One of three levels (O, 1, 10 mg·liter-1) of the cytokinin-active substituted phenylurea compound CPPU was applied with or without 100 mg GA/liter to developing clusters of `Sovereign Coronation' and Summerland Selection 495 grapes (Vitis spp.). In a similar experiment, one of three levels (0, 1, 10 mg·liter-) of either CPPU or the related compound thidiazuron was applied to `Simone' and Summerland Selection 535. Both phenylurea chemicals tended to linearly increase cluster weight and berry weight while reducing degrees Brix, pH, and anthocyanins and increasing titratable acidity. A subsequent trial with O, 4, and 8 mg thidiazuron/liter on all four varieties yielded similar results. GA had no individual or synergistic effects. Due to the very low concentrations required, CPPU and thidiazuron show great promise as chemical tools for the increase of berry weight in seedless table grapes. Chemical names used: N-(2-chloro-4-pyridyl) -N'-phenylurea (CPPU); N1-phenyl-N'-l,2,3-thiadiazol-5-yl urea (thidiazuron);

Possible reasons reported in D. melanogaster studies where resistance did not occur after insecticide selection included avoidance and associated microbial complexes. The low level of malathion resistance observed in the selected SWD populations and a field-collected population is useful information in the development of insecticide resistance management programmes. © 2016 Her Majesty the Queen in Right of Canada Pest Management Science © 2016 Society of Chemical Industry.

Populations of obliquebanded leafroller, Choristoneura rosaceana (Harris), were collected from organic and conventionally managed orchards located in the Okanagan and Similkameen Valleys of British Columbia Neonate F1 progeny were assayed for resistance to azinphosmethyl, tebufenozide, methoxyfenozide, and indoxacarb using a leaf disk bioassay. Significant differences in resistance levels among populations were observed for all four insecticides. Insects collected from organic sites were more susceptible to all insecticides than were insects collected from conventional sites. Resistance to the benzoylhydrazine insect growth regulators tebufenozide and methoxyfenozide was highly correlated with resistance to azinphosmethyl across populations, indicating cross-resistance between these compounds. The highest levels of resistance were observed with indoxacarb, but resistance levels to indoxacarb did not correlate with those for azinphosmethyl. Dose-response regression lines for tebufenozide were parallel across populations, suggesting that the resistance mechanism(s) were quantitatively, but not qualitatively, different. Cross-resistance between azinphosmethyl and benzoylhydrazine insecticides indicates that a resistance management strategy for obliquebanded leafroller involving the rotation of these materials is not likely to be successful.

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