Developing an Ecotoxicological Testing Standard for Predatory Mites in Australia: Acute and Sublethal Effects of Fungicides on <I>Euseius victoriensis</I> and <I>Galendromus occidentalis</I> (Acarina: Phytoseiidae)

Abstract

Laboratory bioassays for testing the effect of agrochemicals on Euseius victotiensis (Womersley) and Galendromus occidentalis (Nesbitt) on detached leaves of Glycine max (L.) (soybean) and Phaseolus vulgaris L. (French bean) were developed. The tests allowed standardized comparisons between mite species and leaf substrates, under "worst-case scenario" exposure, comparable with commercial pesticide application. Young juveniles, along with their initial food and the entire water supply, were sprayed to the point of runoff by using a Potter spray tower. The highest registered field rate concentration used on French bean was adjusted to deliver the same pesticide dose per higher runoff point spray volume on soybean. Cumulative mortality was assessed at 48 h, 4 d, and 7 d after spray application. Fecundity was assessed for 7 d from the onset of egg lay. Boscalid (Filan 500 WG), dithianon (Delan 700 WG), and kresoxim-methyl (Stroby 500 WG) caused no significant 7-d mortality or fecundity reduction to G. occidentalis or E. victoriensis compared with controls, and are classified as harmless to both species. Mancozeb (Mancozeb 750 WG) was highly toxic to both species, resulting in severe mortality and fecundity reduction and is considered incompatible with integrated pest management programs that use these species. Metiram (Polyram 700 WG) was highly toxic to E. victoriensis but only moderately toxic to G. occidentalis. Analyses of mortality proportions, including, and excluding unaccounted escapees, produced the same results. Test standardization on leaf substrates provides an alternative approach to standardization via residue on glass used by International Organisation for Biological and Integrated Control or Noxious Animals and Plants/West Palaearctic Regional Section regulatory testing in the European Union.

Toxicity of six novel fungicides and sulphur to Galendromus occidentalis (Acari: Phytoseiidae)

“…Concentrations in the laboratory based on the application of 600 l/ha b No significant differences between treatments, based on ANOVA performed on arcsine-transformed data c Means within columns followed by the same letter are not significantly different, based on Tukey-Kramer test performed on arcsine-transformed data (P [ 0.05) Boscalid is a carboxamide which inhibits succinate ubiquinone reductase (also known as complex II) in the mitochondrial electron transport chain. Our results confirm the results of Bernard et al (2004), who reported that boscalid had caused no significant mortality or fecundity reduction to G. occidentalis in a 'worst case scenario' laboratory study in Australia. Laurin and Bostanian (2007) also reported that boscalid residues were innocuous to adult A. baccarum.…”

“…Strobilurins inhibit ubiquinol oxidase at the Qo site, also known as complex III, in the mitochondria during respiration. They have been reported to be innocuous to predacious mites (Alston and Thomson 2004;Bernard et al 2004;Laurin and Bostanian 2007).…”

Free-living mesostigmatic mites in Australia: their roles in biological control and bioindication

“…Laboratory cultures of the mite are used to determine the effect of common pesticides on adult and juvenile mortality, as well as population growth rates. Ecotoxicological testing standards for agrochemicals are also being developed using phytoseiid mites in Australia (Bernard et al 2004).…”