%D 2007 %0 MEDLINE %T Changes in levels of juvenile hormone and molting hormone in larvae and adult females of Chilo suppressalis ( Lepidoptera : Pyralidae ) after imidacloprid applications to rice . %J J Econ Entomol %V 100 %P 1188-93 %A Yu YS %A Xue S %A Wu JC %A Wang F %A Yang GQ %M pub17849869 %X Insect hormones regulate growth and development and fecundity of insects . The current study investigated changes in juvenile hormone ( JH ) and molting hormone ( MH ) levels in fourth instars and adult females of Chilo suppressalis ( Walker ) ( Lepidoptera : Pyralidae ) after imidacloprid application to rice , Oryza sativa L The results showed that JH level in fourth instars that developed feeding on Fengyouxiangzhan rice plants sprayed with 15 , 30 , and 60 ppm imidacloprid was significantly higher than that of larvae that developed on control plants , increasing by 5 . 04 , 6 . 39 , and 4 . 89 times , respectively . The relationships between JH level and imidacloprid concentrations showed a significant negative correlation . In contrast , molting hormone ( MH ) level in larvae fed on control plants was significantly higher than that on treated plants . JH : MH values in fourth instars developed from larvae feeding on rice plants treated with 15 , 30 , 60 , 80 , and 100 ppm imidacloprid increased by 49 . 17 , 39 . 43 , 13 . 48 , 15 . 80 , and 0 . 2 times , respectively , compared with control . JH and JH : MH ratio in larvae fed on Wujing 15 plants treated with imidacloprid were significantly lower than those fed on Fengyouxiangzhan under the same treatments . JH level in adult females that developed from larvae feeding on rice plants sprayed with imidacloprid significantly decreased with increase in imidacloprid concentration , but it increased compared with control . JH level in adult females was associated with times of imidacloprid application . JH level in adult females developed from larvae feeding on rice plants after double spray with 30 ppm imidacloprid was significantly higher than control , increasing by 61 . 6 and 116 . 5% , respectively , compared with a single spray and the control . Moreover , hormone levels in the larvae were related to the application method of imidacloprid . JH level in fourth instars after root application and topical application of imidacloprid was significantly lower than in control . Thus , the dynamics of JH and MH in insects after insecticide applications are an extremely interesting problem , because hormones are related to insect growth and development .