Abstract1 The potential risk of the establishment of the Asian strain of the gypsy moth (AGM) (Lymantria dispar) in New Zealand and Australia (Australasia) was assessed from a study of the insect's host range and potential distribution. In New Zealand, viable eggs of AGM have been continuously intercepted on cargo from Asia, and therefore there is a high probability of accidental introductions of AGM to Australasia.2 We predicted potential distribution ranges of AGM based on climatic conditions. Asian gypsy moth is predicted to be able to persist in N and SE New Zealand and SE and SW Australia.3 Using three populations of AGM and 59 species (seven families) of plant (55 from Australasia and four from elsewhere), we also conducted laboratory trials to examine the ability of AGM larvae to complete development on native plants from Australasia. Asian gypsy moth was able to complete development on 26 out of the 55 native species tested. Furthermore, larval performance on at least five species of Australian native plant was as good as on AGM's preferred host species (Quercus pubescens and Q. robur).4 Larval performance of AGM was poor on all but one species of New Zealand native tree species (Nothofagus solandri), and therefore the risk of establishment in the indigenous forests of New Zealand is considered to be low.5 Given the suitability of some Australian plants and the climatic suitability for the establishment of AGM, this insect should be treated as a serious quarantine threat and managed accordingly, particularly in Australia.
Paropsis charybdis, the most serious pest of Eucalyptus in New Zealand, was controlled with the introduced Australian egg parasitoid Enoggera nassaui in the late 1980s. Using frass traps to monitor P. charybdis populations, we report that pest outbreaks still occur, resulting in heavy defoliation of susceptible Eucalyptus species. The results suggest that the presence of large larval populations and commensurate defoliation result from poor spring parasitism by the parasitoid. A second wave of P. charybdis oviposition is effectively attacked, preventing late season defoliation by larvae. A climatic mismatch of E. nassaui is suspected to be the cause of this poor performance.
Wildings from exotic tree plantations are a major threat to New Zealand's native vegetation and landscapes. The insects associated with the reproductive structures of the most significant invasive tree, Pinus contorta, are reviewed with regard to their suitability for biological control. Based on host species and structure specificity and their impact on seed production, Conophthorus ponderosae (Scolytidae), Eucosma rescissoriana (Tortricidae) and Pissodes validirostris (Curculionidae) are the most promising biocontrol candidates among the 16 North American or Eurasian insect species recorded as feeding on P. contorta cones. Further studies are needed to assess whether these insects could significantly reduce the rate of spread of P. contorta and would not pose a threat to any native plants or plantation forestry trees.
Between January 2002 and May 2004 a series of aerially applied sprays of Btk (Bacillus thuringiensis var kurstaski) were made to areas of Auckland and Hamilton New Zealand The purpose of the sprays was to eradicate the painted apple moth (PAM; Teia anartoides) from Auckland and the Asian gypsy moth (AGM; Lymantria dispar) from Hamilton In both operations bioassays were used to test the effectiveness and consistency of spray applications Bioassays were undertaken by placing foliage samples (Acacia mearnsii) at a selection of locations in the spray zone next to cards on which spray deposition was measured After spraying PAM larvae were placed on each plant and mortality recorded Results indicated that there was a strong relationship between droplet density on cards and PAM mortality on plants Once this relationship was determined further bioassays were of limited additional value to simply measuring deposition on cards
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