Stem injection of a systemic insecticide to control Uraba lugens on urban Lophostemon confertus trees.

Background: Uraba lugens Walker (Lepidoptera: Nolidae) has the potential to become a serious pest of susceptible forestry and urban trees in New Zealand. Stem injection of insecticides provides a method for the control of U. lugens in public locations where foliar applications are not suitable. Field and laboratory studies were conducted in 2009 and 2010 to determine a dose response profile of U. lugens larvae to acephate injected at 0.0, 0.25, 0.50 and 1.00 g cm(-1) tree diameter measured at breast height (dbh). The concentration of the injected solution varied across years.

Results: The highest mortality (85-100%) of U. lugens larvae occurred at 1.00 g acephate injected cm(-1) dbh. The lower rates (0.25 and 0.50 g acephate cm(-1) ) were more effective in 2010 than in 2009, a factor attributed to the change in volume of injected solution.

Conclusion: Systemic injections of acephate at rates above 0.50 g cm(-1) dbh provide a tool for the management of U. lugens in public places. It is recommended that stem injection operations for control of U. lugens larvae be timed to coincide with the emergence of first instars so that larvae are exposed to lethal insecticide doses.