Identification of possible control options for a pest causing significant harm to kūmara crops is the focus of a new A Lighter Touch project with Vegetables New Zealand.
The Black field cricket is having an economically significant impact on vegetable crops, especially kūmara, and pasture in northern New Zealand, particularly Northland. All life stages of the cricket feeds on kūmara tubers underground, resulting in damage which can lead to crop losses of $10,000 to $30,000 per hectare depending on market pricing.
A Black field cricket on a kūmara tuber, showing the damage the pest causes to this crop. Credit Plant and Food Research.
Damage caused by the cricket feeding also results in significantly reduced crop yields in other vegetable crops and poor pasture growth. While complete crop loss is rare, in some cases entire fields can be rendered practically worthless due to feeding damage.
Black field cricket control options are limited and consequently the risk of resistance development is high. Current cricket control options include seasonal applications of synthetic pyrethroid insecticide sprays, and use of insecticide-treated grain baits. While the grain baits provide good control of Black field crickets particularly in pasture surrounding kūmara planting, kūmara growers have found the baits are not effective for complete control and prefer to use the insecticide spray option as the main in-crop control.
The preference for use of a single mode of action insecticide brings the threat of resistance, and the long-term sustainability of continuing to rely on it for control are a growing concern for kūmara growers. The use of targeted insecticide applications will become increasingly important to reduce the risk of resistance developing, and the sector is keen to find softer chemistry options that target specific Black field cricket life stages.
Black field cricket, Teleogryllus commodus. Credit Plant and Food Research.
The A Lighter Touch and Vegetables New Zealand funded project will involve a comprehensive review of all available information relating to the life cycle of the Black field cricket as well as what is known about monitoring and management of the pest, particularly in kūmara. This knowledge review will help to identify possible control options, or gaps in knowledge required to be filled in order to develop control options for Black field crickets.
Following the knowledge review, an assessment will be carried out to determine what further work would be required to develop a sustainable integrated pest management system for growing kūmara in New Zealand.
Find out more about this project in the Our Projects section of our website.
