Evaluation on activity and efficacy of Bacillus thuringiensis var. israelensis and S-methoprene against the Asian tiger mosquito, Aedes albopictus (Diptera: Culicidae), in discarded tires
Yijin Chen1,2, Yuting Zheng3, Tianyun Su4,5, Wenbo Hu2,5, Ying Liang2, Xiaobo Liu2,5,6,7,Xiujun Li1, and Qiyong Liu2,5,6,7
1. Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
2. National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, WHO Collaborating Centre for Vector Surveillance and Management, Department of Vector Biology and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
3. Department of Arboviral Diseases Prevention and Control, Yunnan Institute of Parasitic Diseases, Puer, China
4. EcoZone International, Riverside, CA, USA
5. Department of Vector Control, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China
6. Xinjiang Key Laboratory of Vector-borne Infectious Diseases, Urumqi, China
7. Department of Climate Change and Health, School of Public Health, Zhejiang Chinese Medical University, Hangzhou, China.
Abstract
The Asian tiger mosquito, Aedes albopictus Skuse (Diptera: Culicidae), is an important vector of various arboviruses. Effective control of mosquito vectors is essential to prevent the transmission of mosquito-borne iseases; however, sustainable larval control against this species has been otoriously difficult. To enhance effective larval control against Ae. albopictus, a laboratory initial test was conducted to determine the activity of microbial larvicide Bacillus thuringiensis var. israelensis (Bti) and a juvenile hormone analog S-methoprene. The technical grade and formulated product performed similarly in either Bti or S-methoprene. Compared with larvae from a laboratory strain, field-collected mosquitoes showed similar susceptibility to Bti, but significantly lower susceptibility to S-methoprene at IE30 and IE50. In semifield studies to evaluate efficacy of the formulations, as short as a 2-d efficacy was observed for Bti alone at 0.50 ppm, while longer efficacy of up to 3 and 4 wk was achieved by the S-methoprene treatments alone at 1 and 5 ppb, respectively, due to different modes of action and formulation technologies. The combination of Bti at 0.25 ppm and S-methoprene at 2.5 ppb exhibited an extended effect for up to 4 wk as in S-methoprene alone at 5 ppb. The efficacy of both insecticides was impacted by sunlight and dilution. Larvae from field collections were less susceptible to S-methoprene than those of laboratory colony in the semifield evaluation in discarded tires. The practicality of Bti and S-methoprene products for controlling Ae. albopictus in discarded tires was discussed in relation to the findings in current studies.
Keywords microbial larvicide, juvenile hormone analog, Aedes albopictus, discarded tires, semifield evaluation
For additional information , please refer to the original source https://doi.org/10.1093/jme/tjaf057