This project has focused on two previously untested methods for managing and monitoring fruit fly in vegetable crops; Netting and repellents, and attraction with UV light.

Floating row covers were both a visual and physical barrier. Netting that was draped over crops and secured with soil effectively excluded fruit flies from capsicum and chilli crops. Even though the large mesh size of Vent Net allowed flies to crawl through, this material still significantly reduced entry of flies into the crop, cutting fruit infestation by 98%. Aphid Net reduced infestation by 99% but other pests inside the crop increased. VegeNet proved both lightweight and effective at blocking flies. No infested fruit was found under this material while it remained intact and sealed to the ground.

Floating row covers improved yield and quality of capsicum fruit. Netting increased marketable yield by 10 to 80%, while the number of fruit scored as grade 1 increased by 24 to 55%. The biggest gains were observed for crop covered by 18gsm fleece, where the number of grade 1 fruit was more than doubled. Unfortunately this single-use material proved relatively fragile, so is unlikely to provide good protection from fruit flies.

These effects were not repeated with chillies. Yield and quality of chilli crops in Sydney and Bundaberg were unaffected by various netting materials, even though the plants were larger and appeared healthier.

Field trials also tested Surround® kaolin clay applied to chilli plants. Despite issues with application and permanence after rain, no infested fruit were found on Surround® treated plants. This promising result deserves further examination in a more commercial setting. Laboratory and field cage trials examined the attractiveness of white, green and UV light. Green light was attractive during the day, while white light was repellent. UV light was most attractive at dusk, when flies are mating, and captured equal numbers of male and female flies in field cage tests. Trials in a large net house demonstrated that a UV light placed against a dark background was extremely attractive to flies. However, the same light in the open was not attractive, and even repellent. A small field trial was conducted using a prototype UV light trap. The number of flies captured on yellow sticky traps was doubled in the presence of the UV light, with more females captured than males.

A combination of UV light with another attractant, such as protein bait or odour lure, could provide better results than either method used alone. However, it will be important to clarify how to locate any such device for best effect.

Outputs from the project include a series of five x three minute videos for growers. These detail the fruit fly lifecycle, monitoring, protein baiting, use of MAT and female traps, and finally barriers and hygiene.

The video material is expanded in greater detail in an accompanying 32pp A4 booklet; “Fruit fly management for vegetable growers”. For the first time, this booklet brings existing information and knowledge about fruit flies into a single resource, and presents it in a form suitable for growers to use.

This project has been funded by Hort Innovation, using the research and development levies listed below and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

• Vegetable Fund