Diflubenzuron Tolerance Associated with Monooxygenase Activity in Field Strain Larvae of the Australian Sheep Blowfly (Diptera: Calliphoridae)

Abstract

In vitro monooxygenase activity (aldrin epoxidation) in 19 field-collected strains of the Australian sheep blowfly Lucilia cuprina (Wiedemann) varied over a 46-fold range. Activities were significantly correlated with toxicological responses to diflubenzuron and diazinon. Relationships between activity and toxicological response were stronger at the LC95 than at the LC50. Toxicological responses to diflubenzuron and diazinon were significantly related, particularly at the LC95. The slope of diflubenzuron concentration-response lines decreased as enzyme activity increased, suggesting that the proportion of the larval population that can tolerate high rates of diflubenzuron increases with increasing mean enzyme levels. Tolerance levels to diflubenzuron among the field strains (relative to a reference susceptible strain) were up to 10-fold at LC50 and 56-fold at LC95. This tolerance appears to be provided, at least in part, by enhanced larval monooxygenase levels.

Age‐dependent response to insecticides and enzymatic variation in susceptible and resistant codling moth larvae

“…Insecticide resistance involving MFOs has been already recorded regarding both BPUs (Pimprikar and Georghiou, 1979;Ismail and Wright, 1992;Kotze et al, 1997) and pyrethroids (Liu et al, 1984;Campanhola and Plapp, 1989). Synergism with PBO and metabolization of 14 C deltamethrin also indicate the involvement of MFO in resistance of C. pomonella to the latter compound (Sauphanor et al, 1997).…”

Insecticide Resistance and Vector Control

“…The initial mechanisms that conferred resistance to insect growth regulators were oxidase-based (44). Resistance to ivermectins has resulted from a number of factors, including oxidase, conjugation, and altered target-site mechanisms (45).…”

Thein vitroresponse of field strains of sheep blowfliesLucilia sericataandL. cuprina(Calliphoridae) in New Zealand to dicyclanil and triflumuron

“…Given the more restricted applicability of dicyclanil it could be expected that it would exert a lesser selection pressure than would triflumuron. Furthermore, resistance to triflumuron would likely have been potentiated by many years of prior use of organophosphate formulations (Kotze et al 1997;Haack et al 1999).…”

“…Individuals of L. cuprina that entered New Zealand from Australia carried alleles that conferred resistance against diazinon, an organophosphate insecticide (Wilson and Heath 1994;Wilson et al 2001). Later, some populations of L. cuprina in both Australia and New Zealand showed reduced susceptibility to a new active ingredient in dips, the benzoyl ureas, and L. sericata demonstrated more widespread organophosphate resistance than previously (Kotze et al 1997;Haack et al 1999;Wilson 1999). Weak side-resistance to other organophosphates was detectable and the degree of resistance to diflubenzuron, a benzoyl urea, was positively correlated with diazinon resistance (Kotze and Sales 1994;Haack et al 1999).…”