Improved management of rutherglen bug in the Northern Region

Rutherglen bug (Nysius vinitor) (RGB) is a native Australian insect that causes occasional but significant damage to the grains industry, primarily due to impacts on yield and quality when infestation occurs during grain fill. Damage to seedlings is also observed in years when populations migrate from senescing winter crops to emerging summer crops. Impacted grain crops include sunflower, sorghum, canola and safflower. In years of significant populations, pulses and cereals may also be affected.

It is well known that migratory flights of RGB on storm fronts from inland Australia are one source of the pest. However, there are populations that persist in the local environment on weed and crop hosts which provide consistent pest pressure. When the timing of these two populations coincide, management is severely challenged.

A recent review indicated it is unlikely new chemistries will be brought to market with improved efficacy on RGB compared to the current options. Given this, it is important to understand when and how best to employ the limited options available.

There is existing knowledge on pest lifecycle development, habitat preference and environmental conditions that trigger flight patterns, however fundamental ecology work is still required to understand the environmental triggers for synchronised emergence of RGB within the Northern Region and then to understand how populations develop and disperse between native vegetation, alternative weed hosts and susceptible crops.

Coupling this understanding of pest population/environment dynamics with knowledge of the impact of different pest levels at critical growth stages will assist growers and agronomists to better manage the pest and only apply insecticides when an economic return is likely.

Sporadic pests such as rutherglen bug can cause significant economic losses and successful management is often challenged by failure to understand the risk of the pest occurring in any one season. Improved management of rutherglen bug will be achieved through research investigating:

• the drivers of rutherglen bug emergence, development and dispersal in the northern grains region
• critical pest thresholds for key crops and the development of robust and manageable sampling strategies
• efficacious control strategies
• opportunities to predict (in real-time) the likelihood of damaging RGB populations occurring during susceptible crop stages

This investment seeks to reduce the financial impact of Rutherglen bug by improving our understanding of the factors that enhance its persistence, developing a risk framework for predicting infestation and providing growers with knowledge on when it is economic to implement control options