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.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 100 • No. 4