Two exotic pests, Argentine stem weevil (ASW) and clover root weevil (CRW) are causing damage estimated at up to $200 M p.a. and $235 M p.a. respectively in dairy and sheep and beef pastures. While CRW is subject to successful biological control management it still causes considerable losses. Lesser pests also contribute to lost production, particularly as they often coexist with more major pests. However, their economic cost to New Zealand is difficult to calculate due to the variable nature of infestations on both temporal and spatial scales. At farm and paddock level, it is abundantly clear that substantial savings could be made if pest management is achieved. It is equally clear that in many instances the tools to do so are limited but if developed would contribute substantially to farm profitability.

Summary 1.One of the ongoing challenges in molecular biology is to develop rapid, accurate and reliable techniques to identify organisms. This contribution evaluates the value of DNA melt peak analysis for the identification of pests and pathogens significant to biosecurity. 2. The method evaluated in this study capitalises on the observation that double-stranded DNA separates into single strands (melts) at a temperature dependant on the nucleotide sequence of the DNA strands. The temperature and shape of melt peaks from polymerase chain reaction (PCR) products using standard primers and amplification protocols were evaluated for species identification, and the advantages of this method over agarose gel electrophoresis exemplified. 3. Three insect (weevil) species were discriminated by the melt profile shape and temperature of their cytochrome oxidase subunit I (COI) PCR product using order-specific universal primers. 4. Three of four arachnid (tick) species were discriminated by the melt profile shape and temperature of their COI and 18S PCR product using order-specific universal primers. 5. Plum pox virus-specific primers amplified only the target virus that was verified by its unique melt temperature rather than by conventional staining of the amplicon on an electrophoretic gel. 6. Melt peak analysis is a useful and robust tool for the rapid detection of PCR products and the identification of organisms. An efficiency study revealed this technique required half the time input, and cost half as much, as PCR followed by AGE.

No abstract

Sitona lepidus had spread throughout the North Island of New Zealand by 2005 and was first detected in the South Island in January 2006 when one individual was found at Harewood Christchurch Intensive sampling during February 2006 recovered only two additional specimens Several specimens were recovered from a separate Christchurch location in August 2006 Localised S lepidus populations were discovered near Richmond Nelson in April 2006 and in Rai Valley in May 2006 A website established in May 2006 to provide information about S lepidus was visited a mean of 135 times per month but it was never used to report possible new South Island infestations A biological control agent Microctonus aethiopoides was released at Richmond and Rai Valley between August 2006 and March 2007 By May 2007 it was parasitising from 4 to 14 of S lepidus adults which indicates it is likely to become permanently established

The population dynamics of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in the Murrumbidgee Valley, Australia, has been characterized using five highly variable microsatellite loci. In the 2001-2002 growing season, there were very high levels of migration into the Murrumbidgee Valley with no detectable genetic structuring, consistent with previous analyses on a national scale. By contrast, there was significant genetic structuring over the 2002-2003 growing season, with three distinct genetic types detected. The first type corresponded to the first two generations and was derived from local individuals emerging from diapause and their progeny. The second genetic type corresponded to generation 3 and resulted from substantial immigration into the region. There was another genetic shift in generation 4, which accounts for the third genetic type of the season. This genetic shift occurred despite low levels of immigration. During the third generation of the 2002-2003 growing season, different population dynamics was characterized for H. armigera on maize, Zea mays L., and cotton Gossipium hirsutum L. Populations on cotton tended to cycle independently with very little immigration from outside the region or from maize within the region. Maize acted as a major sink for immigrants from cotton and from outside the region. If resistance were to develop on cotton under these circumstances, susceptible individuals from maize or from other regions would not dilute this resistance. In addition, resistance is likely to be transferred to maize and be perpetuated until diapause, from where it may reemerge next season. If low levels of immigration were to occur on transgenic cotton, this may undermine the effectiveness of refugia, especially noncotton refugia.