Feeding behavior of Spodoptera exigua larvae on insect-resistant transgenic cotton and non-transgenic cotton.

Feeding choice of Spodoptera exigua larvae between conventional and transgenic cotton,effects of learning on their feeding choice,and pupal weight on transgenic and conventional cotton were investigated.Results showed that 3rd and 5th instars of S.exigua reared with artificial diet did not exhibit avoiding response to transgenic cotton leaves,except that more 5th instars chose the conventional variety Shiyuan321 at 24 h,and even more larvae chose to feed on transgenic leaves.The 3rd instars raised with 33 or 33B cotton leaves did not avoid the transgenic leaves of 33B in choice test between 33 and 33B,and similar result was obtained in choice test with Shiyuan321 and SGK321 cotton leaves.Moreover,in any of above treatments,there was no significant difference in pupal weight between those obtained on the conventional cotton leaves and those on the transgenic cotton leaves.Our study indicated S.exigua larvae did not exhibit behavioral resistance to transgenic cotton 33B and SGK321.Hence,much more attention should be paid to the control of S.exigua in the transgenic cotton field.