Developmental Host-Specificity of Mozena obtusa (Heteroptera: Coreidae), a Potential Biocontrol Agent for Prosopis Species (Mesquite) in Australia

Mozena obtusa Uhler (Heteroptera: Coreidae) was examined in quarantine for its potential as a biological control agent of Prosopis species (mesquite) in Australia. Trials were conducted on 16 nontarget plant species to estimate its developmental host range. Complete development occurred on all Prosopis species that have become naturalized in Australia as well as on four Australian native species (Neptunia species and Paraserianthes lophantha), although reproductive diapause prevented assessment of subsequent fecundity. Development through the first feeding nymphal instar also occurred on other plant species representing two subfamilies. Nymphal performance was highly variable on both target and nontarget species, possibly because variation in plant nitrogen composition affected plant quality. The correlation between environment, plant nitrogen, and plant quality is likely to be sufficiently strong to determine whether a plant species can support development. Plant quality should therefore be considered when predicting the field host range of M. obtusa and of sap-sucking coreids generally. Nonetheless, our preliminary results suggest that M. obtusa may not be sufficiently specific for release in Australia, although insufficient understanding of its oviposition behavior in the field and the effect of plant quality on development means that its rejection would be premature.