A new species of gall midge (Diptera: Cecidomyiidae) feeding on ornamental Cordyline fruticosa(Asparagaceae) in Australia

Larvae of an undescribed gall midge were found feeding on leaves and stems within leaf sheaths and between leaf blades of potted plants of Cordyline fruticosa (Asparagaceae) in a production nursery in Queensland. The following varieties of the host plant were infested: Apple Blossom', Glauca', Kilauea', Negra', Pink Diamond, 'Purple Prince' and Willy's Gold'. The new species, Dasineura cordylineaeKolesik sp. nov., is described and its cytochrome oxidase unit I mitochondrial gene segment is sequenced. The new species is the first known gall midge feeding on a plant species of the genus Cordyline. Orange larvae induce oval shallow swellings on the leaf and stem tissue, which becomes necrotised during the later stage of larval feeding. Necrotic areas remain visible to the end of leaves' lives and decrease the market value of the plants. In the production nursery investigated, the lesions caused by the gall midge provided an entry for a fungal infection by Fusarium sp. inflicting further injury to plants. Larvae of the new species were preyed on by larvae of Gaurax sp. (Diptera: Chloropidae). This is the first worldwide record of Chloropidae preying on Cecidomyiidae.

The host specificity and climatic suitability of the gall fly Cecidochares connexa (Diptera: Tephritidae), a potential biological control agent for Chromolaena odorata (Asteraceae) in Australia

Host specificity tests on Gynaikothrips ficorum (Marchal) and Gynaikothrips uzeli (Zimmerman) (Thysanoptera: Phlaeothripidae) have shown that under experimental conditions, G. ficorum will induce leaf galls on both Ficus benjamina L. and Ficus microcarpa L. f. (Rosales: Moraceae), but G. uzeli will induce galls only on F. benjamina. A further interesting aspect of the results is that gall induction by G. uzeli on F. benjamina appears to have been suppressed in the presence of F. microcarpa plants in the same cage. Liothrips takahashii (Moulton) (Thysanoptera: Phlaeothripidae), an inquiline in the galls of these Gynaikothrips, is reported for the first time from Australia, mainland China, Malaysia, Costa Rica, and western USA.

Performance of Sirex noctilio’s biocontrol agent Deladenus siricidicola, in known and predicted hosts

Survival of the free-living mycetophagous form of Deladenus siricidicola, the major biological control agent of Sirex woodwasp, Sirex noctilio, was tested in known (Pinus taeda) and predicted novel (P. elliottii subsp. elliottii × P. caribaea var. hondurensis) hybrid host taxa. Trials were established in the field to simulate nematode dispersal both naturally by infected wasps and following commercial inoculation, as well as in the laboratory under controlled conditions. Nematodes showed reduced survival in hybrid pine compared with P. taeda for all tree-associated treatments, but performed equivalently in petri-dish bioassays containing substrate of each taxon. Growth of Amylostereum areolatum, the food source of D. siricidicola was lower on plates containing ground hybrid substrate than on plates containing ground P. taeda. Some physical differences were found between taxa, including differences in bordered pit diameters, tracheid widths, and basic density, but these did not consistently explain reduced performance. More plant secondary compounds (predominantly oleoresins) were present in hybrid taxa than in P. taeda, and in standing trees compared with felled trees. Our results suggested that D. siricidicola may not be as effective in hybrid pine taxa for the biological control of S. noctilio as it is in its current known host taxa, possibly because of reduced growth of its food source, A. areolatum in hybrid pine.