Climate Change May Restrict the Predation Efficiency of Mesocyclops aspericornis (Copepoda: Cyclopidae) on Aedes aegypti (Diptera: Culicidae) Larvae.

Nobuko Tuno,Masahiro Takagi,Tran Vu Phong

doi:10.3390/insects11050307

Nobuko Tuno, Masahiro Takagi + Show 1 more

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https://doi.org/10.3390/insects11050307

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Journal: Insects	Publication Date: May 14, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Kanazawa University, Nagasaki University

Abstract

(1) Dengue is the most spread mosquito-borne viral disease in the world, and vector control is the only available means to suppress its prevalence, since no effective treatment or vaccine has been developed. A biological control program using copepods that feed on mosquito larvae has been practiced in Vietnam and some other countries, but the application of copepods was not always successful. (2) To understand why the utility of copepods varies, we evaluated the predation efficiency of a copepod species (Mesocyclops aspericornis) on a vector species (Aedes aegypti) by laboratory experiments under different temperatures, nutrition and prey-density conditions. (3) We found that copepod predation reduced intraspecific competition among Aedes larvae and then shortened the survivor’s aquatic life and increased their pupal weight. In addition, the predatory efficiency of copepods was reduced at high temperatures. Furthermore, performance of copepod offspring fell when the density of mosquito larvae was high, probably because mosquito larvae had adverse effects on copepod growth through competition for food resources. (4) These results suggest that the increase in mosquitoes will not be suppressed solely by the application of copepods if the density of mosquito larvae is high or ambient temperature is high. We need to consider additional control methods in order to maintain the efficiency of copepods to suppress mosquito increase.

Highlights

Aedes mosquitoes transmit dengue virus that cause dengue fever and dengue haemorrhagic fever [1]
This study aims to understand the effects of environmental conditions on the effectiveness of a copepod species Mesocyclops aspericornis (Daday) as an agent to suppress the increase in Ae. aegypti populations by laboratory experiments in which rearing conditions, i.e., temperature, the amount of foods for mosquitoes and copepods, and the initial density of mosquito larvae, are manipulated
After the findings that cyclopoid copepods substantially feed on mosquito larvae in the field [6,16,24], several studies have proved that copepods are an effective agent to control mosquito populations in northern and central Vietnam [2,3,4,5,7], but the utility of copepods was not always obvious [11]

Summary

Introduction

Aedes mosquitoes transmit dengue virus that cause dengue fever and dengue haemorrhagic fever [1]. A noticeable means for Aedes control is the use of copepod predators. Since the discovery of copepod predation on mosquito larvae, they have been used to control Aedes larvae in temperate, subtropical and tropical regions [2,3,4,5,6,7,8,9]. Copepod application has been proven to suppress mosquito populations in northern and central Vietnam [2,3,4,5,10], but copepod application alone was not effective in southern Vietnam [11]. In a review of several copepod application programs, it is claimed that the effectiveness of copepod application varies according to the differences in community structures and environmental conditions [12]. Still, there have been few experimental studies on this issue [13]

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