Genetically modified Bt cotton, expressing the Cry1Ac protein for specific insecticidal activity against economically significant lepidopteran pests, has been available commercially in Australia since 1996. This technology has been improved and superseded by the addition of a second gene, allowing new varieties to express both the Cry1Ac the Cry2Ab proteins. Bt cotton offers several advantages to the grower, mainly through reduced insecticide spray requirements. The environmental benefits of reduced insecticide usage are assessed in this paper using the environmental impact quotient (EIQ). The assessment included consideration of the impact of the expressed transgenic proteins Cry1Ac and Cry2Ab. EIQ values of the Cry1Ac and Cry2Ab proteins were calculated at 9.9 and 7.9, respectively. Bt protein expression, plant biomass, insecticide application records, constituent of active ingredient, and insecticide EIQ values were used to produce an environmental impact (EI) value for insecticide use (kg a.i./ha) for conventional non-GM and single- and 2-gene Bt cotton for the 1997–98 to 2003–04 seasons. Inclusion of the Cry proteins in the assessment increased the EI values for Bt cotton by only 2%. The average insecticide EI value, for 2002–03 and 2003–04 seasons, for conventional cotton was 135 kg a.i./ha, whereas for the 2-gene Bt variety it was only 28 kg a.i./ha. Results of the EI evaluation indicate that, due to changes in insecticidal choice and reduction in usage, there was a reduction of >64% in EI from growing Bt cotton compared with conventional non-GM cotton in Australia.

The developmental time of the green mirid Creontiades dilutus (St81) reared on green bean was examined 1°C. Using thermal summation and a threshold in relation to 5 temperatures ranging from 19 to 31 temperature of 12.3"C, 280 day-degrees was estimated for development from egg to adult. IntroductionThe green mirid, Creontiudes dilutus (Stll) (junior synonym: Megucoelurn modesturn Distant) is known to attack several agricultural crops in Australia (Woodward et ul. 1970) including grapes, potatoes, lucerne, and cotton. On cotton, adults and nymphs feed on the growing points of young plants, causing the destruction of vegetative buds (Adams and Pyke pers. comm.) and the abscission of flower buds (Bishop 1980). A sound understanding of the biology of C. dilutus is necessary for development of control strategies for this pest which will be compatible with current control strategies for the principal pests of cotton. However, C. dilutus is not always available from the field in sufficient numbers for study, and there are no published reports of it being reared in the laboratory. North American mirids have been reared on a variety of substrates, including the green bean, Phuseolus vulguris L. (e.g. Butler and Wardecker 1971). The advantages of using green bean are that it is cheap, easy to handle and readily available throughout most of the year. This paper describes the relationship between temperature and development of C. dilutus reared on green bean.

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