In order to keep you updated with entomology activities, the following article outlines the research trials to be conducted on mirids this season on the Darling Downs by Dr Moazzem Khan (Senior Entomologist, DEEDI, Toowoomba).
Mirids have become regular pests of Bollgard® II cotton. Despite the development of good crop-stage thresholds and IPM options for mirids, more research is needed to further improve mirid management in cotton.
Green mirid adult Green mirid nymph
Development of plant based thresholds
The aim of this trial is to determine the amount of fruit loss that occurs per mirid/day. and continues work from last season. Results from this trial will be incorporated into existing thresholds and will help growers and consultants to determine a threshold appropriate for specific fields given mirid activity and plant response.
The trials will be conducted at Nandi, Macalister and Jandowae with each site having 3 treatments. These treatments will be 1) unsprayed, 2) sprayed and 3) commercial (farmers management) resulting in different levels of mirid activity and damage.
Impact of mirid management on predators and parasitoids of whitefly
Management of mirids with broad-spectrum insecticides can lead to flaring of whitefly populations.
The word flaring is commonly used in entomology and refers to a population outbreak or explosion.
Anecdotal evidence suggests that broad-spectrum chemicals kill parasitoids and predators that play an important role in keeping whitefly populations in check. In absence of their natural enemies whitefly population grow rapidly in favourable environmental conditions.
The objective of this trial is to gather hard data to test this hypothesis. This trial will be conducted in Macalister with three treatments to create different disruption level scenarios.
The treatments consist of:
1) Spray at threshold using integrated pest management (IPM) control options
2) Spray at threshold with disruptive control options
3) Spray at below threshold with disruptive control options.
Pheromone traps as monitoring and management tools
The objective of the trial is to evaluate mirid pheromone traps as a monitoring and management tool.
Six traps baited with pheromone will be set up in a 4 ha (400 x 100) field. An adjacent field, 500 m away without pheromone traps, will be used to compare mirid number and management.
For more information about these trials please contact the entomology team via the comments section of this blog posting.