of the significance of wt in Maori culture and threats to populations of some wt species. However, this management technique is labour intensive and costly, and sleeves often need to be repaired/replaced, leading to further costs. They also litter the environment when they become detached from the vines. Hence, this PhD work aimed at developing an ecologically-based integrated management strategy for wt based on an understanding of the biology and ecology of the species associated with vine damage. A range of laboratory and field experiments were conducted to 1) confirm the identities and number of wt species damaging vines, 2) wt biology, densities and distribution in vine and non-vine habitats, 3) the range of plant species in wt diet, 4) habitat manipulation strategies to mitigate wt damage and 5) strategies to deter this insect from vineyards. A phylogenetic analysis of sequences obtained from wt collected from vineyards confirmed that a single species was associated with bud damage. It was identified as Hemiandrus sp. promontorius (Johns 2001) using morphological keys. This species is not threatened but has a restricted habitat range. It laid a mean of 55 eggs between March and May, and these hatched after five months. The sex ratio of this wt was unity. Of three habitats searched, higher numbers of this insect per square meter were found in vines than in either pastures or shrublands. Within vineyards, they were mostly found inhabiting burrows in the bare, moist and less compact soil under vines, with few wt occupying burrows in the inter-row. A high throughput analysis of DNA sequences from faecal pellets of wt collected from vineyards showed that this insect feeds on plants from 30 families and 44 genera. Although vines and grasses were the dominant plants in the viticultural landscape studied, dicotyledonous weeds were found to be important components of wt diet. In terms of management, three under-vine treatments [pea straw mulch (Pisum sativum L.), mussel shells (Perna canaliculus Gmelin, 1791), tick beans (Vicia faba Linn. var. minor (Fab.))] and two inter-row treatments [exisitng ryegrass-dominant vegetation, tick beans] were tested for their efficacyAdvisors/Committee Members: Wratten, Steve.