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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The activities of two important groups of detoxifying enzymes, the glutathione S-transferases and the mixed-function oxidases, were assayed throughout the lifetimes of worker honey bees (Apis mellifera L.). Detoxification capacity decreased on a per insect basis in older workers and was associated with a dramatic loss of midgut protein. However, analysis of specific activity (enzyme activity per milligram protein) showed increasing activity levels as bees aged and began to forage. These results show that foraging worker honey bees compensate for protein loss by increasing the activity of important enzymes, suggesting a possible biochemical adaptation for foraging in contaminated ecosystems.

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