Laboratory bioassays of new synthetic and microbial insecticides to control Eucalyptus tortoise beetle <i>Paropsis charybdis</i>

Abstract

Paropsis charybdis or eucalyptus tortoise beetle is (one of) the most significant pests of eucalypts in New Zealand It severely defoliates Eucalyptus nitens and Eucalyptus globulus plantations leaving heavilydamaged trees with reduced growth and poor form Laboratory bioassays of new synthetic and microbial insecticides were undertaken to identify management options compatible with biological control The current insecticide used for operational control alphacypermethrin was a positive control Of the products tested spinetoram (Sparta) gave the most promising results (100 mortality after 14 days) for control of adult P charybdis Spinetoram and spinosad (Success Naturalyte) the microbial control agents Beauveria bassiana (F305 ex Botanigard) and Bacillus thuringiensis var tenebrionis and the enterobacterium Yersinia entomophaga all resulted in high mortality of larval P charybdis after 4 days Targeting larvae alone may not be economically viable leaving spinetoram as the only possible additional insecticide for managing P charybdis Potential barriers of cost application and nontarget impacts are yet to be addressed