The latest official guidance (RESISTANCE MANAGEMENT PLAN FOR INGARD® COTTON 2001-2002 - Transgenic and Insect Management Strategy (TIMS) Committee of the Australian Cotton Growers Research Association - http://www.cotton.pi.csiro.au/Publicat/Pest/IRMS/irms0102.htm) makes it clear that Bt is in some circumstances failing to control the principal target pest it was introduced for. This pest is known as Helicoverpa armigera.

The new guidance states:

"INGARD® cotton should be carefully monitored throughout the season for H. armigera and other pests....

For economic management of H. armigera, larval populations should be controlled with an insecticide if a threshold of two larvae (>3 mm long) per metre continues over two consecutive checks or one medium (>8 mm long) instar larva, or larger, is found on the first check".

It also identifies the following additional concerns:

"Regrowth of INGARD® cotton after picking may allow another generation of H.armigera to be selected for resistance. It is best to avoid this by:

* quickly removing cotton stalks and cultivating the field (preferable option)
* controlling regrowth with defoliants or H. armigera larvae with insecticides".

Previously concerns about the sustainability of the technology have been expressed due either to potential build up of resistant insects or inadequate expression of the Bt transgene in the plants. Perhaps both factors are now playing a role.

Management of these crops is becoming increasingly more difficult. Depending on the region concerned growers are now also required or advised, amongst other things, to:

* locate 'refuges' in dryland situations "in fields with the same cropping history as that of the INGARD field".
* undertake H.armigera pupae destruction after harvest according to strict cultivational guidelines.
* remove volunteer cotton plants as soon as possible from all fields planted with INGARD cotton following conventional cotton; and from all fallowed and conventional fields following INGARD cotton (INGARD plants within conventional cotton fields or conventional plants within INGARD fields both provide additional selection pressure for the development of resistance to the Bt toxin).

All this is easier said than done and therefore places major question marks over the sustainability of the technology. Random audits will be carried out by Monsanto (or their contractors) to monitor compliance with this regime. Growers will receive a rebate if "sprayed record information is supplied as required". Willful non-compliance will result in "no rebate being paid and the denial of access to the technology for a period".