Evaluation of insecticides for western flower thrips resistance
The world’s leading thrips expert, Dr Laurence Mound (CSIRO Entomology), said simply, “it (WFT) will send Australian growers to the wall”. Since their discovery in Australia in 1993 WFT have continued a relentless push into every Australian State causing severe crop losses in a range of industries. HG03003 aimed to deliver on going effective chemical management of western flower thrips (WFT) by providing crop specific resistance monitoring and the identification of novel and new chemicals. Field trials on newer chemistries identified two insecticides: acetamiprid and thiamethoxam as efficacious alternatives to spinosad, but residue data is required on a crop specific basis to support their use against WFT. Spinosad is currently the only insecticide that can be used in an integrated pest management program (IPM) for control of WFT. Resistance monitoring has verified an earlier laboratory finding that spinosad resistance would increase and in 2005 further increases in spinosad resistance were detected in field populations. Spinosad resistance in WFT from lettuce was found to increase from 40 to 87 fold from 2005 to 2006 with resultant control problems. The loss of spinosad to resistance will jeopardise the entire WFT control strategy including IPM. If effective WFT IPM is to progress, then improved resistance management of strategic chemicals including spinosad is paramount.