Field assessment of attractants to improve the efficacy of RATTOFF® sachets for control of rats in sugarcane

The Australian sugarcane industry incurs significant crop loss from damage caused by rodents including Rattus sordidus and Melomys burtoni. In 2023, grower surveys around Ingham in Queensland indicated losses from rat damage were valued at $19 million, over a 54,500-ha area with similar losses in other regions. In 2023, an aerial-distribution emergency-use permit was approved for RATTOFF® use in ratooning sugarcane (PER94189). We tested whether uptake of RATTOFF® could be further enhanced by the addition of attractant coatings on the outside of sachets. A blind field study was conducted in five cane fields in the Ingham region. Four attractants were tested against the untreated control. Sugar Research Australia identified 200 active ground rat holes on the five sugarcane fields and used a randomised placement pattern to position one of each of the labelled sachets around each active rat hole in a 2.4 m (approximate) circle about 1.4 m apart. Results from observed bait-acceptance activity indicate that three of the putative coatings increased visitation and opening of sachets compared with the control or the fourth attractant. Camera monitoring of 33 sites confirmed sachets being attractive to birds but showed no other lethal non-target activity on the sachets. The data will support an application to modify the RATTOFF® formulation to include an external attractant coating.