Over the three years of this project, data has been collected on the resistance status of silverleaf whitefly, Bemisia tabaci (MEAM1) to registered insecticides. In response to emerging resistance to the IGR pyriproxyfen, a recommendation to restrict usage of this IPM-compatible product to a 30 day window was adopted for the 2017/18 cotton season. This usage window has remained in place for subsequent seasons and testing indicates that resistance levels have stabilised. This research has been submitted for publication in Austral Entomology and is currently under review.

In 2016 resistance to spirotetramat was detected at two localities in North Queensland. Subsequent research has focused on understanding the underlying genetics of this resistance, and is in preparation for publication. In the most recent season (2018/19) resistance to spirotetramat was found in Emerald, which is the first record in a cotton production region. In response, the IRMS has been changed to restrict the usage of this insecticide to a single use per field (except for fields treated for mealybug which require a double application as per label direction to be effective).

Resistance to acetamiprid was suspected in the Macintyre region near Goondiwindi after the first round of bioassay testing. Further testing couldn’t confirm resistance, suggesting an initial false positive result.

Over the duration of the project, baseline susceptibility testing of products entering the cotton marketplace for control of silverleaf whitefly has been completed. This includes buprofezin, acetamiprid, emamectin benzoate and afidopyropen. A manuscript documenting earlier testing of products including spirotetramat, cyantraniliprole and dinotefuran was published in Austral Entomology.

In response to the widespread outbreaks of silverleaf whitefly, particularly in the 2016/17 season, the project team has actively engaged in extension events facilitated by the CCA and CottonInfo. This has included the production of videos on both resistance monitoring and whitefly parasitism.

Interest in assessing whitefly parasitism has grown steadily over the course of the project and knowledge on how to assess parasitism was presented at workshops run by the CCA at Moree, Dalby and Griffith. Evaluation of the toxicity of newer products against Eretmocerus was undertaken, but further experiments are needed to confirm results before this research can be confidently extended to industry.

The widespread extension of whitefly management issues, including stickiness, resistance and parasitism means cotton agronomists are better informed on the threat whitefly poses and the critical role IPM will play going forward.