The Asiatic rice borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae), is an important rice, Oryza sativa L., pest in China and difficult to control with conventional pest management. To develop and optimize integrated pest management strategies, efficient and economic artificial diet and rearing protocols are desirable. A new artificial diet based on soybean, Glycine max (L.) Merr., powder and fresh water bamboo, Zizania caduciflora (Turcz.) Hand.-Mazz, was formulated and rearing technique was developed. Fitness parameters including larval development, immature survival, pupal weight, pupation, adult emergence, egg hatchability, and oviposition were measured to evaluate the performance of C. suppressalis fed on the diet over 15 successive generations. C. suppressalis reared on the artificial diet showed better performance with shorter developmental stage, similar larval survival rate and fecundity, and heavier pupae compared with that fed on rice plants and fresh water bamboo. A positive correlation was observed between number of eggs laid per female and number of generations reared on the diet. Larval development time tended to be shortened with successive rearing on the artificial diet. These results indicated that C. suppressalis adapted well to the artificial diet and successive rearing conditions. The diet could serve as a viable alternative to natural host plants for consecutive rearing of the insect. In addition, the diet is inexpensive (US$1.5/1,000 g) and easy to make. The better preserve ability of the diet required only one diet replacement during the rearing process. The successful development of the diet and rearing technique provides a very useful tool for refining stem borer pest management techniques.

Two transgenic rice lines (T2A-1 and T1C-19b) expressing cry2A and cry1C genes, respectively, were developed in China, targeting lepidopteran pests including Chilo suppressalis (Walker) (Lepidoptera: Crambidae). The seasonal expression of Cry proteins in different tissues of the rice lines and their resistance to C. suppressalis were assessed in comparison to a Bt rice line expressing a cry1Ab/Ac fusion gene, Huahui 1, which has been granted a biosafety certificate. In general, levels of Cry proteins were T2A-1 > Huahui 1 > T1C-19b among rice lines, and leaf > stem > root among rice tissues. The expression patterns of Cry protein in the rice line plants were similar: higher level at early stages than at later stages with an exception that high Cry1C level in T1C-19b stems at the maturing stage. The bioassay results revealed that the three transgenic rice lines exhibited significantly high resistance against C. suppressalis larvae throughout the rice growing season. According to Cry protein levels in rice tissues, the raw and corrected mortalities of C. suppressalis caused by each Bt rice line were the highest in the seedling and declined through the jointing stage with an exception for T1C-19b providing an excellent performance at the maturing stage. By comparison, T1C-19b exhibited more stable and greater resistance to C. suppressalis larvae than T2A-1, being close to Huahui 1. The results suggest cry1C is an ideal Bt gene for plant transformation for lepidopteran pest control, and T1C-19b is a promising Bt rice line for commercial use for tolerating lepidopteran rice pests.

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