Australia: Small bug, big impact on pests in tomato crops

In 2014 Gawler River Tomatoes (Kapiris Bros.), located North of Adelaide/Australia were spraying up to twice a week for Whitefly control. Even with the diligent spray regime, the control achieved was minimal and by the time fruit was ready to harvest, a significant amount of sooty mould was present. Fast forward to 2016 and the number of Whitefly sprays has dropped to 2 per season and in some cases whitefly sprays aren’t needed at all. The big difference in the past 2 years has been the implementation of an IPM program under the guidance of Biological Services.

Nesidiocoris Adult feeding on a whitefly scale

At around 10 ha planted per year (both hydroponic and soil grown), the decision to switch the entire farm over to IPM was not one that was taken lightly. However this is one of the key reasons the program worked so well in the first season. “We have seen growers in the past try to implement an IPM program in only part of their farm while spraying conventionally in the rest. In these situations, the risk of chemical contamination is high and often causes the program to suffer. For this reason we’ve made the choice not to work with growers unless they would convert the whole farm” – Lachlan Chilman, Biological services.

The real hero of this story is a small predatory bug, Nesidiocoris tenuis, which Biological Services began to offer as part of their Tomato and Eggplant IPM Program in the summer of 2014. This efficient predator is used widely throughout Spain and has had a huge positive impact on the industry there. N. tenuis feeds on all stages of the whitefly but may also feed on caterpillar eggs, two-spotted mites and basically anything else small enough. These bugs are inoculated onto the tomato seedlings in the nursery, so when Gawler River Tomatoes receive their plants, young N.tenuis begin to hatch out within days. The voracious nature of N.tenuis can be a double edged sword, when their numbers get too high and the whitefly levels low, they may feed on the heads of the plants. Luckily they can be reduced as required with fairly soft sprays.

IPM team leader Stephanus Malherbe with Gawler River Tomatoes' Jimmy Kapris inspecting their insect numbers. The farm uses Nesidiocoris to control whitefly.

In addition to N.tenuis a number of other beneficials are included in the program. These include:

Encarsia formosa & Eretmocerous warrae – Both are parasites of whitefly scale.
Hypoaspis spp. – For the control of Fungus Gnats and Thrips larvae in the growing media.
Phytoseiulus persimilis – For the control of TSM, only released when necessary.

Head grower Andy Duong, couldn’t be happier with the results: “We’ve reduced our sprays by around 80%, we still have to do a few sprays for Russet Mite, and of course fungicides. The reduction in time spent spraying has allowed us to focus on other ways to improve our growing practices”. Some of these improvements include upgrading many growing houses to hydroponic systems, repairing screening on structures to keep out pests and controlling weeds more thoroughly. These seemingly small acts of improving screening and keeping on top of the weeds are both huge aspects of an IPM program and should not be overlooked. These have greatly attributed to the reduction of sprays and improvement in fruit quality along with the introduction of beneficial insects of course.

Biological Services provides alternatives to regular broad spectrum insecticide programs in a range of horticultural crops, and have staff to provide the technical backup and support to enable growers to effectively manage IPM programs on their properties. A key problem at present is insecticide resistance to many major pests such as mites, aphids, whiteflies and thrips. Biocontrol and IPM programs are intelligent options to protect crops and reduce pesticide applications.

For more information:
Biological Services
www.biologicalservices.com.au