Larvicidal, Ovicidal, Synergistic, and Repellent Activities of Sophora alopecuroides and Its Dominant Constituents Against Aedes albopictus.

Rana Fartab Shoukat,Syed Arif Hussain Rizvi,Shoaib Freed,Xiaoxia Xu,Fengliang Jin,Muhammad Shakeel,Junaid Zafar,Yuxin Zhang

doi:10.3390/insects11040246

Rana Fartab Shoukat, Syed Arif Hussain Rizvi + Show 6 more

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https://doi.org/10.3390/insects11040246

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Abstract

In the current study, to combat insecticide resistance, we explored larvicidal, ovicidal, synergistic, and repellent activities of Sophora alopecuroides extract and its dominant constituents against Aedes albopictus. The results of the toxicity bioassays demonstrated that the extract of S. alopecuroides exerted significant larvicidal activity (16.66–86.66%) against the third-instar larvae of Ae. albopictus at different concentrations (5–50 ug/mL) and low hatchability of eggs (2.32–75%) at 5–50 ug/mL. The constituents of S. alopecuroides showed a synergistic effect when applied as a mixture (LC30 + LC30) against larvae, while no synergistic effect was observed against the eggs of Ae. albopictus. S. alopecuroides extract provided 93.11% repellency in the first 90 min and gradually decreased to 53.14% after 240 min, while the positive control DEET (N,N-diethyl-3-methylbenzamide) showed 94.18% in the first 90 min and 55.33% after 240 min. All of the results exhibited a concentration-dependent effect. To the best of our knowledge, this is the first time that a study has identified a highly effective extract of S. alopecuroides, which could be used as an alternative agent to control larvae and eggs and to repel adults of Ae. albopictus.

Highlights

Mosquito-transmitted diseases, such as malaria, filariasis, dengue fever, chikungunya, zika, and yellow fever, pose a significant public health concern, as a relatively large proportion of the human population is exposed to these infectious diseases, especially in tropical areas [1,2,3]
Lethal (LC50) and sub-lethal (LC30) concentration (95% CL) values for eggs of Ae
The larval mortality observed in our findings demonstrated a concentration-dependent manner, as larval mortality increased with an increase in the concentration of S. alopecuroides extract and its constituents (Sophocarpin and Sophordine), and maximum mortality was achieved at higher concentrations

Summary

Introduction

Mosquito-transmitted diseases, such as malaria, filariasis, dengue fever, chikungunya, zika, and yellow fever, pose a significant public health concern, as a relatively large proportion of the human population is exposed to these infectious diseases, especially in tropical areas [1,2,3]. Known as a secondary vector, Aedes albopictus, in the recent few decades, has emerged as the primary vector in several parts of the world [4]. Though this mosquito is considered the best vector of dengue, it has been reported to play a major role in the transmission of chikungunya and zika virus [3,5]. Large-scale use of synthetic insecticides for the control of mosquitoes has led to the development of resistance in Insects 2020, 11, 246; doi:10.3390/insects11040246 www.mdpi.com/journal/insects

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