title: Estimating Densities of the Pest Halotydeus destructor (Acari: Penthaleidae) in Canola.
abstract: Development of sampling techniques to effectively estimate invertebrate densities in the field is essential for effective implementation of pest control programs, particularly when making informed spray decisions around economic thresholds. In this article, we investigated the influence of several factors to devise a sampling strategy to estimate Halotydeus destructor Tucker densities in a canola paddock. Direct visual counts were found to be the most suitable approach for estimating mite numbers, with higher densities detected than the vacuum sampling method. Visual assessments were impacted by the operator, sampling date, and time of day. However, with the exception of operator (more experienced operator detected higher numbers of mites), no obvious trends were detected. No patterns were found between H. destructor numbers and ambient temperature, relative humidity, wind speed, cloud cover, or soil surface conditions, indicating that these factors may not be of high importance when sampling mites during autumn and winter months. We show further support for an aggregated distribution of H. destructor within paddocks, indicating that a stratified random sampling program is likely to be most appropriate. Together, these findings provide important guidelines for Australian growers around the ability to effectively and accurately estimate H. destructor densities.
authors.affiliation: Department of Zoology, Bio21 Institute, The University of Melbourne, Parkville, VIC 3010, Australia. astonarthur@bigpond.com.
authors.forename: Aston L
authors.initials: AL
authors.lastname: Arthur
authors.affiliation: Department of Zoology, Bio21 Institute, The University of Melbourne, Parkville, VIC 3010, Australia. Department of Genetics, Bio21 Institute, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Ary A
authors.initials: AA
authors.lastname: Hoffmann
authors.affiliation: Department of Zoology, Bio21 Institute, The University of Melbourne, Parkville, VIC 3010, Australia. Cesar, 293 Royal Parade, Parkville, VIC 3052, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Umina
mesh_terms: D000818:Animals; D029741:Brassica rapa; D000069601:Crop Protection / Q000379:methods*; D008925:Mites; D011156:Population Density; D012987:Soil / Q000469:parasitology*
chemical_list: D012987:Soil
keywords: Halotydeus destructor; pest density; sample size; sampling technique; visual sampling