Insect bioassay techniques for screening Bt transgenic cotton plants

Development of efficient insect bioassays is imperative for rapid screening of Bt cotton for insect resistance. The transgenic cotton plants are assessed for insect resistance using part of the plant only ie leaf disc or detached leaf assays. This is the non-destructive method most commonly adopted for screening of transformed plants for insect resistance in early generations. Whereas bioassay using whole plants is the destructive method mainly used for screening further progeny plants since it reflects field condition. However these bioassays are time consuming, often laborious and require a lot of space which make them a hard choice for testing the efficacy of Cry toxins against target pests in greenhouse and large scale field studies. Screening of transgenic cotton plants using efficient bioassay techniques leads to the design of effective tools for controlling insect pests.